text: /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
   * Copyright by The HDF Group.                                               *
   * Copyright by the Board of Trustees of the University of Illinois.         *
   * All rights reserved.                                                      *
   *                                                                           *
   * This file is part of HDF5.  The full HDF5 copyright notice, including     *
   * terms governing use, modification, and redistribution, is contained in    *
   * the files COPYING and Copyright.html.  COPYING can be found at the root   *
   * of the source code distribution tree; Copyright.html can be found at the  *
   * root level of an installed copy of the electronic HDF5 document set and   *
   * is linked from the top-level documents page.  It can also be found at     *
   * http://hdfgroup.org/HDF5/doc/Copyright.html.  If you do not have          *
   * access to either file, you may request a copy from help@hdfgroup.org.     *
   * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  
  /*
   * Programmer:  Quincey Koziol <koziol@ncsa.uiuc.edu>
   *              Thursday, June 18, 1998
   *
   * Purpose:	Hyperslab selection data space I/O functions.
   */
  
  #define H5S_PACKAGE		/*suppress error about including H5Spkg	  */
  
  
  #include "H5private.h"		/* Generic Functions			*/
  #include "H5Eprivate.h"		/* Error handling			*/
  #include "H5FLprivate.h"	/* Free Lists				*/
  #include "H5Iprivate.h"		/* ID Functions				*/
  #include "H5Spkg.h"		/* Dataspace functions			*/
  #include "H5VMprivate.h"         /* Vector functions			*/
  
  /* Local datatypes */
  
  /* Static function prototypes */
  static herr_t H5S_hyper_free_span_info(H5S_hyper_span_info_t *span_info);
  static herr_t H5S_hyper_free_span(H5S_hyper_span_t *span);
  static H5S_hyper_span_info_t *H5S_hyper_copy_span(H5S_hyper_span_info_t *spans);
  static void H5S_hyper_span_scratch(H5S_hyper_span_info_t *spans, void *scr_value);
  static herr_t H5S_hyper_span_precompute(H5S_hyper_span_info_t *spans, size_t elmt_size);
  static herr_t H5S_generate_hyperslab(H5S_t *space, H5S_seloper_t op,
      const hsize_t start[], const hsize_t stride[], const hsize_t count[], const hsize_t block[]);
  static herr_t H5S_hyper_generate_spans(H5S_t *space);
  /* Needed for use in hyperslab code (H5Shyper.c) */
  #ifdef NEW_HYPERSLAB_API
  static herr_t H5S_select_select (H5S_t *space1, H5S_seloper_t op, H5S_t *space2);
  #endif /*NEW_HYPERSLAB_API*/
  
  /* Selection callbacks */
  static herr_t H5S_hyper_copy(H5S_t *dst, const H5S_t *src, hbool_t share_selection);
  static herr_t H5S_hyper_get_seq_list(const H5S_t *space, unsigned flags,
      H5S_sel_iter_t *iter, size_t maxseq, size_t maxbytes,
      size_t *nseq, size_t *nbytes, hsize_t *off, size_t *len);
  static herr_t H5S_hyper_release(H5S_t *space);
  static htri_t H5S_hyper_is_valid(const H5S_t *space);
  static hssize_t H5S_hyper_serial_size(const H5S_t *space);
  static herr_t H5S_hyper_serialize(const H5S_t *space, uint8_t *buf);
  static herr_t H5S_hyper_deserialize(H5S_t *space, const uint8_t *buf);
  static herr_t H5S_hyper_bounds(const H5S_t *space, hsize_t *start, hsize_t *end);
  static herr_t H5S_hyper_offset(const H5S_t *space, hsize_t *offset);
  static htri_t H5S_hyper_is_contiguous(const H5S_t *space);
  static htri_t H5S_hyper_is_single(const H5S_t *space);
  static htri_t H5S_hyper_is_regular(const H5S_t *space);
  static herr_t H5S_hyper_adjust_u(H5S_t *space, const hsize_t *offset);
  static herr_t H5S_hyper_project_scalar(const H5S_t *space, hsize_t *offset);
  static herr_t H5S_hyper_project_simple(const H5S_t *space, H5S_t *new_space, hsize_t *offset);
  static herr_t H5S_hyper_iter_init(H5S_sel_iter_t *iter, const H5S_t *space);
  
  /* Selection iteration callbacks */
  static herr_t H5S_hyper_iter_coords(const H5S_sel_iter_t *iter, hsize_t *coords);
  static herr_t H5S_hyper_iter_block(const H5S_sel_iter_t *iter, hsize_t *start, hsize_t *end);
  static hsize_t H5S_hyper_iter_nelmts(const H5S_sel_iter_t *iter);
  static htri_t H5S_hyper_iter_has_next_block(const H5S_sel_iter_t *sel_iter);
  static herr_t H5S_hyper_iter_next(H5S_sel_iter_t *sel_iter, size_t nelem);
  static herr_t H5S_hyper_iter_next_block(H5S_sel_iter_t *sel_iter);
  static herr_t H5S_hyper_iter_release(H5S_sel_iter_t *sel_iter);
  
  /* Static function for optimizing hyperslab */
  static hbool_t H5S_hyper_rebuild_helper(const H5S_hyper_span_t *span,
      H5S_hyper_dim_t span_slab_info[], unsigned rank);
  static htri_t H5S_hyper_rebuild(H5S_t *space);
  
  /* Selection properties for hyperslab selections */
  const H5S_select_class_t H5S_sel_hyper[1] = {{
      H5S_SEL_HYPERSLABS,
  
      /* Methods on selection */
      H5S_hyper_copy,
      H5S_hyper_get_seq_list,
      H5S_hyper_release,
      H5S_hyper_is_valid,
      H5S_hyper_serial_size,
      H5S_hyper_serialize,
      H5S_hyper_deserialize,
      H5S_hyper_bounds,
      H5S_hyper_offset,
      H5S_hyper_is_contiguous,
      H5S_hyper_is_single,
      H5S_hyper_is_regular,
      H5S_hyper_adjust_u,
      H5S_hyper_project_scalar,
      H5S_hyper_project_simple,
      H5S_hyper_iter_init,
  }};
  
  /* Iteration properties for hyperslab selections */
  static const H5S_sel_iter_class_t H5S_sel_iter_hyper[1] = {{
      H5S_SEL_HYPERSLABS,
  
      /* Methods on selection iterator */
      H5S_hyper_iter_coords,
      H5S_hyper_iter_block,
      H5S_hyper_iter_nelmts,
      H5S_hyper_iter_has_next_block,
      H5S_hyper_iter_next,
      H5S_hyper_iter_next_block,
      H5S_hyper_iter_release,
  }};
  
  /* Static variables */
  
  /* Array for default stride, block, etc. */
  static const hsize_t _ones[H5O_LAYOUT_NDIMS]={
      1,1,1,1, 1,1,1,1,
      1,1,1,1, 1,1,1,1,
      1,1,1,1, 1,1,1,1,
      1,1,1,1, 1,1,1,1,1};
  
  /* Declare a free list to manage the H5S_hyper_sel_t struct */
  H5FL_DEFINE_STATIC(H5S_hyper_sel_t);
  
  /* Declare a free list to manage the H5S_hyper_span_t struct */
  H5FL_DEFINE_STATIC(H5S_hyper_span_t);
  
  /* Declare a free list to manage the H5S_hyper_span_info_t struct */
  H5FL_DEFINE_STATIC(H5S_hyper_span_info_t);
  
  /* #define H5S_HYPER_DEBUG */
  #ifdef H5S_HYPER_DEBUG
  static herr_t
  H5S_hyper_print_spans_helper(FILE *f, struct H5S_hyper_span_t *span,unsigned depth)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      while(span) {
          HDfprintf(f,"%s: depth=%u, span=%p, (%d, %d), nelem=%u, pstride=%u\n",FUNC,depth,span,(int)span->low,(int)span->high,(unsigned)span->nelem,(unsigned)span->pstride);
          if(span->down && span->down->head) {
              HDfprintf(f,"%s: spans=%p, count=%u, scratch=%p, head=%p\n",FUNC,span->down,span->down->count,span->down->scratch,span->down->head);
              H5S_hyper_print_spans_helper(f,span->down->head,depth+1);
          } /* end if */
          span=span->next;
      } /* end while */
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }
  
  herr_t
  H5S_hyper_print_spans(FILE *f, const struct H5S_hyper_span_info_t *span_lst)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      if(span_lst!=NULL) {
          HDfprintf(f,"%s: spans=%p, count=%u, scratch=%p, head=%p\n",FUNC,span_lst,span_lst->count,span_lst->scratch,span_lst->head);
          H5S_hyper_print_spans_helper(f,span_lst->head,0);
      } /* end if */
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }
  
  herr_t
  H5S_space_print_spans(FILE *f, const H5S_t *space)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      H5S_hyper_print_spans(f,space->select.sel_info.hslab->span_lst);
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }
  
  static herr_t
  H5S_hyper_print_diminfo_helper(FILE *f, const char *field, unsigned ndims, const H5S_hyper_dim_t *dinfo)
  {
      unsigned u;                 /* Local index variable */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      if(dinfo!=NULL) {
          HDfprintf(f,"%s: %s: start=[",FUNC,field);
          for(u=0; u<ndims; u++)
              HDfprintf(f,"%Hd%s",dinfo[u].start, (u<(ndims-1) ? ", " : "]\n"));
          HDfprintf(f,"%s: %s: stride=[",FUNC,field);
          for(u=0; u<ndims; u++)
              HDfprintf(f,"%Hu%s",dinfo[u].stride, (u<(ndims-1) ? ", " : "]\n"));
          HDfprintf(f,"%s: %s: count=[",FUNC,field);
          for(u=0; u<ndims; u++)
              HDfprintf(f,"%Hu%s",dinfo[u].count, (u<(ndims-1) ? ", " : "]\n"));
          HDfprintf(f,"%s: %s: block=[",FUNC,field);
          for(u=0; u<ndims; u++)
              HDfprintf(f,"%Hu%s",dinfo[u].block, (u<(ndims-1) ? ", " : "]\n"));
      } /* end if */
      else
          HDfprintf(f,"%s: %s==NULL\n",FUNC,field);
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }
  
  herr_t
  H5S_hyper_print_diminfo(FILE *f, const H5S_t *space)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      H5S_hyper_print_diminfo_helper(f,"opt_diminfo",space->extent.rank,space->select.sel_info.hslab->opt_diminfo);
      H5S_hyper_print_diminfo_helper(f,"app_diminfo",space->extent.rank,space->select.sel_info.hslab->app_diminfo);
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }
  #endif /* H5S_HYPER_DEBUG */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_hyper_iter_init
   *
   * Purpose:	Initializes iteration information for hyperslab span tree selection.
   *
   * Return:	non-negative on success, negative on failure.
   *
   * Programmer:	Quincey Koziol
   *              Saturday, February 24, 2001
   *
   * Notes:       If the 'elmt_size' parameter is set to zero, the regular
   *              hyperslab selection iterator will not be 'flattened'.  This
   *              is used by the H5S_select_shape_same() code to avoid changing
   *              the rank and appearance of the selection.
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_hyper_iter_init(H5S_sel_iter_t *iter, const H5S_t *space)
  {
      const H5S_hyper_dim_t *tdiminfo;    /* Temporary pointer to diminfo information */
      H5S_hyper_span_info_t *spans;   /* Pointer to hyperslab span info node */
      unsigned rank;                  /* Dataspace's dimension rank */
      unsigned u;                     /* Index variable */
      int i;                          /* Index variable */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(space && H5S_SEL_HYPERSLABS == H5S_GET_SELECT_TYPE(space));
      HDassert(iter);
  
      /* Initialize the number of points to iterate over */
      iter->elmt_left = space->select.num_elem;
      iter->u.hyp.iter_rank = 0;
  
      /* Get the rank of the dataspace */
      rank = space->extent.rank;
  
      /* Set the temporary pointer to the dimension information */
      tdiminfo = space->select.sel_info.hslab->opt_diminfo;
  
      /* Check for the special case of just one H5Sselect_hyperslab call made */
      if(space->select.sel_info.hslab->diminfo_valid) {
  /* Initialize the information needed for regular hyperslab I/O */
          const hsize_t *mem_size;    /* Temporary pointer to dataspace extent's dimension sizes */
          hsize_t acc;                /* Accumulator for "flattened" dimension's sizes */
          unsigned cont_dim = 0;      /* # of contiguous dimensions */
  
          /* Set the temporary pointer to the dataspace extent's dimension sizes */
          mem_size = space->extent.size;
  
          /*
           * For a regular hyperslab to be contiguous up to some dimension, it
           * must have only one block (i.e. count==1 in all dimensions up to that
           * dimension) and the block size must be the same as the dataspace's
           * extent in that dimension and all dimensions up to that dimension.
           */
  
          /* Don't flatten adjacent elements into contiguous block if the
           * element size is 0.  This is for the H5S_select_shape_same() code.
           */
          if(iter->elmt_size > 0) {
              /* Check for any "contiguous" blocks that can be flattened */
              for(u = (rank - 1); u > 0; u--) {
                  if(tdiminfo[u].count == 1 && tdiminfo[u].block == mem_size[u]) {
                      cont_dim++;
                      iter->u.hyp.flattened[u] = TRUE;
                  } /* end if */
                  else
                      iter->u.hyp.flattened[u] = FALSE;
              } /* end for */
              iter->u.hyp.flattened[0] = FALSE;
          } /* end if */
  
          /* Check if the regular selection can be "flattened" */
          if(cont_dim > 0) {
              unsigned last_dim_flattened = 1;    /* Flag to indicate that the last dimension was flattened */
              unsigned flat_rank = rank-cont_dim; /* Number of dimensions after flattening */
              unsigned curr_dim;                  /* Current dimension */
  
              /* Set the iterator's rank to the contiguous dimensions */
              iter->u.hyp.iter_rank = flat_rank;
  
              /* "Flatten" dataspace extent and selection information */
              curr_dim = flat_rank - 1;
              for(i = (int)rank - 1, acc = 1; i >= 0; i--) {
                  if(tdiminfo[i].block == mem_size[i] && i > 0) {
                      /* "Flatten" this dimension */
                      HDassert(tdiminfo[i].start == 0);
                      acc *= mem_size[i];
  
                      /* Indicate that the dimension was flattened */
                      last_dim_flattened = 1;
                  } /* end if */
                  else {
                      if(last_dim_flattened) {
                          /* First dimension after flattened dimensions */
                          iter->u.hyp.diminfo[curr_dim].start = tdiminfo[i].start * acc;
  
                          /* Special case for single block regular selections */
                          if(tdiminfo[i].count == 1)
                              iter->u.hyp.diminfo[curr_dim].stride = 1;
                          else
                              iter->u.hyp.diminfo[curr_dim].stride = tdiminfo[i].stride * acc;
                          iter->u.hyp.diminfo[curr_dim].count = tdiminfo[i].count;
                          iter->u.hyp.diminfo[curr_dim].block = tdiminfo[i].block * acc;
                          iter->u.hyp.size[curr_dim] = mem_size[i] * acc;
                          iter->u.hyp.sel_off[curr_dim] = space->select.offset[i] * (hssize_t)acc;
  
                          /* Reset the "last dim flattened" flag to avoid flattened any further dimensions */
                          last_dim_flattened = 0;
  
                          /* Reset the "accumulator" for possible further dimension flattening */
                          acc = 1;
                      } /* end if */
                      else {
                          /* All other dimensions */
                          iter->u.hyp.diminfo[curr_dim].start = tdiminfo[i].start;
                          iter->u.hyp.diminfo[curr_dim].stride = tdiminfo[i].stride;
                          iter->u.hyp.diminfo[curr_dim].count = tdiminfo[i].count;
                          iter->u.hyp.diminfo[curr_dim].block = tdiminfo[i].block;
                          iter->u.hyp.size[curr_dim] = mem_size[i];
                          iter->u.hyp.sel_off[curr_dim] = space->select.offset[i];
                      } /* end else */
  
                      /* Decrement "current" flattened dimension */
                      curr_dim--;
                  } /* end if */
              } /* end for */
  
              /* Initialize "flattened" iterator offset to initial location and dataspace extent and selection information to correct values */
              for(u = 0; u < flat_rank; u++)
                  iter->u.hyp.off[u] = iter->u.hyp.diminfo[u].start;
          } /* end if */
          else {
              /* Initialize position to initial location */
              /* Also make local copy of the regular selection information */
              for(u = 0; u < rank; u++) {
                  /* Regular selection information */
                  iter->u.hyp.diminfo[u].start = tdiminfo[u].start;
                  iter->u.hyp.diminfo[u].stride = tdiminfo[u].stride;
                  iter->u.hyp.diminfo[u].count = tdiminfo[u].count;
                  iter->u.hyp.diminfo[u].block = tdiminfo[u].block;
  
                  /* Position information */
                  iter->u.hyp.off[u] = tdiminfo[u].start;
              } /* end if */
          } /* end else */
  
          /* Flag the diminfo information as valid in the iterator */
          iter->u.hyp.diminfo_valid = TRUE;
  
          /* Initialize irregular region information also (for release) */
          iter->u.hyp.spans = NULL;
      } /* end if */
      else {
  /* Initialize the information needed for non-regular hyperslab I/O */
          HDassert(space->select.sel_info.hslab->span_lst);
          /* Make a copy of the span tree to iterate over */
          iter->u.hyp.spans = H5S_hyper_copy_span(space->select.sel_info.hslab->span_lst);
  
          /* Set the nelem & pstride values according to the element size */
          H5S_hyper_span_precompute(iter->u.hyp.spans,iter->elmt_size);
  
          /* Initialize the starting span_info's and spans */
          spans = iter->u.hyp.spans;
          for(u = 0; u < rank; u++) {
              /* Set the pointers to the initial span in each dimension */
              HDassert(spans);
              HDassert(spans->head);
  
              /* Set the pointer to the first span in the list for this node */
              iter->u.hyp.span[u] = spans->head;
  
              /* Set the initial offset to low bound of span */
              iter->u.hyp.off[u] = iter->u.hyp.span[u]->low;
  
              /* Get the pointer to the next level down */
              spans = spans->head->down;
          } /* end for */
  
          /* Flag the diminfo information as not valid in the iterator */
          iter->u.hyp.diminfo_valid = FALSE;
      } /* end else */
  
      /* Initialize type of selection iterator */
      iter->type = H5S_sel_iter_hyper;
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_iter_init() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_hyper_iter_coords
   *
   * Purpose:	Retrieve the current coordinates of iterator for current
   *              selection
   *
   * Return:	non-negative on success, negative on failure
   *
   * Programmer:	Quincey Koziol
   *              Tuesday, April 22, 2003
   *
   * Modifications:
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_hyper_iter_coords (const H5S_sel_iter_t *iter, hsize_t *coords)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(iter);
      HDassert(coords);
  
      /* Copy the offset of the current point */
  
      /* Check for a single "regular" hyperslab */
      if(iter->u.hyp.diminfo_valid) {
          /* Check if this is a "flattened" regular hyperslab selection */
          if(iter->u.hyp.iter_rank != 0 && iter->u.hyp.iter_rank < iter->rank) {
              int u, v;           /* Dimension indices */
  
              /* Set the starting rank of both the "natural" & "flattened" dimensions */
              u = (int)iter->rank - 1;
              v = (int)iter->u.hyp.iter_rank - 1;
  
              /* Construct the "natural" dimensions from a set of flattened coordinates */
              while(u >= 0) {
                  if(iter->u.hyp.flattened[u]) {
                      int begin = u;      /* The rank of the first flattened dimension */
  
                      /* Walk up through as many flattened dimensions as possible */
                      do {
                          u--;
                      } while(u >= 0 && iter->u.hyp.flattened[u]);
  
                      /* Compensate for possibly overshooting dim 0 */
                      if(u < 0)
                          u = 0;
  
                      /* Sanity check */
                      HDassert(v >= 0);
  
                      /* Compute the coords for the flattened dimensions */
                      H5VM_array_calc(iter->u.hyp.off[v], (unsigned)((begin - u) + 1), &(iter->dims[u]), &(coords[u]));
  
                      /* Continue to faster dimension in both indices */
                      u--;
                      v--;
                  } /* end if */
                  else {
                      /* Walk up through as many non-flattened dimensions as possible */
                      while(u >= 0 && !iter->u.hyp.flattened[u]) {
                          /* Sanity check */
                          HDassert(v >= 0);
  
                          /* Copy the coordinate */
                          coords[u] = iter->u.hyp.off[v];
  
                          /* Continue to faster dimension in both indices */
                          u--;
                          v--;
                      } /* end while */
                  } /* end else */
              } /* end while */
              HDassert(v < 0);
          } /* end if */
          else
              HDmemcpy(coords, iter->u.hyp.off, sizeof(hsize_t) * iter->rank);
      } /* end if */
      else
          HDmemcpy(coords, iter->u.hyp.off, sizeof(hsize_t) * iter->rank);
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_iter_coords() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_hyper_iter_block
   *
   * Purpose:	Retrieve the current block of iterator for current
   *              selection
   *
   * Return:	non-negative on success, negative on failure
   *
   * Programmer:	Quincey Koziol
   *              Monday, June 2, 2003
   *
   * Notes:       This routine assumes that the iterator is always located at
   *              the beginning of a block.
   *
   * Modifications:
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_hyper_iter_block (const H5S_sel_iter_t *iter, hsize_t *start, hsize_t *end)
  {
      unsigned u;                 /* Local index variable */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(iter);
      HDassert(start);
      HDassert(end);
  
      /* Copy the offset of the current point */
  
      /* Check for a single "regular" hyperslab */
      if(iter->u.hyp.diminfo_valid) {
          /* Compute the end of the block */
          for(u=0; u<iter->rank; u++) {
              start[u]=iter->u.hyp.off[u];
              end[u]=(start[u]+iter->u.hyp.diminfo[u].block)-1;
          } /* end for */
      } /* end if */
      else {
          /* Copy the start of the block */
          for(u=0; u<iter->rank; u++)
              start[u]=iter->u.hyp.span[u]->low;
  
          /* Copy the end of the block */
          for(u=0; u<iter->rank; u++)
              end[u]=iter->u.hyp.span[u]->high;
      } /* end else */
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_iter_block() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_hyper_iter_nelmts
   *
   * Purpose:	Return number of elements left to process in iterator
   *
   * Return:	non-negative number of elements on success, zero on failure
   *
   * Programmer:	Quincey Koziol
   *              Tuesday, June 16, 1998
   *
   * Modifications:
   *
   *-------------------------------------------------------------------------
   */
  static hsize_t
  H5S_hyper_iter_nelmts (const H5S_sel_iter_t *iter)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(iter);
  
      FUNC_LEAVE_NOAPI(iter->elmt_left)
  }   /* H5S_hyper_iter_nelmts() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_iter_has_next_block
   PURPOSE
      Check if there is another block left in the current iterator
   USAGE
      htri_t H5S_hyper_iter_has_next_block(iter)
          const H5S_sel_iter_t *iter;       IN: Pointer to selection iterator
   RETURNS
      Non-negative (TRUE/FALSE) on success/Negative on failure
   DESCRIPTION
      Check if there is another block available in the selection iterator.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static htri_t
  H5S_hyper_iter_has_next_block(const H5S_sel_iter_t *iter)
  {
      unsigned u;                 /* Local index variable */
      htri_t ret_value = FALSE;   /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(iter);
  
      /* Check for a single "regular" hyperslab */
      if(iter->u.hyp.diminfo_valid) {
          const H5S_hyper_dim_t *tdiminfo;    /* Temporary pointer to diminfo information */
          const hsize_t *toff;               /* Temporary offset in selection */
  
          /* Check if the offset of the iterator is at the last location in all dimensions */
          tdiminfo = iter->u.hyp.diminfo;
          toff = iter->u.hyp.off;
          for(u = 0; u < iter->rank; u++) {
              /* If there is only one block, continue */
              if(tdiminfo[u].count == 1)
                  continue;
              if(toff[u] != (tdiminfo[u].start + ((tdiminfo[u].count - 1) * tdiminfo[u].stride)))
                  HGOTO_DONE(TRUE);
          } /* end for */
      } /* end if */
      else {
          /* Check for any levels of the tree with more sequences in them */
          for(u = 0; u < iter->rank; u++)
              if(iter->u.hyp.span[u]->next != NULL)
                  HGOTO_DONE(TRUE);
      } /* end else */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_iter_has_next_block() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_hyper_iter_next
   *
   * Purpose:	Moves a hyperslab iterator to the beginning of the next sequence
   *      of elements to read.  Handles walking off the end in all dimensions.
   *
   * Return:	Success:	non-negative
   *		Failure:	negative
   *
   * Programmer:	Quincey Koziol
   *              Friday, September 8, 2000
   *
   * Modifications:
   *      Modified for both general and optimized hyperslab I/O
   *      Quincey Koziol, April 17, 2003
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_hyper_iter_next(H5S_sel_iter_t *iter, size_t nelem)
  {
      unsigned ndims;     /* Number of dimensions of dataset */
      int fast_dim;       /* Rank of the fastest changing dimension for the dataspace */
      unsigned i;         /* Counters */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check for the special case of just one H5Sselect_hyperslab call made */
      /* (i.e. a regular hyperslab selection */
      if(iter->u.hyp.diminfo_valid) {
          const H5S_hyper_dim_t *tdiminfo;    /* Temporary pointer to diminfo information */
          hsize_t iter_offset[H5O_LAYOUT_NDIMS];
          hsize_t iter_count[H5O_LAYOUT_NDIMS];
          int temp_dim;  /* Temporary rank holder */
  
          /* Check if this is a "flattened" regular hyperslab selection */
          if(iter->u.hyp.iter_rank!=0 && iter->u.hyp.iter_rank<iter->rank) {
              /* Set the aliases for the dimension rank */
              ndims=iter->u.hyp.iter_rank;
          } /* end if */
          else {
              /* Set the aliases for the dimension rank */
              ndims=iter->rank;
          } /* end else */
  
          /* Set the fastest dimension rank */
          fast_dim = (int)ndims - 1;
  
          /* Set the local copy of the diminfo pointer */
          tdiminfo=iter->u.hyp.diminfo;
  
          /* Calculate the offset and block count for each dimension */
          for(i=0; i<ndims; i++) {
              if(tdiminfo[i].count==1) {
                  iter_offset[i]=iter->u.hyp.off[i]-tdiminfo[i].start;
                  iter_count[i]=0;
              } /* end if */
              else {
                  iter_offset[i]=(iter->u.hyp.off[i]-tdiminfo[i].start)%tdiminfo[i].stride;
                  iter_count[i]=(iter->u.hyp.off[i]-tdiminfo[i].start)/tdiminfo[i].stride;
              } /* end else */
          } /* end for */
  
          /* Loop through, advancing the offset & counts, until all the nelements are accounted for */
          while(nelem>0) {
              /* Start with the fastest changing dimension */
              temp_dim=fast_dim;
              while(temp_dim>=0) {
                  if(temp_dim==fast_dim) {
                      size_t actual_elem;     /* Actual # of elements advanced on each iteration through loop */
                      hsize_t block_elem;     /* Number of elements left in a block */
  
                      /* Compute the number of elements left in block */
                      block_elem=tdiminfo[temp_dim].block-iter_offset[temp_dim];
  
                      /* Compute the number of actual elements to advance */
                      actual_elem=(size_t)MIN(nelem,block_elem);
  
                      /* Move the iterator over as many elements as possible */
                      iter_offset[temp_dim]+=actual_elem;
  
                      /* Decrement the number of elements advanced */
                      nelem-=actual_elem;
                  } /* end if */
                  else {
                      /* Move to the next row in the current dimension */
                      iter_offset[temp_dim]++;
                  } /* end else */
  
                  /* If this block is still in the range of blocks to output for the dimension, break out of loop */
                  if(iter_offset[temp_dim]<tdiminfo[temp_dim].block)
                      break;
                  else {
                      /* Move to the next block in the current dimension */
                      iter_offset[temp_dim]=0;
                      iter_count[temp_dim]++;
  
                      /* If this block is still in the range of blocks to output for the dimension, break out of loop */
                      if(iter_count[temp_dim]<tdiminfo[temp_dim].count)
                          break;
                      else
                          iter_count[temp_dim]=0; /* reset back to the beginning of the line */
                  } /* end else */
  
                  /* Decrement dimension count */
                  temp_dim--;
              } /* end while */
          } /* end while */
  
          /* Translate current iter_offset and iter_count into iterator position */
          for(i=0; i<ndims; i++)
              iter->u.hyp.off[i]=tdiminfo[i].start+(tdiminfo[i].stride*iter_count[i])+iter_offset[i];
      } /* end if */
      /* Must be an irregular hyperslab selection */
      else {
          H5S_hyper_span_t *curr_span;    /* Current hyperslab span node */
          H5S_hyper_span_t **ispan;       /* Iterator's hyperslab span nodes */
          hsize_t *abs_arr;              /* Absolute hyperslab span position */
          int curr_dim;                   /* Temporary rank holder */
  
          /* Set the rank of the fastest changing dimension */
          ndims=iter->rank;
          fast_dim = (int)ndims - 1;
  
          /* Get the pointers to the current span info and span nodes */
          abs_arr=iter->u.hyp.off;
          ispan=iter->u.hyp.span;
  
          /* Loop through, advancing the span information, until all the nelements are accounted for */
          while(nelem>0) {
              /* Start at the fastest dim */
              curr_dim=fast_dim;
  
              /* Work back up through the dimensions */
              while(curr_dim>=0) {
                  /* Reset the current span */
                  curr_span=ispan[curr_dim];
  
                  /* Increment absolute position */
                  if(curr_dim==fast_dim) {
                      size_t actual_elem;     /* Actual # of elements advanced on each iteration through loop */
                      hsize_t span_elem;      /* Number of elements left in a span */
  
                      /* Compute the number of elements left in block */
                      span_elem=(curr_span->high-abs_arr[curr_dim])+1;
  
                      /* Compute the number of actual elements to advance */
                      actual_elem=(size_t)MIN(nelem,span_elem);
  
                      /* Move the iterator over as many elements as possible */
                      abs_arr[curr_dim]+=actual_elem;
  
                      /* Decrement the number of elements advanced */
                      nelem-=actual_elem;
                  } /* end if */
                  else {
                      /* Move to the next row in the current dimension */
                      abs_arr[curr_dim]++;
                  } /* end else */
  
                  /* Check if we are still within the span */
                  if(abs_arr[curr_dim]<=curr_span->high) {
                      break;
                  } /* end if */
                  /* If we walked off that span, advance to the next span */
                  else {
                      /* Advance span in this dimension */
                      curr_span=curr_span->next;
  
                      /* Check if we have a valid span in this dimension still */
                      if(curr_span!=NULL) {
                          /* Reset the span in the current dimension */
                          ispan[curr_dim]=curr_span;
  
                          /* Reset absolute position */
                          abs_arr[curr_dim]=curr_span->low;
  
                          break;
                      } /* end if */
                      else {
                          /* If we finished the span list in this dimension, decrement the dimension worked on and loop again */
                          curr_dim--;
                      } /* end else */
                  } /* end else */
              } /* end while */
  
              /* Check if we are finished with the spans in the tree */
              if(curr_dim>=0) {
                  /* Walk back down the iterator positions, reseting them */
                  while(curr_dim<fast_dim) {
                      HDassert(curr_span);
                      HDassert(curr_span->down);
                      HDassert(curr_span->down->head);
  
                      /* Increment current dimension */
                      curr_dim++;
  
                      /* Set the new span_info & span for this dimension */
                      ispan[curr_dim]=curr_span->down->head;
  
                      /* Advance span down the tree */
                      curr_span=curr_span->down->head;
  
                      /* Reset the absolute offset for the dim */
                      abs_arr[curr_dim]=curr_span->low;
                  } /* end while */
  
                  /* Verify that the curr_span points to the fastest dim */
                  HDassert(curr_span==ispan[fast_dim]);
              } /* end if */
          } /* end while */
      } /* end else */
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  } /* H5S_hyper_iter_next() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_hyper_iter_next_block
   *
   * Purpose:	Moves a hyperslab iterator to the beginning of the next sequence
   *      of elements to read.  Handles walking off the end in all dimensions.
   *
   * Return:	Success:	non-negative
   *		Failure:	negative
   *
   * Programmer:	Quincey Koziol
   *              Tuesday, June 3, 2003
   *
   * Modifications:
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_hyper_iter_next_block(H5S_sel_iter_t *iter)
  {
      unsigned ndims;     /* Number of dimensions of dataset */
      int fast_dim;       /* Rank of the fastest changing dimension for the dataspace */
      unsigned u;         /* Counters */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check for the special case of just one H5Sselect_hyperslab call made */
      /* (i.e. a regular hyperslab selection */
      if(iter->u.hyp.diminfo_valid) {
          const H5S_hyper_dim_t *tdiminfo;    /* Temporary pointer to diminfo information */
          hsize_t iter_offset[H5O_LAYOUT_NDIMS];
          hsize_t iter_count[H5O_LAYOUT_NDIMS];
          int temp_dim;  /* Temporary rank holder */
  
          /* Check if this is a "flattened" regular hyperslab selection */
          if(iter->u.hyp.iter_rank!=0 && iter->u.hyp.iter_rank<iter->rank) {
              /* Set the aliases for the dimension rank */
              ndims=iter->u.hyp.iter_rank;
          } /* end if */
          else {
              /* Set the aliases for the dimension rank */
              ndims=iter->rank;
          } /* end else */
  
          /* Set the fastest dimension rank */
          fast_dim = (int)ndims - 1;
  
          /* Set the local copy of the diminfo pointer */
          tdiminfo=iter->u.hyp.diminfo;
  
          /* Calculate the offset and block count for each dimension */
          for(u=0; u<ndims; u++) {
              if(tdiminfo[u].count==1) {
                  iter_offset[u]=iter->u.hyp.off[u]-tdiminfo[u].start;
                  iter_count[u]=0;
              } /* end if */
              else {
                  iter_offset[u]=(iter->u.hyp.off[u]-tdiminfo[u].start)%tdiminfo[u].stride;
                  iter_count[u]=(iter->u.hyp.off[u]-tdiminfo[u].start)/tdiminfo[u].stride;
              } /* end else */
          } /* end for */
  
          /* Advance one block */
          temp_dim=fast_dim; /* Start with the fastest changing dimension */
          while(temp_dim>=0) {
              if(temp_dim==fast_dim) {
                  /* Move iterator over current block */
                  iter_offset[temp_dim]+=tdiminfo[temp_dim].block;
              } /* end if */
              else {
                  /* Move to the next row in the current dimension */
                  iter_offset[temp_dim]++;
              } /* end else */
  
              /* If this block is still in the range of blocks to output for the dimension, break out of loop */
              if(iter_offset[temp_dim]<tdiminfo[temp_dim].block)
                  break;
              else {
                  /* Move to the next block in the current dimension */
                  iter_offset[temp_dim]=0;
                  iter_count[temp_dim]++;
  
                  /* If this block is still in the range of blocks to output for the dimension, break out of loop */
                  if(iter_count[temp_dim]<tdiminfo[temp_dim].count)
                      break;
                  else
                      iter_count[temp_dim]=0; /* reset back to the beginning of the line */
              } /* end else */
  
              /* Decrement dimension count */
              temp_dim--;
          } /* end while */
  
          /* Translate current iter_offset and iter_count into iterator position */
          for(u=0; u<ndims; u++)
              iter->u.hyp.off[u]=tdiminfo[u].start+(tdiminfo[u].stride*iter_count[u])+iter_offset[u];
      } /* end if */
      /* Must be an irregular hyperslab selection */
      else {
          H5S_hyper_span_t *curr_span;    /* Current hyperslab span node */
          H5S_hyper_span_t **ispan;       /* Iterator's hyperslab span nodes */
          hsize_t *abs_arr;              /* Absolute hyperslab span position */
          int curr_dim;                   /* Temporary rank holder */
  
          /* Set the rank of the fastest changing dimension */
          ndims = iter->rank;
          fast_dim = (int)ndims - 1;
  
          /* Get the pointers to the current span info and span nodes */
          abs_arr=iter->u.hyp.off;
          ispan=iter->u.hyp.span;
  
          /* Loop through, advancing the span information, until all the nelements are accounted for */
          curr_dim=fast_dim; /* Start at the fastest dim */
  
          /* Work back up through the dimensions */
          while(curr_dim>=0) {
              /* Reset the current span */
              curr_span=ispan[curr_dim];
  
              /* Increment absolute position */
              if(curr_dim==fast_dim) {
                  /* Move the iterator over rest of element in span */
                  abs_arr[curr_dim]=curr_span->high+1;
              } /* end if */
              else {
                  /* Move to the next row in the current dimension */
                  abs_arr[curr_dim]++;
              } /* end else */
  
              /* Check if we are still within the span */
              if(abs_arr[curr_dim]<=curr_span->high) {
                  break;
              } /* end if */
              /* If we walked off that span, advance to the next span */
              else {
                  /* Advance span in this dimension */
                  curr_span=curr_span->next;
  
                  /* Check if we have a valid span in this dimension still */
                  if(curr_span!=NULL) {
                      /* Reset the span in the current dimension */
                      ispan[curr_dim]=curr_span;
  
                      /* Reset absolute position */
                      abs_arr[curr_dim]=curr_span->low;
  
                      break;
                  } /* end if */
                  else {
                      /* If we finished the span list in this dimension, decrement the dimension worked on and loop again */
                      curr_dim--;
                  } /* end else */
              } /* end else */
          } /* end while */
  
          /* Check if we are finished with the spans in the tree */
          if(curr_dim>=0) {
              /* Walk back down the iterator positions, reseting them */
              while(curr_dim<fast_dim) {
                  HDassert(curr_span);
                  HDassert(curr_span->down);
                  HDassert(curr_span->down->head);
  
                  /* Increment current dimension */
                  curr_dim++;
  
                  /* Set the new span_info & span for this dimension */
                  ispan[curr_dim]=curr_span->down->head;
  
                  /* Advance span down the tree */
                  curr_span=curr_span->down->head;
  
                  /* Reset the absolute offset for the dim */
                  abs_arr[curr_dim]=curr_span->low;
              } /* end while */
  
              /* Verify that the curr_span points to the fastest dim */
              HDassert(curr_span == ispan[fast_dim]);
          } /* end if */
      } /* end else */
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  } /* H5S_hyper_iter_next() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_iter_release
   PURPOSE
      Release hyperslab selection iterator information for a dataspace
   USAGE
      herr_t H5S_hyper_iter_release(iter)
          H5S_sel_iter_t *iter;       IN: Pointer to selection iterator
   RETURNS
      Non-negative on success/Negative on failure
   DESCRIPTION
      Releases all information for a dataspace hyperslab selection iterator
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_iter_release (H5S_sel_iter_t *iter)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(iter);
  
  /* Release the information needed for non-regular hyperslab I/O */
      /* Free the copy of the selections span tree */
      if(iter->u.hyp.spans != NULL)
          H5S_hyper_free_span_info(iter->u.hyp.spans);
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_iter_release() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_new_span
   PURPOSE
      Make a new hyperslab span node
   USAGE
      H5S_hyper_span_t *H5S_hyper_new_span(low, high, down, next)
          hsize_t low, high;         IN: Low and high bounds for new span node
          H5S_hyper_span_info_t *down;     IN: Down span tree for new node
          H5S_hyper_span_t *next;     IN: Next span for new node
   RETURNS
      Pointer to next span node on success, NULL on failure
   DESCRIPTION
      Allocate and initialize a new hyperslab span node, filling in the low &
      high bounds, the down span and next span pointers also.  Increment the
      reference count of the 'down span' if applicable.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static H5S_hyper_span_t *
  H5S_hyper_new_span(hsize_t low, hsize_t high, H5S_hyper_span_info_t *down, H5S_hyper_span_t *next)
  {
      H5S_hyper_span_t *ret_value;
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Allocate a new span node */
      if(NULL == (ret_value = H5FL_MALLOC(H5S_hyper_span_t)))
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, NULL, "can't allocate hyperslab span")
  
      /* Copy the span's basic information */
      ret_value->low = low;
      ret_value->high = high;
      ret_value->nelem = (high - low) + 1;
      ret_value->pstride = 0;
      ret_value->down = down;
      ret_value->next = next;
  
      /* Increment the reference count of the 'down span' if there is one */
      if(ret_value->down)
          ret_value->down->count++;
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_new_span() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_span_precompute_helper
   PURPOSE
      Helper routine to precompute the nelem and pstrides in bytes.
   USAGE
      herr_t H5S_hyper_span_precompute_helper(span_info, elmt_size)
          H5S_hyper_span_info_t *span_info;      IN/OUT: Span tree to work on
          size_t elmt_size;                      IN: element size to work with
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Change the nelem and pstride values in the span tree from elements to
      bytes using the elmt_size parameter.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_span_precompute_helper (H5S_hyper_span_info_t *spans, size_t elmt_size)
  {
      H5S_hyper_span_t *span;     /* Hyperslab span */
      herr_t      ret_value = SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(spans);
  
      /* Check if we've already set this down span tree */
      if(spans->scratch!=(H5S_hyper_span_info_t *)~((size_t)NULL)) {
          /* Set the tree's scratch pointer */
          spans->scratch=(H5S_hyper_span_info_t *)~((size_t)NULL);
  
          /* Set the scratch pointers in all the nodes */
          span=spans->head;
  
          /* Loop over all the spans for this down span tree */
          while(span!=NULL) {
              /* If there are down spans, set their scratch value also */
              if(span->down!=NULL) {
                  if(H5S_hyper_span_precompute_helper(span->down,elmt_size)==FAIL)
                      HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "can't reset hyperslab scratch pointer")
              } /* end if */
  
              /* Change the nelem & pstride values into bytes */
              span->nelem *= elmt_size;
              span->pstride *= elmt_size;
  
              /* Advance to next span */
              span=span->next;
          } /* end while */
      } /* end if */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_span_precompute_helper() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_span_precompute
   PURPOSE
      Precompute the nelem and pstrides in bytes.
   USAGE
      herr_t H5S_hyper_span_precompute(span_info, elmt_size)
          H5S_hyper_span_info_t *span_info;      IN/OUT: Span tree to work on
          size_t elmt_size;                      IN: element size to work with
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Change the nelem and pstride values in the span tree from elements to
      bytes using the elmt_size parameter.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_span_precompute(H5S_hyper_span_info_t *spans, size_t elmt_size)
  {
      herr_t      ret_value = SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(spans);
  
      /* Call the helper routine to actually do the work */
      if(H5S_hyper_span_precompute_helper(spans, elmt_size) < 0)
          HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "can't precompute span info")
  
      /* Reset the scratch pointers for the next routine which needs them */
      H5S_hyper_span_scratch(spans, NULL);
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_span_precompute() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_span_scratch
   PURPOSE
      Set the scratch pointers on hyperslab span trees
   USAGE
      void H5S_hyper_span_scratch(span_info)
          H5S_hyper_span_info_t *span_info;      IN: Span tree to reset
   RETURNS
      <none>
   DESCRIPTION
      Set the scratch pointers on a hyperslab span tree.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static void
  H5S_hyper_span_scratch(H5S_hyper_span_info_t *spans, void *scr_value)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      HDassert(spans);
  
      /* Check if we've already set this down span tree */
      if(spans->scratch != scr_value) {
          H5S_hyper_span_t *span;             /* Hyperslab span */
  
          /* Set the tree's scratch pointer */
          spans->scratch = (H5S_hyper_span_info_t *)scr_value;
  
          /* Set the scratch pointers in all the nodes */
          span = spans->head;
          while(span != NULL) {
              /* If there are down spans, set their scratch value also */
              if(span->down != NULL)
                  H5S_hyper_span_scratch(span->down, scr_value);
  
              /* Advance to next span */
              span = span->next;
          } /* end while */
      } /* end if */
  
      FUNC_LEAVE_NOAPI_VOID
  }   /* H5S_hyper_span_scratch() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_copy_span_helper
   PURPOSE
      Helper routine to copy a hyperslab span tree
   USAGE
      H5S_hyper_span_info_t * H5S_hyper_copy_span_helper(spans)
          H5S_hyper_span_info_t *spans;      IN: Span tree to copy
   RETURNS
      Pointer to the copied span tree on success, NULL on failure
   DESCRIPTION
      Copy a hyperslab span tree, using reference counting as appropriate.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static H5S_hyper_span_info_t *
  H5S_hyper_copy_span_helper (H5S_hyper_span_info_t *spans)
  {
      H5S_hyper_span_t *span;         /* Hyperslab span */
      H5S_hyper_span_t *new_span;     /* Temporary hyperslab span */
      H5S_hyper_span_t *prev_span;    /* Previous hyperslab span */
      H5S_hyper_span_info_t *new_down;    /* New down span tree */
      H5S_hyper_span_info_t *ret_value;
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(spans);
  
      /* Check if the span tree was already copied */
      if(spans->scratch != NULL && spans->scratch != (H5S_hyper_span_info_t *)~((size_t)NULL)) {
          /* Just return the value of the already copied span tree */
          ret_value = spans->scratch;
  
          /* Increment the reference count of the span tree */
          ret_value->count++;
      } /* end if */
      else {
          /* Allocate a new span_info node */
          if(NULL == (ret_value = H5FL_MALLOC(H5S_hyper_span_info_t)))
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, NULL, "can't allocate hyperslab span info")
  
          /* Copy the span_info information */
          ret_value->count = 1;
          ret_value->scratch = NULL;
          ret_value->head = NULL;
  
          /* Set the scratch pointer in the node being copied to the newly allocated node */
          spans->scratch = ret_value;
  
          /* Copy over the nodes in the span list */
          span = spans->head;
          prev_span = NULL;
          while(span != NULL) {
              /* Allocate a new node */
              if(NULL == (new_span = H5S_hyper_new_span(span->low, span->high, NULL, NULL)))
                  HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, NULL, "can't allocate hyperslab span")
  
              /* Append to list of spans */
              if(NULL == prev_span)
                  ret_value->head = new_span;
              else
                  prev_span->next = new_span;
  
              /* Copy the pstride */
              new_span->pstride = span->pstride;
  
              /* Recurse to copy the 'down' spans, if there are any */
              if(span->down != NULL) {
                  if(NULL == (new_down = H5S_hyper_copy_span_helper(span->down)))
                      HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, NULL, "can't copy hyperslab spans")
                  new_span->down = new_down;
              } /* end if */
  
              /* Update the previous (new) span */
              prev_span = new_span;
  
              /* Advance to next span */
              span = span->next;
          } /* end while */
      } /* end else */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_copy_span_helper() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_copy_span
   PURPOSE
      Copy a hyperslab span tree
   USAGE
      H5S_hyper_span_info_t * H5S_hyper_copy_span(span_info)
          H5S_hyper_span_info_t *span_info;      IN: Span tree to copy
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Copy a hyperslab span tree, using reference counting as appropriate.
      (Which means that just the nodes in the top span tree are duplicated and
      the reference counts of their 'down spans' are just incremented)
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static H5S_hyper_span_info_t *
  H5S_hyper_copy_span(H5S_hyper_span_info_t *spans)
  {
      H5S_hyper_span_info_t *ret_value;
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(spans);
  
      /* Copy the hyperslab span tree */
      if(NULL == (ret_value = H5S_hyper_copy_span_helper(spans)))
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, NULL, "can't copy hyperslab span tree")
  
      /* Reset the scratch pointers for the next routine which needs them */
      H5S_hyper_span_scratch(spans, NULL);
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_copy_span() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_cmp_spans
   PURPOSE
      Check if two hyperslab slabs are the same
   USAGE
      htri_d H5S_hyper_cmp_spans(span1, span2)
          H5S_hyper_span_t *span1;    IN: First span tree to compare
          H5S_hyper_span_t *span2;    IN: Second span tree to compare
   RETURNS
      TRUE (1) or FALSE (0) on success, negative on failure
   DESCRIPTION
      Compare two hyperslab slabs to determine if they refer to the same
      selection.  If span1 & span2 are both NULL, that counts as equal
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static htri_t
  H5S_hyper_cmp_spans (H5S_hyper_span_info_t *span_info1, H5S_hyper_span_info_t *span_info2)
  {
      H5S_hyper_span_t *span1;
      H5S_hyper_span_t *span2;
      htri_t nest=FAIL;
      htri_t ret_value=FAIL;
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check for redundant comparison */
      if(span_info1==span_info2)
          ret_value=TRUE;
      else {
          /* Check for both spans being NULL */
          if(span_info1==NULL && span_info2==NULL)
              ret_value=TRUE;
          else {
              /* Check for one span being NULL */
              if(span_info1==NULL || span_info2==NULL)
                  ret_value=FALSE;
              else {
                  /* Get the pointers to the actual lists of spans */
                  span1=span_info1->head;
                  span2=span_info2->head;
  
                  /* Sanity checking */
                  HDassert(span1);
                  HDassert(span2);
  
                  /* infinite loop which must be broken out of */
                  while (1) {
                      /* Check for both spans being NULL */
                      if(span1==NULL && span2==NULL) {
                          ret_value=TRUE;
                          break;
                      } /* end if */
                      else {
                          /* Check for one span being NULL */
                          if(span1==NULL || span2==NULL) {
                              ret_value=FALSE;
                              break;
                          } /* end if */
                          else {
                              /* Check if the actual low & high span information is the same */
                              if(span1->low!=span2->low || span1->high!=span2->high) {
                                  ret_value=FALSE;
                                  break;
                              } /* end if */
                              else {
                                  if(span1->down!=NULL || span2!=NULL) {
                                      if((nest=H5S_hyper_cmp_spans(span1->down,span2->down))==FAIL) {
                                          ret_value=FAIL;
                                          break;
                                      } /* end if */
                                      else {
                                          if(nest==FALSE) {
                                              ret_value=FALSE;
                                              break;
                                          } /* end if */
                                          else {
                                              /* Keep going... */
                                          } /* end else */
                                      } /* end else */
                                  } /* end if */
                                  else {
                                      /* Keep going... */
                                  } /* end else */
                              } /* end else */
                          } /* end else */
                      } /* end else */
  
                      /* Advance to the next nodes in the span list */
                      span1=span1->next;
                      span2=span2->next;
                  } /* end while */
              } /* end else */
          } /* end else */
      } /* end else */
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_cmp_spans() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_free_span_info
   PURPOSE
      Free a hyperslab span info node
   USAGE
      herr_t H5S_hyper_free_span_info(span_info)
          H5S_hyper_span_info_t *span_info;      IN: Span info node to free
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Free a hyperslab span info node, along with all the span nodes and the
      'down spans' from the nodes, if reducing their reference count to zero
      indicates it is appropriate to do so.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_free_span_info (H5S_hyper_span_info_t *span_info)
  {
      H5S_hyper_span_t *span, *next_span;
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(span_info);
  
      /* Decrement the span tree's reference count */
      span_info->count--;
  
      /* Free the span tree if the reference count drops to zero */
      if(span_info->count==0) {
  
          /* Work through the list of spans pointed to by this 'info' node */
          span=span_info->head;
          while(span!=NULL) {
              next_span=span->next;
              if(H5S_hyper_free_span(span)<0)
                  HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release hyperslab span")
              span=next_span;
          } /* end while */
  
          /* Free this span info */
          span_info = H5FL_FREE(H5S_hyper_span_info_t, span_info);
      } /* end if */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_free_span_info() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_free_span
   PURPOSE
      Free a hyperslab span node
   USAGE
      herr_t H5S_hyper_free_span(span)
          H5S_hyper_span_t *span;      IN: Span node to free
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Free a hyperslab span node, along with the 'down spans' from the node,
      if reducing their reference count to zero indicates it is appropriate to
      do so.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_free_span (H5S_hyper_span_t *span)
  {
      herr_t ret_value=SUCCEED;
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(span);
  
      /* Decrement the reference count of the 'down spans', freeing them if appropriate */
      if(span->down!=NULL) {
          if(H5S_hyper_free_span_info(span->down)<0)
              HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release hyperslab span tree")
      } /* end if */
  
      /* Free this span */
      span = H5FL_FREE(H5S_hyper_span_t, span);
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_free_span() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_copy
   PURPOSE
      Copy a selection from one dataspace to another
   USAGE
      herr_t H5S_hyper_copy(dst, src)
          H5S_t *dst;  OUT: Pointer to the destination dataspace
          H5S_t *src;  IN: Pointer to the source dataspace
   RETURNS
      Non-negative on success/Negative on failure
   DESCRIPTION
      Copies all the hyperslab selection information from the source
      dataspace to the destination dataspace.
  
      If the SHARE_SELECTION flag is set, then the selection can be shared
      between the source and destination dataspaces.  (This should only occur in
      situations where the destination dataspace will immediately change to a new
      selection)
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_copy (H5S_t *dst, const H5S_t *src, hbool_t share_selection)
  {
      H5S_hyper_sel_t *dst_hslab;         /* Pointer to destination hyperslab info */
      const H5S_hyper_sel_t *src_hslab;   /* Pointer to source hyperslab info */
      herr_t ret_value=SUCCEED;   /* return value */
  
      FUNC_ENTER_NOAPI(FAIL)
  
      HDassert(src);
      HDassert(dst);
  
      /* Allocate space for the hyperslab selection information */
      if(NULL == (dst->select.sel_info.hslab = H5FL_MALLOC(H5S_hyper_sel_t)))
          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab info")
  
      /* Set temporary pointers */
      dst_hslab=dst->select.sel_info.hslab;
      src_hslab=src->select.sel_info.hslab;
  
      /* Copy the hyperslab information */
      dst_hslab->diminfo_valid=src_hslab->diminfo_valid;
      if(src_hslab->diminfo_valid) {
          size_t u;       /* Local index variable */
  
          for(u=0; u<src->extent.rank; u++) {
              dst_hslab->opt_diminfo[u]=src_hslab->opt_diminfo[u];
              dst_hslab->app_diminfo[u]=src_hslab->app_diminfo[u];
          } /* end for */
      } /* end if */
      dst->select.sel_info.hslab->span_lst=src->select.sel_info.hslab->span_lst;
  
      /* Check if there is hyperslab span information to copy */
      /* (Regular hyperslab information is copied with the selection structure) */
      if(src->select.sel_info.hslab->span_lst!=NULL) {
          if(share_selection) {
              /* Share the source's span tree by incrementing the reference count on it */
              dst->select.sel_info.hslab->span_lst->count++;
          } /* end if */
          else
              /* Copy the hyperslab span information */
              dst->select.sel_info.hslab->span_lst = H5S_hyper_copy_span(src->select.sel_info.hslab->span_lst);
      } /* end if */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  } /* end H5S_hyper_copy() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_is_valid_helper
   PURPOSE
      Check whether the selection fits within the extent, with the current
      offset defined.
   USAGE
      htri_t H5S_hyper_is_valid_helper(spans, offset, rank);
          const H5S_hyper_span_info_t *spans; IN: Pointer to current hyperslab span tree
          const hssize_t *offset;             IN: Pointer to offset array
          const hsize_t *size;                IN: Pointer to size array
          hsize_t rank;                       IN: Current rank looking at
   RETURNS
      TRUE if the selection fits within the extent, FALSE if it does not and
          Negative on an error.
   DESCRIPTION
      Determines if the current selection at the current offet fits within the
      extent for the dataspace.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static htri_t
  H5S_hyper_is_valid_helper (const H5S_hyper_span_info_t *spans, const hssize_t *offset, const hsize_t *size, hsize_t rank)
  {
      H5S_hyper_span_t *curr;     /* Hyperslab information nodes */
      htri_t tmp;                 /* temporary return value */
      htri_t ret_value=TRUE;      /* return value */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      HDassert(spans);
      HDassert(offset);
      HDassert(size);
      HDassert(rank < H5O_LAYOUT_NDIMS);
  
      /* Check each point to determine whether selection+offset is within extent */
      curr=spans->head;
      while(curr!=NULL && ret_value==TRUE) {
          /* Check if an offset has been defined */
          /* Bounds check the selected point + offset against the extent */
          if((((hssize_t)curr->low+offset[rank])>=(hssize_t)size[rank])
                  || (((hssize_t)curr->low+offset[rank])<0)
                  || (((hssize_t)curr->high+offset[rank])>=(hssize_t)size[rank])
                  || (((hssize_t)curr->high+offset[rank])<0)) {
              ret_value=FALSE;
              break;
          } /* end if */
  
          /* Recurse if this node has down spans */
          if(curr->down!=NULL) {
              if((tmp=H5S_hyper_is_valid_helper(curr->down,offset,size,rank+1))!=TRUE) {
                  ret_value=tmp;
                  break;
              } /* end if */
          } /* end if */
  
          /* Advance to next node */
          curr=curr->next;
      } /* end while */
  
      FUNC_LEAVE_NOAPI(ret_value)
  } /* end H5S_hyper_is_valid_helper() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_is_valid
   PURPOSE
      Check whether the selection fits within the extent, with the current
      offset defined.
   USAGE
      htri_t H5S_hyper_is_valid(space);
          H5S_t *space;             IN: Dataspace pointer to query
   RETURNS
      TRUE if the selection fits within the extent, FALSE if it does not and
          Negative on an error.
   DESCRIPTION
      Determines if the current selection at the current offet fits within the
      extent for the dataspace.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static htri_t
  H5S_hyper_is_valid (const H5S_t *space)
  {
      unsigned u;                    /* Counter */
      htri_t ret_value=TRUE;      /* return value */
  
      FUNC_ENTER_NOAPI_NOERR
  
      HDassert(space);
  
      /* Check for a "regular" hyperslab selection */
      if(space->select.sel_info.hslab->diminfo_valid) {
          const H5S_hyper_dim_t *diminfo=space->select.sel_info.hslab->opt_diminfo; /* local alias for diminfo */
          hssize_t end;      /* The high bound of a region in a dimension */
  
          /* Check each dimension */
          for(u=0; u<space->extent.rank; u++) {
              /* if block or count is zero, then can skip the test since */
              /* no data point is chosen */
              if (diminfo[u].count && diminfo[u].block) {
                  /* Bounds check the start point in this dimension */
                  if(((hssize_t)diminfo[u].start+space->select.offset[u])<0 ||
                          ((hssize_t)diminfo[u].start+space->select.offset[u])>=(hssize_t)space->extent.size[u])
                      HGOTO_DONE(FALSE)
  
                  /* Compute the largest location in this dimension */
                  end=(hssize_t)(diminfo[u].start+diminfo[u].stride*(diminfo[u].count-1)+(diminfo[u].block-1))+space->select.offset[u];
  
                  /* Bounds check the end point in this dimension */
                  if(end<0 || end>=(hssize_t)space->extent.size[u])
                      HGOTO_DONE(FALSE)
              } /* end if */
          } /* end for */
      } /* end if */
      else {
          /* Call the recursive routine to validate the span tree */
          ret_value=H5S_hyper_is_valid_helper(space->select.sel_info.hslab->span_lst,space->select.offset,space->extent.size,(hsize_t)0);
      } /* end else */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  } /* end H5S_hyper_is_valid() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_span_nblocks
   PURPOSE
      Count the number of blocks in a span tree
   USAGE
      hsize_t H5S_hyper_span_nblocks(spans)
          const H5S_hyper_span_info_t *spans; IN: Hyperslab span tree to count elements of
   RETURNS
      Number of blocks in span tree on success; negative on failure
   DESCRIPTION
      Counts the number of blocks described by the spans in a span tree.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static hsize_t
  H5S_hyper_span_nblocks(H5S_hyper_span_info_t *spans)
  {
      H5S_hyper_span_t *span;     /* Hyperslab span */
      hsize_t ret_value = 0;      /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Count the number of elements in the span tree */
      if(spans != NULL) {
          span = spans->head;
          while(span != NULL) {
              /* If there are down spans, add the total down span blocks */
              if(span->down!=NULL)
                  ret_value += H5S_hyper_span_nblocks(span->down);
              /* If there are no down spans, just count the block in this span */
              else
                  ret_value++;
  
              /* Advance to next span */
              span = span->next;
          } /* end while */
      } /* end else */
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_span_nblocks() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_get_select_hyper_nblocks
   PURPOSE
      Get the number of hyperslab blocks in current hyperslab selection
   USAGE
      hsize_t H5S_get_select_hyper_nblocks(space)
          H5S_t *space;             IN: Dataspace ptr of selection to query
   RETURNS
      The number of hyperslab blocks in selection on success, negative on failure
   DESCRIPTION
      Returns the number of hyperslab blocks in current selection for dataspace.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static hsize_t
  H5S_get_select_hyper_nblocks(H5S_t *space)
  {
      hsize_t ret_value;         /* return value */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      HDassert(space);
  
      /* Check for a "regular" hyperslab selection */
      if(space->select.sel_info.hslab->diminfo_valid) {
          unsigned u;                 /* Local index variable */
  
          /* Check each dimension */
          for(ret_value = 1, u = 0; u < space->extent.rank; u++)
              ret_value *= space->select.sel_info.hslab->app_diminfo[u].count;
      } /* end if */
      else
          ret_value = H5S_hyper_span_nblocks(space->select.sel_info.hslab->span_lst);
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_get_select_hyper_nblocks() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5Sget_select_hyper_nblocks
   PURPOSE
      Get the number of hyperslab blocks in current hyperslab selection
   USAGE
      hssize_t H5Sget_select_hyper_nblocks(dsid)
          hid_t dsid;             IN: Dataspace ID of selection to query
   RETURNS
      The number of hyperslab blocks in selection on success, negative on failure
   DESCRIPTION
      Returns the number of hyperslab blocks in current selection for dataspace.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  hssize_t
  H5Sget_select_hyper_nblocks(hid_t spaceid)
  {
      H5S_t *space;               /* Dataspace to modify selection of */
      hssize_t ret_value;         /* return value */
  
      FUNC_ENTER_API(FAIL)
      H5TRACE1("Hs", "i", spaceid);
  
      /* Check args */
      if(NULL == (space = (H5S_t *)H5I_object_verify(spaceid, H5I_DATASPACE)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space")
      if(H5S_GET_SELECT_TYPE(space) != H5S_SEL_HYPERSLABS)
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a hyperslab selection")
  
      ret_value = (hssize_t)H5S_get_select_hyper_nblocks(space);
  
  done:
      FUNC_LEAVE_API(ret_value)
  }   /* H5Sget_select_hyper_nblocks() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_serial_size
   PURPOSE
      Determine the number of bytes needed to store the serialized hyperslab
          selection information.
   USAGE
      hssize_t H5S_hyper_serial_size(space)
          H5S_t *space;             IN: Dataspace pointer to query
   RETURNS
      The number of bytes required on success, negative on an error.
   DESCRIPTION
      Determines the number of bytes required to serialize the current hyperslab
      selection information for storage on disk.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static hssize_t
  H5S_hyper_serial_size(const H5S_t *space)
  {
      unsigned u;                 /* Counter */
      hsize_t block_count;       /* block counter for regular hyperslabs */
      hssize_t ret_value;         /* return value */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      HDassert(space);
  
      /* Basic number of bytes required to serialize hyperslab selection:
       *  <type (4 bytes)> + <version (4 bytes)> + <padding (4 bytes)> +
       *      <length (4 bytes)> + <rank (4 bytes)> + <# of blocks (4 bytes)> = 24 bytes
       */
      ret_value = 24;
  
      /* Check for a "regular" hyperslab selection */
      if(space->select.sel_info.hslab->diminfo_valid) {
          /* Check each dimension */
          for(block_count = 1, u = 0; u < space->extent.rank; u++)
              block_count *= space->select.sel_info.hslab->opt_diminfo[u].count;
      } /* end if */
      else
          /* Spin through hyperslab spans, adding 8 * rank bytes for each block */
          block_count = H5S_hyper_span_nblocks(space->select.sel_info.hslab->span_lst);
  
      H5_CHECK_OVERFLOW((8 * space->extent.rank * block_count), hsize_t, hssize_t);
      ret_value += (hssize_t)(8 * block_count * space->extent.rank);
  
      FUNC_LEAVE_NOAPI(ret_value)
  } /* end H5S_hyper_serial_size() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_serialize_helper
   PURPOSE
      Serialize the current selection into a user-provided buffer.
   USAGE
      herr_t H5S_hyper_serialize_helper(spans, start, end, rank, buf)
          H5S_hyper_span_info_t *spans;   IN: Hyperslab span tree to serialize
          hssize_t start[];       IN/OUT: Accumulated start points
          hssize_t end[];         IN/OUT: Accumulated end points
          hsize_t rank;           IN: Current rank looking at
          uint8 *buf;             OUT: Buffer to put serialized selection into
   RETURNS
      Non-negative on success/Negative on failure
   DESCRIPTION
      Serializes the current element selection into a buffer.  (Primarily for
      storing on disk).
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_serialize_helper (const H5S_hyper_span_info_t *spans, hsize_t *start, hsize_t *end, hsize_t rank, uint8_t **buf)
  {
      H5S_hyper_span_t *curr;     /* Pointer to current hyperslab span */
      hsize_t u;                  /* Index variable */
      herr_t ret_value=SUCCEED;  /* return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Sanity checks */
      HDassert(spans);
      HDassert(start);
      HDassert(end);
      HDassert(rank < H5O_LAYOUT_NDIMS);
      HDassert(buf && *buf);
  
      /* Walk through the list of spans, recursing or outputing them */
      curr=spans->head;
      while(curr!=NULL) {
          /* Recurse if this node has down spans */
          if(curr->down!=NULL) {
              /* Add the starting and ending points for this span to the list */
              start[rank]=curr->low;
              end[rank]=curr->high;
  
              /* Recurse down to the next dimension */
              if(H5S_hyper_serialize_helper(curr->down,start,end,rank+1,buf)<0)
                  HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release hyperslab spans")
          } /* end if */
          else {
              /* Encode all the previous dimensions starting & ending points */
  
              /* Encode previous starting points */
              for(u=0; u<rank; u++)
                  UINT32ENCODE(*buf, (uint32_t)start[u]);
  
              /* Encode starting point for this span */
              UINT32ENCODE(*buf, (uint32_t)curr->low);
  
              /* Encode previous ending points */
              for(u=0; u<rank; u++)
                  UINT32ENCODE(*buf, (uint32_t)end[u]);
  
              /* Encode starting point for this span */
              UINT32ENCODE(*buf, (uint32_t)curr->high);
          } /* end else */
  
          /* Advance to next node */
          curr=curr->next;
      } /* end while */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_serialize_helper() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_serialize
   PURPOSE
      Serialize the current selection into a user-provided buffer.
   USAGE
      herr_t H5S_hyper_serialize(space, buf)
          H5S_t *space;           IN: Dataspace pointer of selection to serialize
          uint8 *buf;             OUT: Buffer to put serialized selection into
   RETURNS
      Non-negative on success/Negative on failure
   DESCRIPTION
      Serializes the current element selection into a buffer.  (Primarily for
      storing on disk).
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_serialize (const H5S_t *space, uint8_t *buf)
  {
      const H5S_hyper_dim_t *diminfo;         /* Alias for dataspace's diminfo information */
      hsize_t tmp_count[H5O_LAYOUT_NDIMS];    /* Temporary hyperslab counts */
      hsize_t offset[H5O_LAYOUT_NDIMS];      /* Offset of element in dataspace */
      hsize_t start[H5O_LAYOUT_NDIMS];   /* Location of start of hyperslab */
      hsize_t end[H5O_LAYOUT_NDIMS];     /* Location of end of hyperslab */
      hsize_t temp_off;            /* Offset in a given dimension */
      uint8_t *lenp;          /* pointer to length location for later storage */
      uint32_t len = 0;       /* number of bytes used */
      hsize_t block_count;    /* block counter for regular hyperslabs */
      unsigned fast_dim;      /* Rank of the fastest changing dimension for the dataspace */
      unsigned ndims;         /* Rank of the dataspace */
      int done;               /* Whether we are done with the iteration */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      HDassert(space);
  
      /* Store the preamble information */
      UINT32ENCODE(buf, (uint32_t)H5S_GET_SELECT_TYPE(space));  /* Store the type of selection */
      UINT32ENCODE(buf, (uint32_t)1);  /* Store the version number */
      UINT32ENCODE(buf, (uint32_t)0);  /* Store the un-used padding */
      lenp = buf;           /* keep the pointer to the length location for later */
      buf += 4;             /* skip over space for length */
  
      /* Encode number of dimensions */
      UINT32ENCODE(buf, (uint32_t)space->extent.rank);
      len += 4;
  
      /* Check for a "regular" hyperslab selection */
      if(space->select.sel_info.hslab->diminfo_valid) {
          unsigned u;     /* Local counting variable */
  
          /* Set some convienence values */
          ndims = space->extent.rank;
          fast_dim = ndims - 1;
          diminfo=space->select.sel_info.hslab->opt_diminfo;
  
          /* Check each dimension */
          for(block_count = 1, u = 0; u < ndims; u++)
              block_count *= diminfo[u].count;
  
          /* Encode number of hyperslabs */
          H5_CHECK_OVERFLOW(block_count, hsize_t, uint32_t);
          UINT32ENCODE(buf, (uint32_t)block_count);
          len+=4;
  
          /* Now serialize the information for the regular hyperslab */
  
          /* Build the tables of count sizes as well as the initial offset */
          for(u = 0; u < ndims; u++) {
              tmp_count[u] = diminfo[u].count;
              offset[u] = diminfo[u].start;
          } /* end for */
  
          /* We're not done with the iteration */
          done=0;
  
          /* Go iterate over the hyperslabs */
          while(done==0) {
              /* Iterate over the blocks in the fastest dimension */
              while(tmp_count[fast_dim]>0) {
                  /* Add 8 bytes times the rank for each hyperslab selected */
                  len+=8*ndims;
  
                  /* Encode hyperslab starting location */
                  for(u = 0; u < ndims; u++)
                      UINT32ENCODE(buf, (uint32_t)offset[u]);
  
                  /* Encode hyperslab ending location */
                  for(u = 0; u < ndims; u++)
                      UINT32ENCODE(buf, (uint32_t)(offset[u] + (diminfo[u].block - 1)));
  
                  /* Move the offset to the next sequence to start */
                  offset[fast_dim]+=diminfo[fast_dim].stride;
  
                  /* Decrement the block count */
                  tmp_count[fast_dim]--;
              } /* end while */
  
              /* Work on other dimensions if necessary */
              if(fast_dim > 0) {
                  int temp_dim;           /* Temporary rank holder */
  
                  /* Reset the block counts */
                  tmp_count[fast_dim]=diminfo[fast_dim].count;
  
                  /* Bubble up the decrement to the slower changing dimensions */
                  temp_dim = (int)fast_dim - 1;
                  while(temp_dim >= 0 && done == 0) {
                      /* Decrement the block count */
                      tmp_count[temp_dim]--;
  
                      /* Check if we have more blocks left */
                      if(tmp_count[temp_dim] > 0)
                          break;
  
                      /* Check for getting out of iterator */
                      if(temp_dim == 0)
                          done = 1;
  
                      /* Reset the block count in this dimension */
                      tmp_count[temp_dim] = diminfo[temp_dim].count;
  
                      /* Wrapped a dimension, go up to next dimension */
                      temp_dim--;
                  } /* end while */
              } /* end if */
              else
                  break;  /* Break out now, for 1-D selections */
  
              /* Re-compute offset array */
              for(u = 0; u < ndims; u++) {
                  temp_off = diminfo[u].start + diminfo[u].stride * (diminfo[u].count - tmp_count[u]);
                  offset[u] = temp_off;
              } /* end for */
          } /* end while */
      } /* end if */
      else {
          /* Encode number of hyperslabs */
          block_count = H5S_hyper_span_nblocks(space->select.sel_info.hslab->span_lst);
          H5_CHECK_OVERFLOW(block_count, hsize_t, uint32_t);
          UINT32ENCODE(buf, (uint32_t)block_count);
          len+=4;
  
          /* Add 8 bytes times the rank for each hyperslab selected */
          H5_CHECK_OVERFLOW((8 * space->extent.rank * block_count), hsize_t, size_t);
          len += (size_t)(8 * space->extent.rank * block_count);
  
          /* Encode each hyperslab in selection */
          H5S_hyper_serialize_helper(space->select.sel_info.hslab->span_lst, start, end, (hsize_t)0, &buf);
      } /* end else */
  
      /* Encode length */
      UINT32ENCODE(lenp, (uint32_t)len);  /* Store the length of the extra information */
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_serialize() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_deserialize
   PURPOSE
      Deserialize the current selection from a user-provided buffer.
   USAGE
      herr_t H5S_hyper_deserialize(space, buf)
          H5S_t *space;           IN/OUT: Dataspace pointer to place selection into
          uint8 *buf;             IN: Buffer to retrieve serialized selection from
   RETURNS
      Non-negative on success/Negative on failure
   DESCRIPTION
      Deserializes the current selection into a buffer.  (Primarily for retrieving
      from disk).
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_deserialize (H5S_t *space, const uint8_t *buf)
  {
      uint32_t rank;           	/* rank of points */
      size_t num_elem=0;      	/* number of elements in selection */
      hsize_t start[H5O_LAYOUT_NDIMS];	/* hyperslab start information */
      hsize_t end[H5O_LAYOUT_NDIMS];	/* hyperslab end information */
      hsize_t stride[H5O_LAYOUT_NDIMS];   /* hyperslab stride information */
      hsize_t count[H5O_LAYOUT_NDIMS];    /* hyperslab count information */
      hsize_t block[H5O_LAYOUT_NDIMS];    /* hyperslab block information */
      hsize_t *tstart=NULL;	/* temporary hyperslab pointers */
      hsize_t *tend=NULL;		/* temporary hyperslab pointers */
      hsize_t *tstride=NULL;	/* temporary hyperslab pointers */
      hsize_t *tcount=NULL;	/* temporary hyperslab pointers */
      hsize_t *tblock=NULL;	/* temporary hyperslab pointers */
      unsigned i,j;              	/* local counting variables */
      herr_t ret_value=FAIL;  	/* return value */
  
      FUNC_ENTER_NOAPI(FAIL)
  
      /* Check args */
      HDassert(space);
      HDassert(buf);
  
      /* Deserialize slabs to select */
      buf+=16;    /* Skip over selection header */
      UINT32DECODE(buf,rank);  /* decode the rank of the point selection */
      if(rank!=space->extent.rank)
          HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "rank of pointer does not match dataspace")
      UINT32DECODE(buf,num_elem);  /* decode the number of points */
  
      /* Set the count & stride for all blocks */
      for(tcount=count,tstride=stride,j=0; j<rank; j++,tstride++,tcount++) {
          *tcount=1;
          *tstride=1;
      } /* end for */
  
      /* Retrieve the coordinates from the buffer */
      for(i=0; i<num_elem; i++) {
          /* Decode the starting points */
          for(tstart=start,j=0; j<rank; j++,tstart++)
              UINT32DECODE(buf, *tstart);
  
          /* Decode the ending points */
          for(tend=end,j=0; j<rank; j++,tend++)
              UINT32DECODE(buf, *tend);
  
          /* Change the ending points into blocks */
          for(tblock=block,tstart=start,tend=end,j=0; j<(unsigned)rank; j++,tstart++,tend++,tblock++)
              *tblock=(*tend-*tstart)+1;
  
          /* Select or add the hyperslab to the current selection */
          if((ret_value=H5S_select_hyperslab(space,(i==0 ? H5S_SELECT_SET : H5S_SELECT_OR),start,stride,count,block))<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't change selection")
      } /* end for */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_deserialize() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_span_blocklist
   PURPOSE
      Get a list of hyperslab blocks currently selected
   USAGE
      herr_t H5S_hyper_span_blocklist(spans, start, end, rank, startblock, numblocks, buf)
          H5S_hyper_span_info_t *spans;   IN: Dataspace pointer of selection to query
          hsize_t start[];       IN/OUT: Accumulated start points
          hsize_t end[];         IN/OUT: Accumulated end points
          hsize_t rank;           IN: Rank of dataspace
          hsize_t *startblock;    IN/OUT: Hyperslab block to start with
          hsize_t *numblocks;     IN/OUT: Number of hyperslab blocks to get
          hsize_t **buf;          OUT: List of hyperslab blocks selected
   RETURNS
      Non-negative on success/Negative on failure
   DESCRIPTION
          Puts a list of the hyperslab blocks into the user's buffer.  The blocks
      start with the '*startblock'th block in the list of blocks and put
      '*numblocks' number of blocks into the user's buffer (or until the end of
      the list of blocks, whichever happens first)
          The block coordinates have the same dimensionality (rank) as the
      dataspace they are located within.  The list of blocks is formatted as
      follows: <"start" coordinate> immediately followed by <"opposite" corner
      coordinate>, followed by the next "start" and "opposite" coordinate, etc.
      until all the block information requested has been put into the user's
      buffer.
          No guarantee of any order of the blocks is implied.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_span_blocklist(H5S_hyper_span_info_t *spans, hsize_t start[], hsize_t end[], hsize_t rank, hsize_t *startblock, hsize_t *numblocks, hsize_t **buf)
  {
      H5S_hyper_span_t *curr;     /* Pointer to current hyperslab span */
      hsize_t u;                  /* Index variable */
      herr_t ret_value = SUCCEED; /* return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Sanity checks */
      HDassert(spans);
      HDassert(rank < H5O_LAYOUT_NDIMS);
      HDassert(start);
      HDassert(end);
      HDassert(startblock);
      HDassert(numblocks && *numblocks > 0);
      HDassert(buf && *buf);
  
      /* Walk through the list of spans, recursing or outputing them */
      curr = spans->head;
      while(curr != NULL && *numblocks > 0) {
          /* Recurse if this node has down spans */
          if(curr->down != NULL) {
              /* Add the starting and ending points for this span to the list */
              start[rank] = curr->low;
              end[rank] = curr->high;
  
              /* Recurse down to the next dimension */
              if(H5S_hyper_span_blocklist(curr->down, start, end, (rank + 1), startblock, numblocks, buf) < 0)
                  HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release hyperslab spans")
          } /* end if */
          else {
              /* Skip this block if we haven't skipped all the startblocks yet */
              if(*startblock > 0) {
                  /* Decrement the starting block */
                  (*startblock)--;
              } /* end if */
              /* Process this block */
              else {
                  /* Encode all the previous dimensions starting & ending points */
  
                  /* Copy previous starting points */
                  for(u = 0; u < rank; u++, (*buf)++)
                      HDmemcpy(*buf, &start[u], sizeof(hsize_t));
  
                  /* Copy starting point for this span */
                  HDmemcpy(*buf, &curr->low, sizeof(hsize_t));
                  (*buf)++;
  
                  /* Copy previous ending points */
                  for(u = 0; u < rank; u++, (*buf)++)
                      HDmemcpy(*buf, &end[u], sizeof(hsize_t));
  
                  /* Copy starting point for this span */
                  HDmemcpy(*buf, &curr->high, sizeof(hsize_t));
                  (*buf)++;
  
                  /* Decrement the number of blocks processed */
                  (*numblocks)--;
              } /* end else */
          } /* end else */
  
          /* Advance to next node */
          curr = curr->next;
      } /* end while */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_span_blocklist() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_get_select_hyper_blocklist
   PURPOSE
      Get the list of hyperslab blocks currently selected
   USAGE
      herr_t H5S_get_select_hyper_blocklist(space, startblock, numblocks, buf)
          H5S_t *space;           IN: Dataspace pointer of selection to query
          hsize_t startblock;     IN: Hyperslab block to start with
          hsize_t numblocks;      IN: Number of hyperslab blocks to get
          hsize_t *buf;           OUT: List of hyperslab blocks selected
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
          Puts a list of the hyperslab blocks into the user's buffer.  The blocks
      start with the 'startblock'th block in the list of blocks and put
      'numblocks' number of blocks into the user's buffer (or until the end of
      the list of blocks, whichever happens first)
          The block coordinates have the same dimensionality (rank) as the
      dataspace they are located within.  The list of blocks is formatted as
      follows: <"start" coordinate> immediately followed by <"opposite" corner
      coordinate>, followed by the next "start" and "opposite" coordinate, etc.
      until all the block information requested has been put into the user's
      buffer.
          No guarantee of any order of the blocks is implied.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_get_select_hyper_blocklist(H5S_t *space, hbool_t internal, hsize_t startblock, hsize_t numblocks, hsize_t *buf)
  {
      herr_t ret_value = SUCCEED; /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      HDassert(space);
      HDassert(buf);
  
      /* Check for a "regular" hyperslab selection */
      if(space->select.sel_info.hslab->diminfo_valid) {
          const H5S_hyper_dim_t *diminfo; /* Alias for dataspace's diminfo information */
          hsize_t tmp_count[H5O_LAYOUT_NDIMS];    /* Temporary hyperslab counts */
          hsize_t offset[H5O_LAYOUT_NDIMS];      /* Offset of element in dataspace */
          unsigned fast_dim;          /* Rank of the fastest changing dimension for the dataspace */
          unsigned ndims;             /* Rank of the dataspace */
          hbool_t done;               /* Whether we are done with the iteration */
          unsigned u;                 /* Counter */
  
          /* Set some convienence values */
          ndims = space->extent.rank;
          fast_dim = ndims - 1;
  
          /* Check which set of dimension information to use */
          if(internal)
              /*
               * Use the "optimized dimension information" to pass back information
               * on the blocks set, not the "application information".
               */
              diminfo = space->select.sel_info.hslab->opt_diminfo;
          else
              /*
               * Use the "application dimension information" to pass back to the user
               * the blocks they set, not the optimized, internal information.
               */
              diminfo = space->select.sel_info.hslab->app_diminfo;
  
          /* Build the tables of count sizes as well as the initial offset */
          for(u = 0; u < ndims; u++) {
              tmp_count[u] = diminfo[u].count;
              offset[u] = diminfo[u].start;
          } /* end for */
  
          /* We're not done with the iteration */
          done = FALSE;
  
          /* Go iterate over the hyperslabs */
          while(!done && numblocks > 0) {
              hsize_t temp_off;           /* Offset in a given dimension */
  
              /* Iterate over the blocks in the fastest dimension */
              while(tmp_count[fast_dim] > 0 && numblocks > 0) {
  
                  /* Check if we should copy this block information */
                  if(startblock == 0) {
                      /* Copy the starting location */
                      HDmemcpy(buf, offset, sizeof(hsize_t) * ndims);
                      buf += ndims;
  
                      /* Compute the ending location */
                      HDmemcpy(buf, offset, sizeof(hsize_t) * ndims);
                      for(u = 0; u < ndims; u++)
                          buf[u] += (diminfo[u].block - 1);
                      buf += ndims;
  
                      /* Decrement the number of blocks to retrieve */
                      numblocks--;
                  } /* end if */
                  else
                      startblock--;
  
                  /* Move the offset to the next sequence to start */
                  offset[fast_dim] += diminfo[fast_dim].stride;
  
                  /* Decrement the block count */
                  tmp_count[fast_dim]--;
              } /* end while */
  
              /* Work on other dimensions if necessary */
              if(fast_dim > 0 && numblocks > 0) {
                  int temp_dim;               /* Temporary rank holder */
  
                  /* Reset the block counts */
                  tmp_count[fast_dim] = diminfo[fast_dim].count;
  
                  /* Bubble up the decrement to the slower changing dimensions */
                  temp_dim = (int)(fast_dim - 1);
                  while(temp_dim >= 0 && !done) {
                      /* Decrement the block count */
                      tmp_count[temp_dim]--;
  
                      /* Check if we have more blocks left */
                      if(tmp_count[temp_dim] > 0)
                          break;
  
                      /* Check for getting out of iterator */
                      if(temp_dim == 0)
                          done = TRUE;
  
                      /* Reset the block count in this dimension */
                      tmp_count[temp_dim] = diminfo[temp_dim].count;
  
                      /* Wrapped a dimension, go up to next dimension */
                      temp_dim--;
                  } /* end while */
              } /* end if */
  
              /* Re-compute offset array */
              for(u = 0; u < ndims; u++) {
                  temp_off = diminfo[u].start + diminfo[u].stride * (diminfo[u].count - tmp_count[u]);
                  offset[u] = temp_off;
              } /* end for */
          } /* end while */
      } /* end if */
      else {
          hsize_t start[H5O_LAYOUT_NDIMS];   /* Location of start of hyperslab */
          hsize_t end[H5O_LAYOUT_NDIMS];     /* Location of end of hyperslab */
  
          ret_value = H5S_hyper_span_blocklist(space->select.sel_info.hslab->span_lst, start, end, (hsize_t)0, &startblock, &numblocks, &buf);
      } /* end else */
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_get_select_hyper_blocklist() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5Sget_select_hyper_blocklist
   PURPOSE
      Get the list of hyperslab blocks currently selected
   USAGE
      herr_t H5Sget_select_hyper_blocklist(dsid, startblock, numblocks, buf)
          hid_t dsid;             IN: Dataspace ID of selection to query
          hsize_t startblock;     IN: Hyperslab block to start with
          hsize_t numblocks;      IN: Number of hyperslab blocks to get
          hsize_t buf[];          OUT: List of hyperslab blocks selected
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
          Puts a list of the hyperslab blocks into the user's buffer.  The blocks
      start with the 'startblock'th block in the list of blocks and put
      'numblocks' number of blocks into the user's buffer (or until the end of
      the list of blocks, whichever happen first)
          The block coordinates have the same dimensionality (rank) as the
      dataspace they are located within.  The list of blocks is formatted as
      follows: <"start" coordinate> immediately followed by <"opposite" corner
      coordinate>, followed by the next "start" and "opposite" coordinate, etc.
      until all the block information requested has been put into the user's
      buffer.
          No guarantee of any order of the blocks is implied.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  herr_t
  H5Sget_select_hyper_blocklist(hid_t spaceid, hsize_t startblock,
      hsize_t numblocks, hsize_t buf[/*numblocks*/])
  {
      H5S_t *space;               /* Dataspace to modify selection of */
      herr_t ret_value;           /* return value */
  
      FUNC_ENTER_API(FAIL)
      H5TRACE4("e", "ihh*[a2]h", spaceid, startblock, numblocks, buf);
  
      /* Check args */
      if(buf == NULL)
          HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid pointer")
      if(NULL == (space = (H5S_t *)H5I_object_verify(spaceid, H5I_DATASPACE)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space")
      if(H5S_GET_SELECT_TYPE(space)!=H5S_SEL_HYPERSLABS)
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a hyperslab selection")
  
      /* Go get the correct number of blocks */
      if(numblocks > 0)
          ret_value = H5S_get_select_hyper_blocklist(space, 0, startblock, numblocks, buf);
      else
          ret_value=SUCCEED;      /* Successfully got 0 blocks... */
  
  done:
      FUNC_LEAVE_API(ret_value)
  }   /* H5Sget_select_hyper_blocklist() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_bounds_helper
   PURPOSE
      Gets the bounding box containing the selection.
   USAGE
      htri_t H5S_hyper_bounds_helper(spans, offset, rank);
          const H5S_hyper_span_info_t *spans; IN: Pointer to current hyperslab span tree
          const hssize_t *offset;         IN: Pointer to offset array
          hsize_t rank;                   IN: Current rank looking at
          hsize_t *start;                 OUT: Start array bounds
          hsize_t *end;                   OUT: End array bounds
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Retrieves the bounding box containing the current selection and places
      it into the user's buffers.  The start and end buffers must be large
      enough to hold the dataspace rank number of coordinates.  The bounding box
      exactly contains the selection, ie. if a 2-D element selection is currently
      defined with the following points: (4,5), (6,8) (10,7), the bounding box
      with be (4, 5), (10, 8).
          The bounding box calculations _does_ include the current offset of the
      selection within the dataspace extent.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_bounds_helper(const H5S_hyper_span_info_t *spans, const hssize_t *offset, hsize_t rank, hsize_t *start, hsize_t *end)
  {
      H5S_hyper_span_t *curr;             /* Hyperslab information nodes */
      herr_t      ret_value = SUCCEED;    /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(spans);
      HDassert(offset);
      HDassert(rank < H5O_LAYOUT_NDIMS);
      HDassert(start);
      HDassert(end);
  
      /* Check each point to determine whether selection+offset is within extent */
      curr=spans->head;
      while(curr!=NULL) {
          /* Check for offset moving selection negative */
          if(((hssize_t)curr->low + offset[rank]) < 0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "offset moves selection out of bounds")
  
          /* Check if the current span extends the bounding box */
          if((curr->low + (hsize_t)offset[rank]) < start[rank])
              start[rank] = curr->low + (hsize_t)offset[rank];
          if((curr->high + (hsize_t)offset[rank]) > end[rank])
              end[rank] = curr->high + (hsize_t)offset[rank];
  
          /* Recurse if this node has down spans */
          if(curr->down != NULL) {
              if(H5S_hyper_bounds_helper(curr->down, offset, (rank + 1), start, end) < 0)
                  HGOTO_ERROR(H5E_DATASPACE, H5E_BADSELECT, FAIL, "failure in lower dimension")
          } /* end if */
  
          /* Advance to next node */
          curr = curr->next;
      } /* end while */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  } /* end H5S_hyper_bounds_helper() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_bounds
   PURPOSE
      Gets the bounding box containing the selection.
   USAGE
      herr_t H5S_hyper_bounds(space, hsize_t *start, hsize_t *end)
          H5S_t *space;           IN: Dataspace pointer of selection to query
          hsize_t *start;         OUT: Starting coordinate of bounding box
          hsize_t *end;           OUT: Opposite coordinate of bounding box
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Retrieves the bounding box containing the current selection and places
      it into the user's buffers.  The start and end buffers must be large
      enough to hold the dataspace rank number of coordinates.  The bounding box
      exactly contains the selection, ie. if a 2-D element selection is currently
      defined with the following points: (4,5), (6,8) (10,7), the bounding box
      with be (4, 5), (10, 8).
          The bounding box calculations _does_ include the current offset of the
      selection within the dataspace extent.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_bounds(const H5S_t *space, hsize_t *start, hsize_t *end)
  {
      unsigned rank;              /* Dataspace rank */
      unsigned i;                 /* index variable */
      herr_t ret_value = SUCCEED; /* Return value */
  
      FUNC_ENTER_NOAPI(FAIL)
  
      HDassert(space);
      HDassert(start);
      HDassert(end);
  
      /* Set the start and end arrays up */
      rank = space->extent.rank;
      for(i = 0; i < rank; i++) {
          start[i] = HSIZET_MAX;
          end[i] = 0;
      } /* end for */
  
      /* Check for a "regular" hyperslab selection */
      if(space->select.sel_info.hslab->diminfo_valid) {
          const H5S_hyper_dim_t *diminfo = space->select.sel_info.hslab->opt_diminfo; /* local alias for diminfo */
  
          /* Check each dimension */
          for(i = 0; i < rank; i++) {
              /* Check for offset moving selection negative */
              if((space->select.offset[i] + (hssize_t)diminfo[i].start) < 0)
                  HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "offset moves selection out of bounds")
  
              /* Compute the smallest location in this dimension */
              start[i] = diminfo[i].start + (hsize_t)space->select.offset[i];
  
              /* Compute the largest location in this dimension */
              end[i] = diminfo[i].start + diminfo[i].stride * (diminfo[i].count - 1) + (diminfo[i].block - 1) + (hsize_t)space->select.offset[i];
          } /* end for */
      } /* end if */
      else {
          /* Call the recursive routine to get the bounds for the span tree */
          ret_value = H5S_hyper_bounds_helper(space->select.sel_info.hslab->span_lst, space->select.offset, (hsize_t)0, start, end);
      } /* end if */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_bounds() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_offset
   PURPOSE
      Gets the linear offset of the first element for the selection.
   USAGE
      herr_t H5S_hyper_offset(space, offset)
          const H5S_t *space;     IN: Dataspace pointer of selection to query
          hsize_t *offset;        OUT: Linear offset of first element in selection
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Retrieves the linear offset (in "units" of elements) of the first element
      selected within the dataspace.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
      Calling this function on a "none" selection returns fail.
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_offset(const H5S_t *space, hsize_t *offset)
  {
      const hssize_t *sel_offset; /* Pointer to the selection's offset */
      const hsize_t *dim_size;    /* Pointer to a dataspace's extent */
      hsize_t accum;              /* Accumulator for dimension sizes */
      unsigned rank;              /* Dataspace rank */
      int i;                      /* index variable */
      herr_t ret_value = SUCCEED; /* Return value */
  
      FUNC_ENTER_NOAPI(FAIL)
  
      HDassert(space && space->extent.rank>0);
      HDassert(offset);
  
      /* Start at linear offset 0 */
      *offset = 0;
  
      /* Set up pointers to arrays of values */
      rank = space->extent.rank;
      sel_offset = space->select.offset;
      dim_size = space->extent.size;
  
      /* Check for a "regular" hyperslab selection */
      if(space->select.sel_info.hslab->diminfo_valid) {
          const H5S_hyper_dim_t *diminfo = space->select.sel_info.hslab->opt_diminfo; /* Local alias for diminfo */
  
          /* Loop through starting coordinates, calculating the linear offset */
          accum = 1;
          for(i = (int)(rank - 1); i >= 0; i--) {
              hssize_t hyp_offset = (hssize_t)diminfo[i].start + sel_offset[i]; /* Hyperslab's offset in this dimension */
  
              /* Check for offset moving selection out of the dataspace */
              if(hyp_offset < 0 || (hsize_t)hyp_offset >= dim_size[i])
                  HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "offset moves selection out of bounds")
  
              /* Add the hyperslab's offset in this dimension to the total linear offset */
              *offset += (hsize_t)(hyp_offset * (hssize_t)accum);
  
              /* Increase the accumulator */
              accum *= dim_size[i];
          } /* end for */
      } /* end if */
      else {
          const H5S_hyper_span_t *span;           /* Hyperslab span node */
          hsize_t dim_accum[H5S_MAX_RANK];        /* Accumulators, for each dimension */
  
          /* Calculate the accumulator for each dimension */
          accum = 1;
          for(i = (int)(rank - 1); i >= 0; i--) {
              /* Set the accumulator for this dimension */
              dim_accum[i] = accum;
  
              /* Increase the accumulator */
              accum *= dim_size[i];
          } /* end for */
  
          /* Get information for the first span, in the slowest changing dimension */
          span = space->select.sel_info.hslab->span_lst->head;
  
          /* Work down the spans, computing the linear offset */
          i = 0;
          while(span) {
              hssize_t hyp_offset = (hssize_t)span->low + sel_offset[i]; /* Hyperslab's offset in this dimension */
  
              /* Check for offset moving selection out of the dataspace */
              if(hyp_offset < 0 || (hsize_t)hyp_offset >= dim_size[i])
                  HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "offset moves selection out of bounds")
  
              /* Add the hyperslab's offset in this dimension to the total linear offset */
              *offset += (hsize_t)(hyp_offset * (hssize_t)dim_accum[i]);
  
              /* Advance to first span in "down" dimension */
              if(span->down) {
                  HDassert(span->down->head);
                  span = span->down->head;
              } /* end if */
              else
                  span = NULL;
              i++;
          } /* end while */
      } /* end else */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_offset() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_is_contiguous
   PURPOSE
      Check if a hyperslab selection is contiguous within the dataspace extent.
   USAGE
      htri_t H5S_hyper_is_contiguous(space)
          H5S_t *space;           IN: Dataspace pointer to check
   RETURNS
      TRUE/FALSE/FAIL
   DESCRIPTION
      Checks to see if the current selection in the dataspace is contiguous.
      This is primarily used for reading the entire selection in one swoop.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static htri_t
  H5S_hyper_is_contiguous(const H5S_t *space)
  {
      unsigned small_contiguous,      /* Flag for small contiguous block */
          large_contiguous;           /* Flag for large contiguous block */
      unsigned u;                     /* index variable */
      htri_t ret_value = FALSE;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOERR
  
      HDassert(space);
  
      /* Check for a "regular" hyperslab selection */
      if(space->select.sel_info.hslab->diminfo_valid) {
          const H5S_hyper_dim_t *diminfo=space->select.sel_info.hslab->opt_diminfo; /* local alias for diminfo */
  
          /*
           * For a regular hyperslab to be contiguous, it must have only one
           * block (i.e. count==1 in all dimensions) and the block size must be
           * the same as the dataspace extent's in all but the slowest changing
           * dimension. (dubbed "large contiguous" block)
           *
           * OR
           *
           * The selection must have only one block (i.e. count==1) in all
           * dimensions and the block size must be 1 in all but the fastest
           * changing dimension. (dubbed "small contiguous" block)
           */
  
          /* Initialize flags */
          large_contiguous=TRUE;	/* assume true and reset if the dimensions don't match */
          small_contiguous=FALSE;	/* assume false initially */
  
          /* Check for a "large contigous" block */
          for(u=0; u<space->extent.rank; u++) {
              if(diminfo[u].count>1) {
                  large_contiguous=FALSE;
                  break;
              } /* end if */
              if(u>0 && diminfo[u].block!=space->extent.size[u]) {
                  large_contiguous=FALSE;
                  break;
              } /* end if */
          } /* end for */
  
          /* If we didn't find a large contiguous block, check for a small one */
          if(large_contiguous==FALSE) {
              small_contiguous=TRUE;
              for(u=0; u<space->extent.rank; u++) {
                  if(diminfo[u].count>1) {
                      small_contiguous=FALSE;
                      break;
                  } /* end if */
                  if(u<(space->extent.rank-1) && diminfo[u].block!=1) {
                      small_contiguous=FALSE;
                      break;
                  } /* end if */
              } /* end for */
          } /* end if */
  
          /* Indicate true if it's either a large or small contiguous block */
          if(large_contiguous || small_contiguous)
              ret_value=TRUE;
      } /* end if */
      else {
          H5S_hyper_span_info_t *spans;   /* Hyperslab span info node */
          H5S_hyper_span_t *span;         /* Hyperslab span node */
  
          /*
           * For a hyperslab to be contiguous, it must have only one block and
           * (either it's size must be the same as the dataspace extent's in all
           * but the slowest changing dimension
           * OR
           * block size must be 1 in all but the fastest changing dimension).
           */
          /* Initialize flags */
          large_contiguous=TRUE;	/* assume true and reset if the dimensions don't match */
          small_contiguous=FALSE;	/* assume false initially */
  
          /* Get information for slowest changing information */
          spans=space->select.sel_info.hslab->span_lst;
          span=spans->head;
  
          /* If there are multiple spans in the slowest changing dimension, the selection isn't contiguous */
          if(span->next!=NULL)
              large_contiguous=FALSE;
          else {
              /* Now check the rest of the dimensions */
              if(span->down!=NULL) {
                  u=1;    /* Current dimension working on */
  
                  /* Get the span information for the next fastest dimension */
                  spans=span->down;
  
                  /* Cycle down the spans until we run out of down spans or find a non-contiguous span */
                  while(spans!=NULL) {
                      span=spans->head;
  
                      /* Check that this is the only span and it spans the entire dimension */
                      if(span->next!=NULL) {
                          large_contiguous=FALSE;
                          break;
                      } /* end if */
                      else {
                          /* If this span doesn't cover the entire dimension, then this selection isn't contiguous */
                          if(((span->high-span->low)+1)!=space->extent.size[u]) {
                              large_contiguous=FALSE;
                              break;
                          } /* end if */
                          else {
                              /* Walk down to the next span */
                              spans=span->down;
  
                              /* Increment dimension */
                              u++;
                          } /* end else */
                      } /* end else */
                  } /* end while */
              } /* end if */
          } /* end else */
  
          /* If we didn't find a large contiguous block, check for a small one */
          if(large_contiguous==FALSE) {
              small_contiguous=TRUE;
  
              /* Get information for slowest changing information */
              spans=space->select.sel_info.hslab->span_lst;
              span=spans->head;
  
              /* Current dimension working on */
              u=0;
  
              /* Cycle down the spans until we run out of down spans or find a non-contiguous span */
              while(spans!=NULL) {
                  span=spans->head;
  
                  /* Check that this is the only span and it spans the entire dimension */
                  if(span->next!=NULL) {
                      small_contiguous=FALSE;
                      break;
                  } /* end if */
                  else {
                      /* If this span doesn't cover the entire dimension, then this selection isn't contiguous */
                      if(u<(space->extent.rank-1) && ((span->high-span->low)+1)!=1) {
                          small_contiguous=FALSE;
                          break;
                      } /* end if */
                      else {
                          /* Walk down to the next span */
                          spans=span->down;
  
                          /* Increment dimension */
                          u++;
                      } /* end else */
                  } /* end else */
              } /* end while */
          } /* end if */
  
          /* Indicate true if it's either a large or small contiguous block */
          if(large_contiguous || small_contiguous)
              ret_value=TRUE;
      } /* end else */
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_is_contiguous() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_is_single
   PURPOSE
      Check if a hyperslab selection is a single block within the dataspace extent.
   USAGE
      htri_t H5S_hyper_is_single(space)
          H5S_t *space;           IN: Dataspace pointer to check
   RETURNS
      TRUE/FALSE/FAIL
   DESCRIPTION
      Checks to see if the current selection in the dataspace is a single block.
      This is primarily used for reading the entire selection in one swoop.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static htri_t
  H5S_hyper_is_single(const H5S_t *space)
  {
      H5S_hyper_span_info_t *spans;   /* Hyperslab span info node */
      H5S_hyper_span_t *span;         /* Hyperslab span node */
      unsigned u;                     /* index variable */
      htri_t ret_value=TRUE;         /* return value */
  
      FUNC_ENTER_NOAPI_NOERR
  
      HDassert(space);
  
      /* Check for a "single" hyperslab selection */
      if(space->select.sel_info.hslab->diminfo_valid) {
          /*
           * For a regular hyperslab to be single, it must have only one
           * block (i.e. count==1 in all dimensions)
           */
  
          /* Check for a single block */
          for(u=0; u<space->extent.rank; u++) {
              if(space->select.sel_info.hslab->opt_diminfo[u].count>1)
                  HGOTO_DONE(FALSE)
          } /* end for */
      } /* end if */
      else {
          /*
           * For a region to be single, it must have only one block
           */
          /* Get information for slowest changing information */
          spans=space->select.sel_info.hslab->span_lst;
  
          /* Cycle down the spans until we run out of down spans or find a non-contiguous span */
          while(spans!=NULL) {
              span=spans->head;
  
              /* Check that this is the only span and it spans the entire dimension */
              if(span->next!=NULL)
                  HGOTO_DONE(FALSE)
              else
                  /* Walk down to the next span */
                  spans=span->down;
          } /* end while */
      } /* end else */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_is_single() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_is_regular
   PURPOSE
      Check if a hyperslab selection is "regular"
   USAGE
      htri_t H5S_hyper_is_regular(space)
          const H5S_t *space;     IN: Dataspace pointer to check
   RETURNS
      TRUE/FALSE/FAIL
   DESCRIPTION
      Checks to see if the current selection in a dataspace is the a regular
      pattern.
      This is primarily used for reading the entire selection in one swoop.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
      Doesn't check for "regular" hyperslab selections composed of spans
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static htri_t
  H5S_hyper_is_regular(const H5S_t *space)
  {
      htri_t ret_value;  /* return value */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(space);
  
      /* Only simple check for regular hyperslabs for now... */
      if(space->select.sel_info.hslab->diminfo_valid)
          ret_value=TRUE;
      else
          ret_value=FALSE;
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_is_regular() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_release
   PURPOSE
      Release hyperslab selection information for a dataspace
   USAGE
      herr_t H5S_hyper_release(space)
          H5S_t *space;       IN: Pointer to dataspace
   RETURNS
      Non-negative on success/Negative on failure
   DESCRIPTION
      Releases all hyperslab selection information for a dataspace
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
   * 	Robb Matzke, 1998-08-25
   *	The fields which are freed are set to NULL to prevent them from being
   *	freed again later.  This fixes some allocation problems where
   *	changing the hyperslab selection of one data space causes a core dump
   *	when closing some other data space.
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_release(H5S_t *space)
  {
      herr_t ret_value = SUCCEED;
  
      FUNC_ENTER_NOAPI(FAIL)
  
      /* Check args */
      HDassert(space && H5S_SEL_HYPERSLABS == H5S_GET_SELECT_TYPE(space));
  
      /* Reset the number of points selected */
      space->select.num_elem = 0;
  
      /* Release irregular hyperslab information */
      if(space->select.sel_info.hslab->span_lst != NULL) {
          if(H5S_hyper_free_span_info(space->select.sel_info.hslab->span_lst) < 0)
              HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release hyperslab spans")
      } /* end if */
  
      /* Release space for the hyperslab selection information */
      space->select.sel_info.hslab = H5FL_FREE(H5S_hyper_sel_t, space->select.sel_info.hslab);
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_release() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_recover_span
   PURPOSE
      Recover a generated span, if appropriate
   USAGE
      herr_t H5S_hyper_recover_span(recover, curr_span, next_span)
          unsigned *recover;                 IN/OUT: Pointer recover flag
          H5S_hyper_span_t **curr_span;   IN/OUT: Pointer to current span in list
          H5S_hyper_span_t *next_span;    IN: Pointer to next span
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Check if the current span needs to be recovered and free it if so.
      Set the current span to the next span in any case.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_recover_span (unsigned *recover, H5S_hyper_span_t **curr_span, H5S_hyper_span_t *next_span)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      HDassert(recover);
      HDassert(curr_span);
  
      /* Check if the span should be recovered */
      if(*recover) {
          H5S_hyper_free_span(*curr_span);
          *recover=0;
      } /* end if */
  
      /* Set the current span to next span */
      *curr_span=next_span;
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_recover_span() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_coord_to_span
   PURPOSE
      Create a span tree for a single element
   USAGE
      H5S_hyper_span_t *H5S_hyper_coord_to_span(rank, coords)
          unsigned rank;                  IN: Number of dimensions of coordinate
          hsize_t *coords;               IN: Location of element
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Create a span tree for a single element
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static H5S_hyper_span_t *
  H5S_hyper_coord_to_span(unsigned rank, hsize_t *coords)
  {
      H5S_hyper_span_t *new_span;         /* Pointer to new span tree for coordinate */
      H5S_hyper_span_info_t *down=NULL;   /* Pointer to new span tree for next level down */
      H5S_hyper_span_t *ret_value=NULL;   /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(rank > 0);
      HDassert(coords);
  
      /* Search for location to insert new element in tree */
      if(rank>1) {
          /* Allocate a span info node */
          if((down = H5FL_MALLOC(H5S_hyper_span_info_t))==NULL)
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
          /* Set the reference count */
          down->count=0;
  
          /* Reset the scratch pad space */
          down->scratch=0;
  
          /* Build span tree for coordinates below this one */
          if((down->head=H5S_hyper_coord_to_span(rank-1,&coords[1]))==NULL)
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
      } /* end if */
  
      /* Build span for this coordinate */
      if((new_span = H5S_hyper_new_span(coords[0],coords[0],down,NULL))==NULL)
          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
      /* Set return value */
      ret_value=new_span;
  
  done:
      if(ret_value==NULL) {
          if(down!=NULL)
              H5S_hyper_free_span_info(down);
      } /* end if */
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_coord_to_span() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_add_span_element_helper
   PURPOSE
      Add a single elment to a span tree
   USAGE
      herr_t H5S_hyper_add_span_element_helper(prev_span, span_tree, rank, coords)
          H5S_hyper_span_info_t *span_tree;  IN/OUT: Pointer to span tree to append to
          unsigned rank;                  IN: Number of dimensions of coordinates
          hsize_t *coords;               IN: Location of element to add to span tree
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Add a single element to an existing span tree.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
      Assumes that the element is not already covered by the span tree
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_add_span_element_helper(H5S_hyper_span_info_t *span_tree, unsigned rank, hsize_t *coords)
  {
      H5S_hyper_span_info_t *tspan_info;  /* Temporary pointer to span info */
      H5S_hyper_span_info_t *prev_span_info;  /* Pointer to span info for level above current position */
      H5S_hyper_span_t *tmp_span;         /* Temporary pointer to a span */
      H5S_hyper_span_t *tmp2_span;        /* Another temporary pointer to a span */
      H5S_hyper_span_t *new_span;         /* New span created for element */
      herr_t ret_value=SUCCEED;           /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(span_tree);
      HDassert(rank > 0);
      HDassert(coords);
  
      /* Get pointer to last span in span tree */
      tspan_info=span_tree;
      if(span_tree->scratch)
          tmp_span=(H5S_hyper_span_t *)span_tree->scratch;
      else {
          tmp_span=span_tree->head;
          HDassert(tmp_span);
          span_tree->scratch=(H5S_hyper_span_info_t *)tmp_span;
      } /* end else */
  
      /* Find last span tree which includes a portion of the coordinate */
      prev_span_info=NULL;
      while(coords[0]>=tmp_span->low && coords[0]<=tmp_span->high) {
          /* Move rank & coordinate offset down a dimension */
          rank--;
          coords++;
  
          /* Remember the span tree we are descending into */
          prev_span_info=tspan_info;
          tspan_info=tmp_span->down;
  
          /* Get the last span in this span's 'down' tree */
          if(tspan_info->scratch)
              tmp_span=(H5S_hyper_span_t *)tspan_info->scratch;
          else {
              tmp_span=tspan_info->head;
              HDassert(tmp_span);
              tspan_info->scratch=(H5S_hyper_span_info_t *)tmp_span;
          } /* end else */
      } /* end while */
  
      /* Check if we made it all the way to the bottom span in the tree */
      if(rank>1) {
          /* Before we create another span at this level in the tree, check if
           * the last span's "down tree" was equal to any other spans in this
           * list of spans in the span tree.
           *
           * If so, release last span information and make last span merge into
           * previous span (if possible), or at least share their "down tree"
           * information.
           */
          tmp2_span=tspan_info->head;
          while(tmp2_span!=tmp_span) {
              if(H5S_hyper_cmp_spans(tmp2_span->down,tmp_span->down)==TRUE) {
                  /* Check for merging into previous span */
                  if(tmp2_span->high+1==tmp_span->low) {
                      /* Release last span created */
                      H5S_hyper_free_span(tmp_span);
  
                      /* Increase size of previous span */
                      tmp2_span->high++;
                      tmp2_span->nelem++;
  
                      /* Reset the 'tmp_span' for the rest of this block's algorithm */
                      tmp_span=tmp2_span;
                  } /* end if */
                  /* Span is disjoint, but has the same "down tree" selection */
                  else {
                      /* Release "down tree" information */
                      H5S_hyper_free_span_info(tmp_span->down);
  
                      /* Point at earlier span's "down tree" */
                      tmp_span->down=tmp2_span->down;
  
                      /* Increment reference count on shared "down tree" */
                      tmp_span->down->count++;
                  } /* end else */
  
                  /* Found span to merge into, break out now */
                  break;
              } /* end if */
  
              /* Advance to next span to check */
              tmp2_span=tmp2_span->next;
          } /* end while */
  
          /* Make span tree for current coordinates */
          if((new_span=H5S_hyper_coord_to_span(rank,coords))==NULL)
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
          /* Add new span tree as span */
          HDassert(tmp_span);
          tmp_span->next=new_span;
  
          /* Make scratch pointer point to last span in list */
          HDassert(tspan_info);
          tspan_info->scratch=(H5S_hyper_span_info_t *)new_span;
  
          /* Set the proper 'pstride' for new span */
          new_span->pstride=new_span->low-tmp_span->low;
      } /* end if */
      else {
          /* Does new node adjoin existing node? */
          if(tmp_span->high+1==coords[0]) {
              tmp_span->high++;
              tmp_span->nelem++;
  
              /* Check if this span tree should now be merged with a level higher in the tree */
              if(prev_span_info!=NULL) {
                  /* Before we create another span at this level in the tree, check if
                   * the last span's "down tree" was equal to any other spans in this
                   * list of spans in the span tree.
                   *
                   * If so, release last span information and make last span merge into
                   * previous span (if possible), or at least share their "down tree"
                   * information.
                   */
                  tmp2_span=prev_span_info->head;
                  tmp_span=(H5S_hyper_span_t *)prev_span_info->scratch;
                  while(tmp2_span!=tmp_span) {
                      if(H5S_hyper_cmp_spans(tmp2_span->down,tmp_span->down)==TRUE) {
                          /* Check for merging into previous span */
                          if(tmp2_span->high+1==tmp_span->low) {
                              /* Release last span created */
                              H5S_hyper_free_span(tmp_span);
  
                              /* Increase size of previous span */
                              tmp2_span->high++;
                              tmp2_span->nelem++;
  
                              /* Update pointers */
                              tmp2_span->next=NULL;
                              prev_span_info->scratch=(H5S_hyper_span_info_t *)tmp2_span;
                          } /* end if */
                          /* Span is disjoint, but has the same "down tree" selection */
                          else {
                              /* Release "down tree" information */
                              H5S_hyper_free_span_info(tmp_span->down);
  
                              /* Point at earlier span's "down tree" */
                              tmp_span->down=tmp2_span->down;
  
                              /* Increment reference count on shared "down tree" */
                              tmp_span->down->count++;
                          } /* end else */
  
                          /* Found span to merge into, break out now */
                          break;
                      } /* end if */
  
                      /* Advance to next span to check */
                      tmp2_span=tmp2_span->next;
                  } /* end while */
              } /* end if */
          } /* end if */
          else {
              if((new_span = H5S_hyper_new_span(coords[0],coords[0],NULL,NULL))==NULL)
                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
              /* Add new span tree as span */
              HDassert(tmp_span);
              tmp_span->next=new_span;
  
              /* Make scratch pointer point to last span in list */
              tspan_info->scratch=(H5S_hyper_span_info_t *)new_span;
  
              /* Set the proper 'pstride' for new span */
              new_span->pstride=new_span->low-tmp_span->low;
          } /* end else */
      } /* end else */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_add_span_element_helper() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_add_span_element
   PURPOSE
      Add a single elment to a span tree
   USAGE
      herr_t H5S_hyper_add_span_element(space, span_tree, rank, coords)
          H5S_t *space;           IN/OUT: Pointer to dataspace to add coordinate to
          unsigned rank;          IN: Number of dimensions of coordinates
          hsize_t *coords;       IN: Location of element to add to span tree
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Add a single element to an existing span tree.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
      Assumes that the element is not already in the dataspace's selection
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  herr_t
  H5S_hyper_add_span_element(H5S_t *space, unsigned rank, hsize_t *coords)
  {
      H5S_hyper_span_info_t *head = NULL;    /* Pointer to new head of span tree */
      herr_t      ret_value = SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(space);
      HDassert(rank > 0);
      HDassert(coords);
  
      /* Check if this is the first element in the selection */
      if(NULL == space->select.sel_info.hslab) {
          /* Allocate a span info node */
          if(NULL == (head = H5FL_MALLOC(H5S_hyper_span_info_t)))
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
          /* Set the reference count */
          head->count = 1;
  
          /* Reset the scratch pad space */
          head->scratch = 0;
  
          /* Build span tree for this coordinate */
          if(NULL == (head->head = H5S_hyper_coord_to_span(rank, coords)))
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
          /* Allocate selection info */
          if(NULL == (space->select.sel_info.hslab = H5FL_MALLOC(H5S_hyper_sel_t)))
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab info")
  
          /* Set the selection to the new span tree */
          space->select.sel_info.hslab->span_lst = head;
  
          /* Set selection type */
          space->select.type = H5S_sel_hyper;
  
          /* Reset "regular" hyperslab flag */
          space->select.sel_info.hslab->diminfo_valid = FALSE;
  
          /* Set # of elements in selection */
          space->select.num_elem = 1;
      } /* end if */
      else {
          if(H5S_hyper_add_span_element_helper(space->select.sel_info.hslab->span_lst, rank, coords) < 0)
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
          /* Increment # of elements in selection */
          space->select.num_elem++;
      } /* end else */
  
  done:
      if(ret_value < 0)
          if(head)
              H5S_hyper_free_span_info(head);
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_add_span_element() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_reset_scratch
   PURPOSE
      Reset the scratch information for span tree
   USAGE
      herr_t H5S_hyper_reset_scratch(space)
          H5S_t *space;           IN/OUT: Pointer to dataspace to reset scratch pointers
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Resets the "scratch" pointers used for various tasks in computing hyperslab
      spans.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  herr_t
  H5S_hyper_reset_scratch(H5S_t *space)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      HDassert(space);
  
      /* Check if there are spans in the span tree */
      if(space->select.sel_info.hslab->span_lst != NULL)
          /* Reset the scratch pointers for the next routine which needs them */
          H5S_hyper_span_scratch(space->select.sel_info.hslab->span_lst, NULL);
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_reset_scratch() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_convert
   PURPOSE
      Convert a compatible selection to span tree form
   USAGE
      herr_t H5S_hyper_convert(space)
          H5S_t *space;           IN/OUT: Pointer to dataspace to convert
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Converts a compatible selection (currently only "all" selections) to the
      span-tree form of a hyperslab selection. (Point and "none" selection aren't
      currently supported and hyperslab selection always have the span-tree form
      available).
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  herr_t
  H5S_hyper_convert(H5S_t *space)
  {
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(space);
  
      /* Check the type of selection */
      switch(H5S_GET_SELECT_TYPE(space)) {
          case H5S_SEL_ALL:    /* All elements selected in dataspace */
              /* Convert current "all" selection to "real" hyperslab selection */
              {
                  hsize_t tmp_start[H5O_LAYOUT_NDIMS];   /* Temporary start information */
                  hsize_t tmp_stride[H5O_LAYOUT_NDIMS];   /* Temporary stride information */
                  hsize_t tmp_count[H5O_LAYOUT_NDIMS];    /* Temporary count information */
                  hsize_t tmp_block[H5O_LAYOUT_NDIMS];    /* Temporary block information */
                  unsigned u;                             /* Local index variable */
  
                  /* Fill in temporary information for the dimensions */
                  for(u=0; u<space->extent.rank; u++) {
                      tmp_start[u]=0;
                      tmp_stride[u]=1;
                      tmp_count[u]=1;
                      tmp_block[u]=space->extent.size[u];
                  } /* end for */
  
                  /* Convert to hyperslab selection */
                  if(H5S_select_hyperslab(space,H5S_SELECT_SET,tmp_start,tmp_stride,tmp_count,tmp_block)<0)
                      HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't convert selection")
              } /* end case */
              break;
  
          case H5S_SEL_HYPERSLABS:        /* Hyperslab selection */
              break;
  
          case H5S_SEL_NONE:   /* No elements selected in dataspace */
          case H5S_SEL_POINTS: /* Point selection */
          case H5S_SEL_ERROR:  /* Selection error */
          case H5S_SEL_N:      /* Selection count */
          default:
              HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "can't convert to span tree selection")
      } /* end switch */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_convert() */
  
  #ifdef LATER
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_intersect_helper
   PURPOSE
      Helper routine to detect intersections in span trees
   USAGE
      htri_t H5S_hyper_intersect_helper(spans1, spans2)
          H5S_hyper_span_info_t *spans1;     IN: First span tree to operate with
          H5S_hyper_span_info_t *spans2;     IN: Second span tree to operate with
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Quickly detect intersections between two span trees
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static htri_t
  H5S_hyper_intersect_helper (H5S_hyper_span_info_t *spans1, H5S_hyper_span_info_t *spans2)
  {
      H5S_hyper_span_t *curr1;    /* Pointer to current span in 1st span tree */
      H5S_hyper_span_t *curr2;    /* Pointer to current span in 2nd span tree */
      htri_t status;              /* Status from recursive call */
      htri_t ret_value=FALSE;     /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Sanity check */
      HDassert((spans1 && spans2) || (spans1 == NULL && spans2 == NULL));
  
      /* "NULL" span trees compare as overlapping */
      if(spans1==NULL && spans2==NULL)
          HGOTO_DONE(TRUE);
  
      /* Get the span lists for each span in this tree */
      curr1=spans1->head;
      curr2=spans2->head;
  
      /* Iterate over the spans in each tree */
      while(curr1!=NULL && curr2!=NULL) {
          /* Check for 1st span entirely before 2nd span */
          if(curr1->high<curr2->low)
              curr1=curr1->next;
          /* Check for 2nd span entirely before 1st span */
          else if(curr2->high<curr1->low)
              curr2=curr2->next;
          /* Spans must overlap */
          else {
              /* Recursively check spans in next dimension down */
              if((status=H5S_hyper_intersect_helper(curr1->down,curr2->down))<0)
                  HGOTO_ERROR(H5E_DATASPACE, H5E_BADSELECT, FAIL, "can't perform hyperslab intersection check")
  
              /* If there is a span intersection in the down dimensions, the span trees overlap */
              if(status==TRUE)
                  HGOTO_DONE(TRUE);
  
              /* No intersection in down dimensions, advance to next span */
              if(curr1->high<curr2->high)
                  curr1=curr1->next;
              else
                  curr2=curr2->next;
          } /* end else */
      } /* end while */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_intersect_helper() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_intersect
   PURPOSE
      Detect intersections in span trees
   USAGE
      htri_t H5S_hyper_intersect(space1, space2)
          H5S_t *space1;     IN: First dataspace to operate on span tree
          H5S_t *space2;     IN: Second dataspace to operate on span tree
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Quickly detect intersections between two span trees
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  htri_t
  H5S_hyper_intersect (H5S_t *space1, H5S_t *space2)
  {
      htri_t ret_value=FAIL;      /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Sanity check */
      HDassert(space1);
      HDassert(space2);
  
      /* Check that the space selections both have span trees */
      if(space1->select.sel_info.hslab->span_lst==NULL ||
              space2->select.sel_info.hslab->span_lst==NULL)
          HGOTO_ERROR(H5E_DATASPACE, H5E_UNINITIALIZED, FAIL, "dataspace does not have span tree")
  
      /* Check that the dataspaces are both the same rank */
      if(space1->extent.rank!=space2->extent.rank)
          HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "dataspace ranks don't match")
  
      /* Perform the span-by-span intersection check */
      if((ret_value=H5S_hyper_intersect_helper(space1->select.sel_info.hslab->span_lst,space2->select.sel_info.hslab->span_lst))<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_BADSELECT, FAIL, "can't perform hyperslab intersection check")
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_intersect() */
  #endif /* LATER */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_intersect_block_helper
   PURPOSE
      Helper routine to detect intersections in span trees
   USAGE
      htri_t H5S_hyper_intersect_block_helper(spans, start, end)
          H5S_hyper_span_info_t *spans;     IN: First span tree to operate with
          hssize_t *offset;   IN: Selection offset coordinate
          hsize_t *start;    IN: Starting coordinate for block
          hsize_t *end;      IN: Ending coordinate for block
   RETURN
      Non-negative on success, negative on failure
   DESCRIPTION
      Quickly detect intersections between span tree and block
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static htri_t
  H5S_hyper_intersect_block_helper (const H5S_hyper_span_info_t *spans, hsize_t *start, hsize_t *end)
  {
      H5S_hyper_span_t *curr;     /* Pointer to current span in 1st span tree */
      htri_t status;              /* Status from recursive call */
      htri_t ret_value=FALSE;     /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Sanity check */
      HDassert(spans);
      HDassert(start);
      HDassert(end);
  
      /* Get the span list for spans in this tree */
      curr=spans->head;
  
      /* Iterate over the spans in the tree */
      while(curr!=NULL) {
          /* Check for span entirely before block */
          if(curr->high < *start)
              /* Advance to next span in this dimension */
              curr=curr->next;
          /* If this span is past the end of the block, then we're done in this dimension */
          else if(curr->low > *end)
              HGOTO_DONE(FALSE)
          /* block & span overlap */
          else {
              if(curr->down==NULL)
                  HGOTO_DONE(TRUE)
              else {
                  /* Recursively check spans in next dimension down */
                  if((status=H5S_hyper_intersect_block_helper(curr->down,start+1,end+1))<0)
                      HGOTO_ERROR(H5E_DATASPACE, H5E_BADSELECT, FAIL, "can't perform hyperslab intersection check")
  
                  /* If there is a span intersection in the down dimensions, the span trees overlap */
                  if(status==TRUE)
                      HGOTO_DONE(TRUE);
  
                  /* No intersection in down dimensions, advance to next span */
                  curr=curr->next;
              } /* end else */
          } /* end else */
      } /* end while */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_intersect_block_helper() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_intersect_block
   PURPOSE
      Detect intersections in span trees
   USAGE
      htri_t H5S_hyper_intersect_block(space, start, end)
          H5S_t *space;       IN: First dataspace to operate on span tree
          hssize_t *start;    IN: Starting coordinate for block
          hssize_t *end;      IN: Ending coordinate for block
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Quickly detect intersections between span tree and block
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  htri_t
  H5S_hyper_intersect_block (H5S_t *space, hsize_t *start, hsize_t *end)
  {
      htri_t ret_value=FAIL;      /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Sanity check */
      HDassert(space);
      HDassert(start);
      HDassert(end);
  
      /* Check for 'all' selection, instead of a hyperslab selection */
      /* (Technically, this shouldn't be in the "hyperslab" routines...) */
      if(H5S_GET_SELECT_TYPE(space)==H5S_SEL_ALL)
          HGOTO_DONE(TRUE);
  
      /* Check that the space selection has a span tree */
      if(space->select.sel_info.hslab->span_lst==NULL)
          if(H5S_hyper_generate_spans(space)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_UNINITIALIZED, FAIL, "dataspace does not have span tree")
  
      /* Perform the span-by-span intersection check */
      if((ret_value=H5S_hyper_intersect_block_helper(space->select.sel_info.hslab->span_lst,start,end))<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_BADSELECT, FAIL, "can't perform hyperslab intersection check")
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_intersect_block() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_adjust_helper_u
   PURPOSE
      Helper routine to adjust offsets in span trees
   USAGE
      herr_t H5S_hyper_adjust_helper_u(spans, offset)
          H5S_hyper_span_info_t *spans;   IN: Span tree to operate with
          const hsize_t *offset;         IN: Offset to subtract
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Adjust the location of the spans in a span tree by subtracting an offset
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_adjust_helper_u (H5S_hyper_span_info_t *spans, const hsize_t *offset)
  {
      H5S_hyper_span_t *span;     /* Pointer to current span in span tree */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Sanity check */
      HDassert(spans);
      HDassert(offset);
  
      /* Check if we've already set this down span tree */
      if(spans->scratch!=(H5S_hyper_span_info_t *)~((size_t)NULL)) {
          /* Set the tree's scratch pointer */
          spans->scratch=(H5S_hyper_span_info_t *)~((size_t)NULL);
  
          /* Get the span lists for each span in this tree */
          span=spans->head;
  
          /* Iterate over the spans in tree */
          while(span!=NULL) {
              /* Adjust span offset */
              HDassert(span->low>=*offset);
              span->low-=*offset;
              span->high-=*offset;
  
              /* Recursively adjust spans in next dimension down */
              if(span->down!=NULL)
                  H5S_hyper_adjust_helper_u(span->down,offset+1);
  
              /* Advance to next span in this dimension */
              span=span->next;
          } /* end while */
      } /* end if */
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_adjust_helper_u() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_adjust_u
   PURPOSE
      Adjust a hyperslab selection by subtracting an offset
   USAGE
      herr_t H5S_hyper_adjust_u(space,offset)
          H5S_t *space;           IN/OUT: Pointer to dataspace to adjust
          const hsize_t *offset; IN: Offset to subtract
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Moves a hyperslab selection by subtracting an offset from it.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_adjust_u(H5S_t *space, const hsize_t *offset)
  {
      unsigned u;                         /* Local index variable */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(space);
      HDassert(offset);
  
      /* Subtract the offset from the "regular" coordinates, if they exist */
      if(space->select.sel_info.hslab->diminfo_valid) {
          for(u=0; u<space->extent.rank; u++) {
              HDassert(space->select.sel_info.hslab->opt_diminfo[u].start>=offset[u]);
              space->select.sel_info.hslab->opt_diminfo[u].start-=offset[u];
          } /* end for */
      } /* end if */
  
      /* Subtract the offset from the span tree coordinates, if they exist */
      if(space->select.sel_info.hslab->span_lst) {
          if(H5S_hyper_adjust_helper_u(space->select.sel_info.hslab->span_lst,offset)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_BADSELECT, FAIL, "can't perform hyperslab offset adjustment")
  
          /* Reset the scratch pointers for the next routine which needs them */
          H5S_hyper_span_scratch(space->select.sel_info.hslab->span_lst, NULL);
      } /* end if */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_adjust_u() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_hyper_project_scalar
   *
   * Purpose:	Projects a single element hyperslab selection into a scalar
   *              dataspace
   *
   * Return:	non-negative on success, negative on failure.
   *
   * Programmer:	Quincey Koziol
   *              Sunday, July 18, 2010
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_hyper_project_scalar(const H5S_t *space, hsize_t *offset)
  {
      hsize_t block[H5S_MAX_RANK];     /* Block selected in base dataspace */
      herr_t ret_value = SUCCEED;         /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Check args */
      HDassert(space && H5S_SEL_HYPERSLABS == H5S_GET_SELECT_TYPE(space));
      HDassert(offset);
  
      /* Check for a "regular" hyperslab selection */
      if(space->select.sel_info.hslab->diminfo_valid) {
          const H5S_hyper_dim_t *diminfo = space->select.sel_info.hslab->opt_diminfo; /* Alias for dataspace's diminfo information */
          unsigned u;                 /* Counter */
  
          /* Build the table of the initial offset */
          for(u = 0; u < space->extent.rank; u++) {
              block[u] = diminfo[u].start;
  
              /* Check for more than one hyperslab */
              if(diminfo[u].count > 1 || diminfo[u].block > 1)
                  HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "hyperslab selection of one element has more than one node!")
          } /* end for */
      } /* end if */
      else {
          const H5S_hyper_span_t *curr;           /* Pointer to current hyperslab span */
          unsigned curr_dim;                      /* Current dimension being operated on */
  
          /* Advance down selected spans */
          curr = space->select.sel_info.hslab->span_lst->head;
          curr_dim = 0;
          while(curr) {
              /* Check for more than one span */
              if(curr->next || curr->low != curr->high)
                  HGOTO_ERROR(H5E_DATASPACE, H5E_BADRANGE, FAIL, "hyperslab selection of one element has more than one node!")
  
              /* Save the location of the selection in current dimension */
              block[curr_dim] = curr->low;
  
              /* Advance down to next dimension */
              curr = curr->down->head;
              curr_dim++;
          } /* end while */
      } /* end else */
  
      /* Calculate offset of selection in projected buffer */
      *offset = H5VM_array_offset(space->extent.rank, space->extent.size, block); 
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_project_scalar() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_hyper_project_simple_lower
   *
   * Purpose:	Projects a hyperslab selection onto/into a simple dataspace
   *              of a lower rank
   *
   * Return:	non-negative on success, negative on failure.
   *
   * Programmer:	Quincey Koziol
   *              Sunday, July 18, 2010
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_hyper_project_simple_lower(const H5S_t *base_space, H5S_t *new_space)
  {
      H5S_hyper_span_info_t *down;        /* Pointer to list of spans */
      unsigned curr_dim;                  /* Current dimension being operated on */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(base_space && H5S_SEL_HYPERSLABS == H5S_GET_SELECT_TYPE(base_space));
      HDassert(new_space);
      HDassert(new_space->extent.rank < base_space->extent.rank);
  
      /* Walk down the span tree until we reach the selection to project */
      down = base_space->select.sel_info.hslab->span_lst;
      curr_dim = 0;
      while(down && curr_dim < (base_space->extent.rank - new_space->extent.rank)) {
          /* Sanity check */
          HDassert(NULL == down->head->next);
  
          /* Advance down to next dimension */
          down = down->head->down;
          curr_dim++;
      } /* end while */
      HDassert(down);
  
      /* Share the underlying hyperslab span information */
      new_space->select.sel_info.hslab->span_lst = down;
      new_space->select.sel_info.hslab->span_lst->count++;
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_project_simple_lower() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_hyper_project_simple_higher
   *
   * Purpose:	Projects a hyperslab selection onto/into a simple dataspace
   *              of a higher rank
   *
   * Return:	non-negative on success, negative on failure.
   *
   * Programmer:	Quincey Koziol
   *              Sunday, July 18, 2010
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_hyper_project_simple_higher(const H5S_t *base_space, H5S_t *new_space)
  {
      H5S_hyper_span_t *prev_span = NULL; /* Pointer to previous list of spans */
      unsigned curr_dim;                  /* Current dimension being operated on */
      herr_t ret_value = SUCCEED;         /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Check args */
      HDassert(base_space && H5S_SEL_HYPERSLABS == H5S_GET_SELECT_TYPE(base_space));
      HDassert(new_space);
      HDassert(new_space->extent.rank > base_space->extent.rank);
  
      /* Create nodes until reaching the correct # of dimensions */
      new_space->select.sel_info.hslab->span_lst = NULL;
      curr_dim = 0;
      while(curr_dim < (new_space->extent.rank - base_space->extent.rank)) {
          H5S_hyper_span_info_t *new_span_info;  /* Pointer to list of spans */
          H5S_hyper_span_t *new_span;     /* Temporary hyperslab span */
  
          /* Allocate a new span_info node */
          if(NULL == (new_span_info = H5FL_MALLOC(H5S_hyper_span_info_t))) {
              if(prev_span)
                  if(H5S_hyper_free_span(prev_span) < 0)
                      HERROR(H5E_DATASPACE, H5E_CANTFREE, "can't free hyperslab span");
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL, "can't allocate hyperslab span info")
          } /* end if */
  
          /* Check for linking into higher span */
          if(prev_span)
              prev_span->down = new_span_info;
  
          /* Allocate a new node */
          if(NULL == (new_span = H5S_hyper_new_span(0, 0, NULL, NULL))) {
              HDassert(new_span_info);
              if(!prev_span)
                  (void)H5FL_FREE(H5S_hyper_span_info_t, new_span_info);
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, FAIL, "can't allocate hyperslab span")
          } /* end if */
  
          /* Set the span_info information */
          new_span_info->count = 1;
          new_span_info->scratch = NULL;
          new_span_info->head = new_span;
  
          /* Attach to new space, if top span info */
          if(NULL == new_space->select.sel_info.hslab->span_lst)
              new_space->select.sel_info.hslab->span_lst = new_span_info;
  
          /* Remember previous span info */
          prev_span = new_span;
  
          /* Advance to next dimension */
          curr_dim++;
      } /* end while */
      HDassert(new_space->select.sel_info.hslab->span_lst);
      HDassert(prev_span);
  
      /* Share the underlying hyperslab span information */
      prev_span->down = base_space->select.sel_info.hslab->span_lst;
      prev_span->down->count++;
  
  done:
      if(ret_value < 0 && new_space->select.sel_info.hslab->span_lst) {
          if(new_space->select.sel_info.hslab->span_lst->head)
              if(H5S_hyper_free_span(
                      new_space->select.sel_info.hslab->span_lst->head) < 0)
                  HDONE_ERROR(H5E_DATASPACE, H5E_CANTFREE, FAIL, "can't free hyperslab span")
  
          new_space->select.sel_info.hslab->span_lst = H5FL_FREE(H5S_hyper_span_info_t, new_space->select.sel_info.hslab->span_lst);
      } /* end if */
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_project_simple_higher() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_hyper_project_simple
   *
   * Purpose:	Projects a hyperslab selection onto/into a simple dataspace
   *              of a different rank
   *
   * Return:	non-negative on success, negative on failure.
   *
   * Programmer:	Quincey Koziol
   *              Sunday, July 18, 2010
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_hyper_project_simple(const H5S_t *base_space, H5S_t *new_space, hsize_t *offset)
  {
      herr_t ret_value = SUCCEED;         /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Check args */
      HDassert(base_space && H5S_SEL_HYPERSLABS == H5S_GET_SELECT_TYPE(base_space));
      HDassert(new_space);
      HDassert(offset);
  
      /* We are setting a new selection, remove any current selection in new dataspace */
      if(H5S_SELECT_RELEASE(new_space) < 0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't release selection")
  
      /* Allocate space for the hyperslab selection information */
      if(NULL == (new_space->select.sel_info.hslab = H5FL_MALLOC(H5S_hyper_sel_t)))
          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab info")
  
      /* Check for a "regular" hyperslab selection */
      if(base_space->select.sel_info.hslab->diminfo_valid) {
          unsigned base_space_dim;    /* Current dimension in the base dataspace */
          unsigned new_space_dim;     /* Current dimension in the new dataspace */
  
          /* Check if the new space's rank is < or > base space's rank */
          if(new_space->extent.rank < base_space->extent.rank) {
              const H5S_hyper_dim_t *opt_diminfo = base_space->select.sel_info.hslab->opt_diminfo; /* Alias for dataspace's diminfo information */
              hsize_t block[H5S_MAX_RANK];     /* Block selected in base dataspace */
              unsigned u;         /* Local index variable */
  
              /* Compute the offset for the down-projection */
              HDmemset(block, 0, sizeof(block));
              for(u = 0; u < (base_space->extent.rank - new_space->extent.rank); u++)
                  block[u] = opt_diminfo[u].start;
              *offset = H5VM_array_offset(base_space->extent.rank, base_space->extent.size, block); 
  
              /* Set the correct dimensions for the base & new spaces */
              base_space_dim = base_space->extent.rank - new_space->extent.rank;
              new_space_dim = 0;
          } /* end if */
          else {
              HDassert(new_space->extent.rank > base_space->extent.rank);
  
              /* The offset is zero when projected into higher dimensions */
              *offset = 0;
  
              /* Set the diminfo information for the higher dimensions */
              for(new_space_dim = 0; new_space_dim < (new_space->extent.rank - base_space->extent.rank); new_space_dim++) {
                  new_space->select.sel_info.hslab->app_diminfo[new_space_dim].start = 0;
                  new_space->select.sel_info.hslab->app_diminfo[new_space_dim].stride = 1;
                  new_space->select.sel_info.hslab->app_diminfo[new_space_dim].count = 1;
                  new_space->select.sel_info.hslab->app_diminfo[new_space_dim].block = 1;
  
                  new_space->select.sel_info.hslab->opt_diminfo[new_space_dim].start = 0;
                  new_space->select.sel_info.hslab->opt_diminfo[new_space_dim].stride = 1;
                  new_space->select.sel_info.hslab->opt_diminfo[new_space_dim].count = 1;
                  new_space->select.sel_info.hslab->opt_diminfo[new_space_dim].block = 1;
              } /* end for */
  
              /* Start at beginning of base space's dimension info */
              base_space_dim = 0;
          } /* end else */
  
          /* Copy the diminfo */
          while(base_space_dim < base_space->extent.rank) {
              new_space->select.sel_info.hslab->app_diminfo[new_space_dim].start = 
                      base_space->select.sel_info.hslab->app_diminfo[base_space_dim].start;
              new_space->select.sel_info.hslab->app_diminfo[new_space_dim].stride = 
                      base_space->select.sel_info.hslab->app_diminfo[base_space_dim].stride;
              new_space->select.sel_info.hslab->app_diminfo[new_space_dim].count = 
                      base_space->select.sel_info.hslab->app_diminfo[base_space_dim].count;
              new_space->select.sel_info.hslab->app_diminfo[new_space_dim].block = 
                      base_space->select.sel_info.hslab->app_diminfo[base_space_dim].block;
  
              new_space->select.sel_info.hslab->opt_diminfo[new_space_dim].start = 
                      base_space->select.sel_info.hslab->opt_diminfo[base_space_dim].start;
              new_space->select.sel_info.hslab->opt_diminfo[new_space_dim].stride =
                      base_space->select.sel_info.hslab->opt_diminfo[base_space_dim].stride;
              new_space->select.sel_info.hslab->opt_diminfo[new_space_dim].count = 
                      base_space->select.sel_info.hslab->opt_diminfo[base_space_dim].count;
              new_space->select.sel_info.hslab->opt_diminfo[new_space_dim].block = 
                      base_space->select.sel_info.hslab->opt_diminfo[base_space_dim].block;
  
              /* Advance to next dimensions */
              base_space_dim++;
              new_space_dim++;
          } /* end for */
  
          /* Indicate that the dimension information is valid */
          new_space->select.sel_info.hslab->diminfo_valid = TRUE;
  
          /* Indicate that there's no slab information */
          new_space->select.sel_info.hslab->span_lst = NULL;
      } /* end if */
      else {
          /* Check if the new space's rank is < or > base space's rank */
          if(new_space->extent.rank < base_space->extent.rank) {
              const H5S_hyper_span_t *curr;    /* Pointer to current hyperslab span */
              hsize_t block[H5S_MAX_RANK];     /* Block selected in base dataspace */
              unsigned curr_dim;               /* Current dimension being operated on */
  
              /* Clear the block buffer */
              HDmemset(block, 0, sizeof(block));
  
              /* Advance down selected spans */
              curr = base_space->select.sel_info.hslab->span_lst->head;
              curr_dim = 0;
              while(curr && curr_dim < (base_space->extent.rank - new_space->extent.rank)) {
                  /* Save the location of the selection in current dimension */
                  block[curr_dim] = curr->low;
  
                  /* Advance down to next dimension */
                  curr = curr->down->head;
                  curr_dim++;
              } /* end while */
  
              /* Compute the offset for the down-projection */
              *offset = H5VM_array_offset(base_space->extent.rank, base_space->extent.size, block); 
  
              /* Project the base space's selection down in less dimensions */
              if(H5S_hyper_project_simple_lower(base_space, new_space) < 0)
                  HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSELECT, FAIL, "can't project hyperslab selection into less dimensions")
          } /* end if */
          else {
              HDassert(new_space->extent.rank > base_space->extent.rank);
  
              /* The offset is zero when projected into higher dimensions */
              *offset = 0;
  
              /* Project the base space's selection down in less dimensions */
              if(H5S_hyper_project_simple_higher(base_space, new_space) < 0)
                  HGOTO_ERROR(H5E_DATASPACE, H5E_CANTSELECT, FAIL, "can't project hyperslab selection into less dimensions")
          } /* end else */
  
          /* Indicate that the dimension information is not valid */
          new_space->select.sel_info.hslab->diminfo_valid = FALSE;
      } /* end else */
  
      /* Number of elements selected will be the same */
      new_space->select.num_elem = base_space->select.num_elem;
  
      /* Set selection type */
      new_space->select.type = H5S_sel_hyper;
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_project_simple() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_adjust_helper_s
   PURPOSE
      Helper routine to adjust offsets in span trees
   USAGE
      herr_t H5S_hyper_adjust_helper_s(spans, offset)
          H5S_hyper_span_info_t *spans;   IN: Span tree to operate with
          const hssize_t *offset;         IN: Offset to subtract
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Adjust the location of the spans in a span tree by subtracting an offset
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_adjust_helper_s(H5S_hyper_span_info_t *spans, const hssize_t *offset)
  {
      H5S_hyper_span_t *span;     /* Pointer to current span in span tree */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Sanity check */
      HDassert(spans);
      HDassert(offset);
  
      /* Check if we've already set this down span tree */
      if(spans->scratch != (H5S_hyper_span_info_t *)~((size_t)NULL)) {
          /* Set the tree's scratch pointer */
          spans->scratch = (H5S_hyper_span_info_t *)~((size_t)NULL);
  
          /* Get the span lists for each span in this tree */
          span = spans->head;
  
          /* Iterate over the spans in tree */
          while(span != NULL) {
              /* Adjust span offset */
              HDassert((hssize_t)span->low >= *offset);
              span->low = (hsize_t)((hssize_t)span->low - *offset);
              span->high = (hsize_t)((hssize_t)span->high - *offset);
  
              /* Recursively adjust spans in next dimension down */
              if(span->down != NULL)
                  H5S_hyper_adjust_helper_s(span->down, offset + 1);
  
              /* Advance to next span in this dimension */
              span = span->next;
          } /* end while */
      } /* end if */
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_adjust_helper_s() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_adjust_s
   PURPOSE
      Adjust a hyperslab selection by subtracting an offset
   USAGE
      herr_t H5S_hyper_adjust_s(space,offset)
          H5S_t *space;           IN/OUT: Pointer to dataspace to adjust
          const hssize_t *offset; IN: Offset to subtract
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Moves a hyperslab selection by subtracting an offset from it.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  herr_t
  H5S_hyper_adjust_s(H5S_t *space, const hssize_t *offset)
  {
      unsigned u;                         /* Local index variable */
      herr_t      ret_value = SUCCEED;    /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(space);
      HDassert(offset);
  
      /* Subtract the offset from the "regular" coordinates, if they exist */
      if(space->select.sel_info.hslab->diminfo_valid) {
          for(u = 0; u < space->extent.rank; u++) {
              HDassert((hssize_t)space->select.sel_info.hslab->opt_diminfo[u].start >= offset[u]);
              space->select.sel_info.hslab->opt_diminfo[u].start = (hsize_t)((hssize_t)space->select.sel_info.hslab->opt_diminfo[u].start - offset[u]);
          } /* end for */
      } /* end if */
  
      /* Subtract the offset from the span tree coordinates, if they exist */
      if(space->select.sel_info.hslab->span_lst) {
          if(H5S_hyper_adjust_helper_s(space->select.sel_info.hslab->span_lst, offset) < 0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_BADSELECT, FAIL, "can't perform hyperslab offset adjustment")
  
          /* Reset the scratch pointers for the next routine which needs them */
          H5S_hyper_span_scratch(space->select.sel_info.hslab->span_lst, NULL);
      } /* end if */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_adjust_s() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_normalize_offset
   PURPOSE
      "Normalize" a hyperslab selection by adjusting it's coordinates by the
      amount of the selection offset.
   USAGE
      herr_t H5S_hyper_normalize_offset(space, old_offset)
          H5S_t *space;           IN/OUT: Pointer to dataspace to move
          hssize_t *old_offset;   OUT: Pointer to space to store old offset
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Copies the current selection offset into the array provided, then
      inverts the selection offset, subtracts the offset from the hyperslab
      selection and resets the offset to zero.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  htri_t
  H5S_hyper_normalize_offset(H5S_t *space, hssize_t *old_offset)
  {
      unsigned u;                         /* Local index variable */
      herr_t ret_value = FALSE;           /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(space);
  
      /* Check for hyperslab selection & offset changed */
      if(H5S_GET_SELECT_TYPE(space) == H5S_SEL_HYPERSLABS && space->select.offset_changed) {
          /* Copy & invert the selection offset */
          for(u = 0; u<space->extent.rank; u++) {
              old_offset[u] = space->select.offset[u];
              space->select.offset[u] = -space->select.offset[u];
          } /* end for */
  
          /* Call the existing 'adjust' routine */
          if(H5S_hyper_adjust_s(space, space->select.offset) < 0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_BADSELECT, FAIL, "can't perform hyperslab normalization")
  
          /* Zero out the selection offset */
          HDmemset(space->select.offset, 0, sizeof(hssize_t) * space->extent.rank);
  
          /* Indicate that the offset was normalized */
          ret_value = TRUE;
      } /* end if */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_normalize_offset() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_denormalize_offset
   PURPOSE
      "Denormalize" a hyperslab selection by reverse adjusting it's coordinates
      by the amount of the former selection offset.
   USAGE
      herr_t H5S_hyper_normalize_offset(space, old_offset)
          H5S_t *space;           IN/OUT: Pointer to dataspace to move
          hssize_t *old_offset;   IN: Pointer to old offset array
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Subtracts the old offset from the current selection (canceling out the
      effect of the "normalize" routine), then restores the old offset into
      the dataspace.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  herr_t
  H5S_hyper_denormalize_offset(H5S_t *space, const hssize_t *old_offset)
  {
      herr_t      ret_value = SUCCEED;    /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(space);
      HDassert(H5S_GET_SELECT_TYPE(space) == H5S_SEL_HYPERSLABS);
  
      /* Call the existing 'adjust' routine */
      if(H5S_hyper_adjust_s(space, old_offset) < 0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_BADSELECT, FAIL, "can't perform hyperslab normalization")
  
      /* Copy the selection offset over */
      HDmemcpy(space->select.offset, old_offset, sizeof(hssize_t) * space->extent.rank);
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_denormalize_offset() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_append_span
   PURPOSE
      Create a new span and append to span list
   USAGE
      herr_t H5S_hyper_append_span(prev_span, span_tree, low, high, down, next)
          H5S_hyper_span_t **prev_span;    IN/OUT: Pointer to previous span in list
          H5S_hyper_span_info_t **span_tree;  IN/OUT: Pointer to span tree to append to
          hsize_t low, high;         IN: Low and high bounds for new span node
          H5S_hyper_span_info_t *down;     IN: Down span tree for new node
          H5S_hyper_span_t *next;     IN: Next span for new node
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Create a new span node and append to a span list.  Update the previous
      span in the list also.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_append_span (H5S_hyper_span_t **prev_span, H5S_hyper_span_info_t ** span_tree, hsize_t low, hsize_t high, H5S_hyper_span_info_t *down, H5S_hyper_span_t *next)
  {
      H5S_hyper_span_t *new_span = NULL;
      herr_t      ret_value = SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(prev_span);
      HDassert(span_tree);
  
      /* Check for adding first node to merged spans */
      if(*prev_span==NULL) {
          /* Allocate new span node to append to list */
          if((new_span = H5S_hyper_new_span(low,high,down,next))==NULL)
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
          /* Make first node in span list */
  
          /* Check that we haven't already allocated a span tree */
          HDassert(*span_tree==NULL);
  
          /* Allocate a new span_info node */
          if((*span_tree = H5FL_MALLOC(H5S_hyper_span_info_t))==NULL)
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
          /* Set the span tree's basic information */
          (*span_tree)->count=1;
          (*span_tree)->scratch=NULL;
          (*span_tree)->head=new_span;
  
          /* Update previous merged span */
          *prev_span=new_span;
      } /* end if */
      /* Merge or append to existing merged spans list */
      else {
          /* Check if span can just extend the previous merged span */
          if((((*prev_span)->high+1)==low) &&
                  H5S_hyper_cmp_spans(down,(*prev_span)->down)==TRUE) {
              /* Extend previous merged span to include new high bound */
              (*prev_span)->high=high;
              (*prev_span)->nelem+=(high-low)+1;
          } /* end if */
          else {
              /* Allocate new span node to append to list */
              if((new_span = H5S_hyper_new_span(low,high,down,next))==NULL)
                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
              /* Check if there is actually a down span */
              if(new_span->down) {
                  /* Check if the down spans for the new span node are the same as the previous span node */
                  if(H5S_hyper_cmp_spans(new_span->down,(*prev_span)->down)==TRUE) {
                      /* Release the down span for the new node */
                      H5S_hyper_free_span_info(new_span->down);
  
                      /* Point the new node's down span at the previous node's down span */
                      new_span->down=(*prev_span)->down;
  
                      /* Increment the reference count to the shared down span */
                      new_span->down->count++;
                  } /* end if */
              } /* end if */
  
              /* Indicate elements from previous span */
              new_span->pstride=low-(*prev_span)->low;
  
              /* Append to end of merged spans list */
              (*prev_span)->next=new_span;
              *prev_span=new_span;
          } /* end else */
      } /* end else */
  
  done:
      if(ret_value < 0) {
          if(new_span)
              if(H5S_hyper_free_span(new_span) < 0)
                  HDONE_ERROR(H5E_DATASPACE, H5E_CANTFREE, FAIL, "failed to release new hyperslab span")
      } /* end if */
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_append_span() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_clip_spans
   PURPOSE
      Clip a new span tree against the current spans in the hyperslab selection
   USAGE
      herr_t H5S_hyper_clip_spans(span_a, span_b, a_not_b, a_and_b, b_not_a)
          H5S_hyper_span_t *a_spans;    IN: Span tree 'a' to clip with.
          H5S_hyper_span_t *b_spans;    IN: Span tree 'b' to clip with.
          H5S_hyper_span_t **a_not_b;  OUT: Span tree of 'a' hyperslab spans which
                                              doesn't overlap with 'b' hyperslab
                                              spans.
          H5S_hyper_span_t **a_and_b;  OUT: Span tree of 'a' hyperslab spans which
                                              overlaps with 'b' hyperslab spans.
          H5S_hyper_span_t **b_not_a;  OUT: Span tree of 'b' hyperslab spans which
                                              doesn't overlap with 'a' hyperslab
                                              spans.
   RETURNS
      non-negative on success, negative on failure
   DESCRIPTION
      Clip one span tree ('a') against another span tree ('b').  Creates span
      trees for the area defined by the 'a' span tree which does not overlap the
      'b' span tree, the area defined by the overlap of the 'a' hyperslab span
      tree and the 'b' span tree, and the area defined by the 'b' hyperslab span
      tree which does not overlap the 'a' span tree.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_clip_spans (H5S_hyper_span_info_t *a_spans, H5S_hyper_span_info_t *b_spans,
      H5S_hyper_span_info_t **a_not_b, H5S_hyper_span_info_t **a_and_b,
      H5S_hyper_span_info_t **b_not_a)
  {
      H5S_hyper_span_t *span_a;   /* Pointer to a node in span tree 'a' */
      H5S_hyper_span_t *span_b;   /* Pointer to a node in span tree 'b' */
      H5S_hyper_span_t *tmp_span; /* Temporary pointer to new span */
      H5S_hyper_span_t *last_a_not_b;   /* Pointer to previous node in span tree 'a_not_b' */
      H5S_hyper_span_t *last_a_and_b;   /* Pointer to previous node in span tree 'a_and_b' */
      H5S_hyper_span_t *last_b_not_a;   /* Pointer to previous node in span tree 'b_not_a' */
      H5S_hyper_span_info_t *down_a_not_b; /* Temporary pointer to a_not_b span tree of down spans for overlapping nodes */
      H5S_hyper_span_info_t *down_a_and_b; /* Temporary pointer to a_and_b span tree of down spans for overlapping nodes */
      H5S_hyper_span_info_t *down_b_not_a; /* Temporary pointer to b_and_a span tree of down spans for overlapping nodes */
      unsigned recover_a, recover_b;         /* Flags to indicate when to recover temporary spans */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Check args */
      HDassert(a_spans);
      HDassert(b_spans);
      HDassert(a_not_b);
      HDassert(a_and_b);
      HDassert(b_not_a);
  
      /* Check if both span trees are not defined */
      if(a_spans==NULL && b_spans==NULL) {
          *a_not_b=NULL;
          *a_and_b=NULL;
          *b_not_a=NULL;
      } /* end if */
      /* If span 'a' is not defined, but 'b' is, copy 'b' and set the other return span trees to empty */
      else if(a_spans==NULL) {
          *a_not_b=NULL;
          *a_and_b=NULL;
          if((*b_not_a=H5S_hyper_copy_span(b_spans))==NULL)
              HGOTO_ERROR(H5E_INTERNAL, H5E_CANTCOPY, FAIL, "can't copy hyperslab span tree")
      } /* end if */
      /* If span 'b' is not defined, but 'a' is, copy 'a' and set the other return span trees to empty */
      else if(b_spans==NULL) {
          if((*a_not_b=H5S_hyper_copy_span(a_spans))==NULL)
              HGOTO_ERROR(H5E_INTERNAL, H5E_CANTCOPY, FAIL, "can't copy hyperslab span tree")
          *a_and_b=NULL;
          *b_not_a=NULL;
      } /* end if */
      /* If span 'a' and 'b' are both defined, calculate the proper span trees */
      else {
          /* Check if both span trees completely overlap */
          if(H5S_hyper_cmp_spans(a_spans,b_spans)==TRUE) {
              *a_not_b=NULL;
              if((*a_and_b=H5S_hyper_copy_span(a_spans))==NULL)
                  HGOTO_ERROR(H5E_INTERNAL, H5E_CANTCOPY, FAIL, "can't copy hyperslab span tree")
              *b_not_a=NULL;
          } /* end if */
          else {
              /* Get the pointers to the new and old span lists */
              span_a=a_spans->head;
              span_b=b_spans->head;
  
              /* Set the pointer to the previous spans */
              last_a_not_b=NULL;
              last_a_and_b=NULL;
              last_b_not_a=NULL;
  
              /* No spans to recover yet */
              recover_a=recover_b=0;
  
              /* Work through the list of spans in the new list */
              while(span_a!=NULL && span_b!=NULL) {
                  /* Check if span 'a' is completely before span 'b' */
                  /*    AAAAAAA                            */
                  /* <-----------------------------------> */
                  /*             BBBBBBBBBB                */
                  if(span_a->high<span_b->low) {
                      /* Copy span 'a' and add to a_not_b list */
  
                      /* Merge/add span 'a' with/to a_not_b list */
                      if(H5S_hyper_append_span(&last_a_not_b,a_not_b,span_a->low,span_a->high,span_a->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                      /* Advance span 'a', leave span 'b' */
                      H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
                  } /* end if */
                  /* Check if span 'a' overlaps only the lower bound */
                  /*  of span 'b' , up to the upper bound of span 'b' */
                  /*    AAAAAAAAAAAA                       */
                  /* <-----------------------------------> */
                  /*             BBBBBBBBBB                */
                  else if(span_a->low<span_b->low && (span_a->high>=span_b->low && span_a->high<=span_b->high)) {
                      /* Split span 'a' into two parts at the low bound of span 'b' */
  
                      /* Merge/add lower part of span 'a' with/to a_not_b list */
                      if(H5S_hyper_append_span(&last_a_not_b,a_not_b,span_a->low,span_b->low-1,span_a->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                      /* Check for overlaps between upper part of span 'a' and lower part of span 'b' */
  
                      /* Make certain both spans either have a down span or both don't have one */
                      HDassert((span_a->down != NULL && span_b->down != NULL) || (span_a->down == NULL && span_b->down == NULL));
  
                      /* If there are no down spans, just add the overlapping area to the a_and_b list */
                      if(span_a->down==NULL) {
                          /* Merge/add overlapped part with/to a_and_b list */
                          if(H5S_hyper_append_span(&last_a_and_b,a_and_b,span_b->low,span_a->high,NULL,NULL)==FAIL)
                              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
                      } /* end if */
                      /* If there are down spans, check for the overlap in them and add to each appropriate list */
                      else {
                          /* NULL out the temporary pointers to clipped areas in down spans */
                          down_a_not_b=NULL;
                          down_a_and_b=NULL;
                          down_b_not_a=NULL;
  
                          /* Check for overlaps in the 'down spans' of span 'a' & 'b' */
                          if(H5S_hyper_clip_spans(span_a->down,span_b->down,&down_a_not_b,&down_a_and_b,&down_b_not_a)<0)
                              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't clip hyperslab information")
  
                          /* Check for additions to the a_not_b list */
                          if(down_a_not_b!=NULL) {
                              /* Merge/add overlapped part with/to a_not_b list */
                              if(H5S_hyper_append_span(&last_a_not_b,a_not_b,span_b->low,span_a->high,down_a_not_b,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_a_not_b);
                          } /* end if */
  
                          /* Check for additions to the a_and_b list */
                          if(down_a_and_b!=NULL) {
                              /* Merge/add overlapped part with/to a_and_b list */
                              if(H5S_hyper_append_span(&last_a_and_b,a_and_b,span_b->low,span_a->high,down_a_and_b,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_a_and_b);
                          } /* end if */
  
                          /* Check for additions to the b_not_a list */
                          if(down_b_not_a!=NULL) {
                              /* Merge/add overlapped part with/to b_not_a list */
                              if(H5S_hyper_append_span(&last_b_not_a,b_not_a,span_b->low,span_a->high,down_b_not_a,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_b_not_a);
                          } /* end if */
                      } /* end else */
  
                      /* Split off upper part of span 'b' at upper span of span 'a' */
  
                      /* Check if there is actually an upper part of span 'b' to split off */
                      if(span_a->high<span_b->high) {
                          /* Allocate new span node for upper part of span 'b' */
                          if((tmp_span = H5S_hyper_new_span(span_a->high+1,span_b->high,span_b->down,span_b->next))==NULL)
                              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                          /* Advance span 'a' */
                          H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
  
                          /* Make upper part of span 'b' into new span 'b' */
                          H5S_hyper_recover_span(&recover_b,&span_b,tmp_span);
                          recover_b=1;
                      } /* end if */
                      /* No upper part of span 'b' to split */
                      else {
                          /* Advance both 'a' and 'b' */
                          H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
                          H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
                      } /* end else */
                  } /* end if */
                  /* Check if span 'a' overlaps the lower & upper bound */
                  /*  of span 'b' */
                  /*    AAAAAAAAAAAAAAAAAAAAA              */
                  /* <-----------------------------------> */
                  /*             BBBBBBBBBB                */
                  else if(span_a->low<span_b->low && span_a->high>span_b->high) {
                      /* Split off lower part of span 'a' at lower span of span 'b' */
  
                      /* Merge/add lower part of span 'a' with/to a_not_b list */
                      if(H5S_hyper_append_span(&last_a_not_b,a_not_b,span_a->low,span_b->low-1,span_a->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                      /* Check for overlaps between middle part of span 'a' and span 'b' */
  
                      /* Make certain both spans either have a down span or both don't have one */
                      HDassert((span_a->down != NULL && span_b->down != NULL) || (span_a->down == NULL && span_b->down == NULL));
  
                      /* If there are no down spans, just add the overlapping area to the a_and_b list */
                      if(span_a->down==NULL) {
                          /* Merge/add overlapped part with/to a_and_b list */
                          if(H5S_hyper_append_span(&last_a_and_b,a_and_b,span_b->low,span_b->high,NULL,NULL)==FAIL)
                              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
                      } /* end if */
                      /* If there are down spans, check for the overlap in them and add to each appropriate list */
                      else {
                          /* NULL out the temporary pointers to clipped areas in down spans */
                          down_a_not_b=NULL;
                          down_a_and_b=NULL;
                          down_b_not_a=NULL;
  
                          /* Check for overlaps in the 'down spans' of span 'a' & 'b' */
                          if(H5S_hyper_clip_spans(span_a->down,span_b->down,&down_a_not_b,&down_a_and_b,&down_b_not_a)<0)
                              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't clip hyperslab information")
  
                          /* Check for additions to the a_not_b list */
                          if(down_a_not_b!=NULL) {
                              /* Merge/add overlapped part with/to a_not_b list */
                              if(H5S_hyper_append_span(&last_a_not_b,a_not_b,span_b->low,span_b->high,down_a_not_b,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_a_not_b);
                          } /* end if */
  
                          /* Check for additions to the a_and_b list */
                          if(down_a_and_b!=NULL) {
                              /* Merge/add overlapped part with/to a_and_b list */
                              if(H5S_hyper_append_span(&last_a_and_b,a_and_b,span_b->low,span_b->high,down_a_and_b,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_a_and_b);
                          } /* end if */
  
                          /* Check for additions to the b_not_a list */
                          if(down_b_not_a!=NULL) {
                              /* Merge/add overlapped part with/to b_not_a list */
                              if(H5S_hyper_append_span(&last_b_not_a,b_not_a,span_b->low,span_b->high,down_b_not_a,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_b_not_a);
                          } /* end if */
                      } /* end else */
  
                      /* Split off upper part of span 'a' at upper span of span 'b' */
  
                      /* Allocate new span node for upper part of span 'a' */
                      if((tmp_span = H5S_hyper_new_span(span_b->high+1,span_a->high,span_a->down,span_a->next))==NULL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                      /* Make upper part of span 'a' the new span 'a' */
                      H5S_hyper_recover_span(&recover_a,&span_a,tmp_span);
                      recover_a=1;
  
                      /* Advance span 'b' */
                      H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
                  } /* end if */
                  /* Check if span 'a' is entirely within span 'b' */
                  /*                AAAAA                  */
                  /* <-----------------------------------> */
                  /*             BBBBBBBBBB                */
                  else if(span_a->low>=span_b->low && span_a->high<=span_b->high) {
                      /* Split off lower part of span 'b' at lower span of span 'a' */
  
                      /* Check if there is actually a lower part of span 'b' to split off */
                      if(span_a->low>span_b->low) {
                          /* Merge/add lower part of span 'b' with/to b_not_a list */
                          if(H5S_hyper_append_span(&last_b_not_a,b_not_a,span_b->low,span_a->low-1,span_b->down,NULL)==FAIL)
                              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
                      } /* end if */
                      else {
                          /* Keep going, nothing to split off */
                      } /* end else */
  
                      /* Check for overlaps between span 'a' and midle of span 'b' */
  
                      /* Make certain both spans either have a down span or both don't have one */
                      HDassert((span_a->down != NULL && span_b->down != NULL) || (span_a->down == NULL && span_b->down == NULL));
  
                      /* If there are no down spans, just add the overlapping area to the a_and_b list */
                      if(span_a->down==NULL) {
                          /* Merge/add overlapped part with/to a_and_b list */
                          if(H5S_hyper_append_span(&last_a_and_b,a_and_b,span_a->low,span_a->high,NULL,NULL)==FAIL)
                              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
                      } /* end if */
                      /* If there are down spans, check for the overlap in them and add to each appropriate list */
                      else {
                          /* NULL out the temporary pointers to clipped areas in down spans */
                          down_a_not_b=NULL;
                          down_a_and_b=NULL;
                          down_b_not_a=NULL;
  
                          /* Check for overlaps in the 'down spans' of span 'a' & 'b' */
                          if(H5S_hyper_clip_spans(span_a->down,span_b->down,&down_a_not_b,&down_a_and_b,&down_b_not_a)<0)
                              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't clip hyperslab information")
  
                          /* Check for additions to the a_not_b list */
                          if(down_a_not_b!=NULL) {
                              /* Merge/add overlapped part with/to a_not_b list */
                              if(H5S_hyper_append_span(&last_a_not_b,a_not_b,span_a->low,span_a->high,down_a_not_b,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_a_not_b);
                          } /* end if */
  
                          /* Check for additions to the a_and_b list */
                          if(down_a_and_b!=NULL) {
                              /* Merge/add overlapped part with/to a_and_b list */
                              if(H5S_hyper_append_span(&last_a_and_b,a_and_b,span_a->low,span_a->high,down_a_and_b,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_a_and_b);
                          } /* end if */
  
                          /* Check for additions to the b_not_a list */
                          if(down_b_not_a!=NULL) {
                              /* Merge/add overlapped part with/to b_not_a list */
                              if(H5S_hyper_append_span(&last_b_not_a,b_not_a,span_a->low,span_a->high,down_b_not_a,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_b_not_a);
                          } /* end if */
                      } /* end else */
  
                      /* Check if there is actually an upper part of span 'b' to split off */
                      if(span_a->high<span_b->high) {
                          /* Split off upper part of span 'b' at upper span of span 'a' */
  
                          /* Allocate new span node for upper part of spans 'a' */
                          if((tmp_span = H5S_hyper_new_span(span_a->high+1,span_b->high,span_b->down,span_b->next))==NULL)
                              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                          /* And advance span 'a' */
                          H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
  
                          /* Make upper part of span 'b' the new span 'b' */
                          H5S_hyper_recover_span(&recover_b,&span_b,tmp_span);
                          recover_b=1;
                      } /* end if */
                      else {
                          /* Advance both span 'a' & span 'b' */
                          H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
                          H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
                      } /* end else */
                  } /* end if */
                  /* Check if span 'a' overlaps only the upper bound */
                  /*  of span 'b' */
                  /*                AAAAAAAAAA             */
                  /* <-----------------------------------> */
                  /*             BBBBBBBBBB                */
                  else if((span_a->low>=span_b->low && span_a->low<=span_b->high) && span_a->high>span_b->high) {
                      /* Check if there is actually a lower part of span 'b' to split off */
                      if(span_a->low>span_b->low) {
                          /* Split off lower part of span 'b' at lower span of span 'a' */
  
                          /* Merge/add lower part of span 'b' with/to b_not_a list */
                          if(H5S_hyper_append_span(&last_b_not_a,b_not_a,span_b->low,span_a->low-1,span_b->down,NULL)==FAIL)
                              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
                      } /* end if */
                      else {
                          /* Keep going, nothing to split off */
                      } /* end else */
  
                      /* Check for overlaps between lower part of span 'a' and upper part of span 'b' */
  
                      /* Make certain both spans either have a down span or both don't have one */
                      HDassert((span_a->down != NULL && span_b->down != NULL) || (span_a->down == NULL && span_b->down == NULL));
  
                      /* If there are no down spans, just add the overlapping area to the a_and_b list */
                      if(span_a->down==NULL) {
                          /* Merge/add overlapped part with/to a_and_b list */
                          if(H5S_hyper_append_span(&last_a_and_b,a_and_b,span_a->low,span_b->high,NULL,NULL)==FAIL)
                              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
                      } /* end if */
                      /* If there are down spans, check for the overlap in them and add to each appropriate list */
                      else {
                          /* NULL out the temporary pointers to clipped areas in down spans */
                          down_a_not_b=NULL;
                          down_a_and_b=NULL;
                          down_b_not_a=NULL;
  
                          /* Check for overlaps in the 'down spans' of span 'a' & 'b' */
                          if(H5S_hyper_clip_spans(span_a->down,span_b->down,&down_a_not_b,&down_a_and_b,&down_b_not_a)<0)
                              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't clip hyperslab information")
  
                          /* Check for additions to the a_not_b list */
                          if(down_a_not_b!=NULL) {
                              /* Merge/add overlapped part with/to a_not_b list */
                              if(H5S_hyper_append_span(&last_a_not_b,a_not_b,span_a->low,span_b->high,down_a_not_b,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_a_not_b);
                          } /* end if */
  
                          /* Check for additions to the a_and_b list */
                          if(down_a_and_b!=NULL) {
                              /* Merge/add overlapped part with/to a_and_b list */
                              if(H5S_hyper_append_span(&last_a_and_b,a_and_b,span_a->low,span_b->high,down_a_and_b,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_a_and_b);
                          } /* end if */
  
                          /* Check for additions to the b_not_a list */
                          if(down_b_not_a!=NULL) {
                              /* Merge/add overlapped part with/to b_not_a list */
                              if(H5S_hyper_append_span(&last_b_not_a,b_not_a,span_a->low,span_b->high,down_b_not_a,NULL)==FAIL)
                                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                              /* Release the down span tree generated */
                              H5S_hyper_free_span_info(down_b_not_a);
                          } /* end if */
                      } /* end else */
  
                      /* Split off upper part of span 'a' at upper span of span 'b' */
  
                      /* Allocate new span node for upper part of span 'a' */
                      if((tmp_span = H5S_hyper_new_span(span_b->high+1,span_a->high,span_a->down,span_a->next))==NULL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                      /* Make upper part of span 'a' into new span 'a' */
                      H5S_hyper_recover_span(&recover_a,&span_a,tmp_span);
                      recover_a=1;
  
                      /* Advance span 'b' */
                      H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
                  } /* end if */
                  /* span 'a' must be entirely above span 'b' */
                  /*                         AAAAA         */
                  /* <-----------------------------------> */
                  /*             BBBBBBBBBB                */
                  else {
                      /* Copy span 'b' and add to b_not_a list */
  
                      /* Merge/add span 'b' with/to b_not_a list */
                      if(H5S_hyper_append_span(&last_b_not_a,b_not_a,span_b->low,span_b->high,span_b->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                      /* Advance span 'b', leave span 'a' */
                      H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
                  } /* end else */
              } /* end while */
  
              /* Clean up 'a' spans which haven't been covered yet */
              if(span_a!=NULL && span_b==NULL) {
                  while(span_a!=NULL) {
                      /* Copy span 'a' and add to a_not_b list */
  
                      /* Merge/add span 'a' with/to a_not_b list */
                      if(H5S_hyper_append_span(&last_a_not_b,a_not_b,span_a->low,span_a->high,span_a->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                      /* Advance to the next 'a' span */
                      H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
                  } /* end while */
              } /* end if */
              /* Clean up 'b' spans which haven't been covered yet */
              else if(span_a==NULL && span_b!=NULL) {
                  while(span_b!=NULL) {
                      /* Copy span 'b' and add to b_not_a list */
  
                      /* Merge/add span 'b' with/to b_not_a list */
                      if(H5S_hyper_append_span(&last_b_not_a,b_not_a,span_b->low,span_b->high,span_b->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
                      /* Advance to the next 'b' span */
                      H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
                  } /* end while */
              } /* end if */
          } /* end else */
      } /* end else */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_clip_spans() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_merge_spans_helper
   PURPOSE
      Merge two hyperslab span tree together
   USAGE
      H5S_hyper_span_info_t *H5S_hyper_merge_spans_helper(a_spans, b_spans)
          H5S_hyper_span_info_t *a_spans; IN: First hyperslab spans to merge
                                                  together
          H5S_hyper_span_info_t *b_spans; IN: Second hyperslab spans to merge
                                                  together
   RETURNS
      Pointer to span tree containing the merged spans on success, NULL on failure
   DESCRIPTION
      Merge two sets of hyperslab spans together and return the span tree from
      the merged set.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static H5S_hyper_span_info_t *
  H5S_hyper_merge_spans_helper (H5S_hyper_span_info_t *a_spans, H5S_hyper_span_info_t *b_spans)
  {
      H5S_hyper_span_info_t *merged_spans=NULL; /* Pointer to the merged span tree */
      H5S_hyper_span_info_t *tmp_spans;   /* Pointer to temporary new span tree */
      H5S_hyper_span_t *tmp_span;         /* Pointer to temporary new span */
      H5S_hyper_span_t *span_a;           /* Pointer to current span 'a' working on */
      H5S_hyper_span_t *span_b;           /* Pointer to current span 'b' working on */
      H5S_hyper_span_t *prev_span_merge;  /* Pointer to previous merged span */
      unsigned recover_a, recover_b;         /* Flags to indicate when to recover temporary spans */
      H5S_hyper_span_info_t *ret_value;
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Make certain both 'a' & 'b' spans have down span trees or neither does */
      HDassert((a_spans != NULL && b_spans != NULL) || (a_spans == NULL && b_spans == NULL));
  
      /* Check if the span trees for the 'a' span and the 'b' span are the same */
      if(H5S_hyper_cmp_spans(a_spans,b_spans)==TRUE) {
          if(a_spans==NULL)
              merged_spans=NULL;
          else {
              /* Copy one of the span trees to return */
              if((merged_spans=H5S_hyper_copy_span(a_spans))==NULL)
                  HGOTO_ERROR(H5E_INTERNAL, H5E_CANTCOPY, NULL, "can't copy hyperslab span tree")
          } /* end else */
      } /* end if */
      else {
          /* Get the pointers to the 'a' and 'b' span lists */
          span_a=a_spans->head;
          span_b=b_spans->head;
  
          /* Set the pointer to the previous spans */
          prev_span_merge=NULL;
  
          /* No spans to recover yet */
          recover_a=recover_b=0;
  
          /* Work through the list of spans in the new list */
          while(span_a!=NULL && span_b!=NULL) {
              /* Check if the 'a' span is completely before 'b' span */
              /*    AAAAAAA                            */
              /* <-----------------------------------> */
              /*             BBBBBBBBBB                */
              if(span_a->high<span_b->low) {
                  /* Merge/add span 'a' with/to the merged spans */
                  if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_a->low,span_a->high,span_a->down,NULL)==FAIL)
                      HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                  /* Advance span 'a' */
                  H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
              } /* end if */
              /* Check if span 'a' overlaps only the lower bound */
              /*  of span 'b', up to the upper bound of span 'b' */
              /*    AAAAAAAAAAAA                       */
              /* <-----------------------------------> */
              /*             BBBBBBBBBB                */
              else if(span_a->low<span_b->low && (span_a->high>=span_b->low && span_a->high<=span_b->high)) {
                  /* Check if span 'a' and span 'b' down spans are equal */
                  if(H5S_hyper_cmp_spans(span_a->down,span_b->down)==TRUE) {
                      /* Merge/add copy of span 'a' with/to merged spans */
                      if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_a->low,span_a->high,span_a->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
                  } /* end if */
                  else {
                      /* Merge/add lower part of span 'a' with/to merged spans */
                      if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_a->low,span_b->low-1,span_a->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                      /* Get merged span tree for overlapped section */
                      tmp_spans=H5S_hyper_merge_spans_helper(span_a->down,span_b->down);
  
                      /* Merge/add overlapped section to merged spans */
                      if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_b->low,span_a->high,tmp_spans,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                      /* Release merged span tree for overlapped section */
                      H5S_hyper_free_span_info(tmp_spans);
                  } /* end else */
  
                  /* Check if there is an upper part of span 'b' */
                  if(span_a->high<span_b->high) {
                      /* Copy upper part of span 'b' as new span 'b' */
  
                      /* Allocate new span node to append to list */
                      if((tmp_span = H5S_hyper_new_span(span_a->high+1,span_b->high,span_b->down,span_b->next))==NULL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                      /* Advance span 'a' */
                      H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
  
                      /* Set new span 'b' to tmp_span */
                      H5S_hyper_recover_span(&recover_b,&span_b,tmp_span);
                      recover_b=1;
                  } /* end if */
                  else {
                      /* Advance both span 'a' & 'b' */
                      H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
                      H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
                  } /* end else */
              } /* end if */
              /* Check if span 'a' overlaps the lower & upper bound */
              /*  of span 'b' */
              /*    AAAAAAAAAAAAAAAAAAAAA              */
              /* <-----------------------------------> */
              /*             BBBBBBBBBB                */
              else if(span_a->low<span_b->low && span_a->high>span_b->high) {
                  /* Check if span 'a' and span 'b' down spans are equal */
                  if(H5S_hyper_cmp_spans(span_a->down,span_b->down)==TRUE) {
                      /* Merge/add copy of lower & middle parts of span 'a' to merged spans */
                      if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_a->low,span_b->high,span_a->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
                  } /* end if */
                  else {
                      /* Merge/add lower part of span 'a' to merged spans */
                      if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_a->low,span_b->low-1,span_a->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                      /* Get merged span tree for overlapped section */
                      tmp_spans=H5S_hyper_merge_spans_helper(span_a->down,span_b->down);
  
                      /* Merge/add overlapped section to merged spans */
                      if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_b->low,span_b->high,tmp_spans,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                      /* Release merged span tree for overlapped section */
                      H5S_hyper_free_span_info(tmp_spans);
                  } /* end else */
  
                  /* Copy upper part of span 'a' as new span 'a' (remember to free) */
  
                  /* Allocate new span node to append to list */
                  if((tmp_span = H5S_hyper_new_span(span_b->high+1,span_a->high,span_a->down,span_a->next))==NULL)
                      HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                  /* Set new span 'a' to tmp_span */
                  H5S_hyper_recover_span(&recover_a,&span_a,tmp_span);
                  recover_a=1;
  
                  /* Advance span 'b' */
                  H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
              } /* end if */
              /* Check if span 'a' is entirely within span 'b' */
              /*                AAAAA                  */
              /* <-----------------------------------> */
              /*             BBBBBBBBBB                */
              else if(span_a->low>=span_b->low && span_a->high<=span_b->high) {
                  /* Check if span 'a' and span 'b' down spans are equal */
                  if(H5S_hyper_cmp_spans(span_a->down,span_b->down)==TRUE) {
                      /* Merge/add copy of lower & middle parts of span 'b' to merged spans */
                      if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_b->low,span_a->high,span_a->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
                  } /* end if */
                  else {
                      /* Check if there is a lower part of span 'b' */
                      if(span_a->low>span_b->low) {
                          /* Merge/add lower part of span 'b' to merged spans */
                          if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_b->low,span_a->low-1,span_b->down,NULL)==FAIL)
                              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
                      } /* end if */
                      else {
                          /* No lower part of span 'b' , keep going... */
                      } /* end else */
  
                      /* Get merged span tree for overlapped section */
                      tmp_spans=H5S_hyper_merge_spans_helper(span_a->down,span_b->down);
  
                      /* Merge/add overlapped section to merged spans */
                      if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_a->low,span_a->high,tmp_spans,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                      /* Release merged span tree for overlapped section */
                      H5S_hyper_free_span_info(tmp_spans);
                  } /* end else */
  
                  /* Check if there is an upper part of span 'b' */
                  if(span_a->high<span_b->high) {
                      /* Copy upper part of span 'b' as new span 'b' (remember to free) */
  
                      /* Allocate new span node to append to list */
                      if((tmp_span = H5S_hyper_new_span(span_a->high+1,span_b->high,span_b->down,span_b->next))==NULL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                      /* Advance span 'a' */
                      H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
  
                      /* Set new span 'b' to tmp_span */
                      H5S_hyper_recover_span(&recover_b,&span_b,tmp_span);
                      recover_b=1;
                  } /* end if */
                  else {
                      /* Advance both spans */
                      H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
                      H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
                  } /* end else */
              } /* end if */
              /* Check if span 'a' overlaps only the upper bound */
              /*  of span 'b' */
              /*                AAAAAAAAAA             */
              /* <-----------------------------------> */
              /*             BBBBBBBBBB                */
              else if((span_a->low>=span_b->low && span_a->low<=span_b->high) && span_a->high>span_b->high) {
                  /* Check if span 'a' and span 'b' down spans are equal */
                  if(H5S_hyper_cmp_spans(span_a->down,span_b->down)==TRUE) {
                      /* Merge/add copy of span 'b' to merged spans if so */
                      if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_b->low,span_b->high,span_b->down,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
                  } /* end if */
                  else {
                      /* Check if there is a lower part of span 'b' */
                      if(span_a->low>span_b->low) {
                          /* Merge/add lower part of span 'b' to merged spans */
                          if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_b->low,span_a->low-1,span_b->down,NULL)==FAIL)
                              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
                      } /* end if */
                      else {
                          /* No lower part of span 'b' , keep going... */
                      } /* end else */
  
                      /* Get merged span tree for overlapped section */
                      tmp_spans=H5S_hyper_merge_spans_helper(span_a->down,span_b->down);
  
                      /* Merge/add overlapped section to merged spans */
                      if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_a->low,span_b->high,tmp_spans,NULL)==FAIL)
                          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                      /* Release merged span tree for overlapped section */
                      H5S_hyper_free_span_info(tmp_spans);
                  } /* end else */
  
                  /* Copy upper part of span 'a' as new span 'a' */
  
                  /* Allocate new span node to append to list */
                  if((tmp_span = H5S_hyper_new_span(span_b->high+1,span_a->high,span_a->down,span_a->next))==NULL)
                      HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                  /* Set new span 'a' to tmp_span */
                  H5S_hyper_recover_span(&recover_a,&span_a,tmp_span);
                  recover_a=1;
  
                  /* Advance span 'b' */
                  H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
              } /* end if */
              /* Span 'a' must be entirely above span 'b' */
              /*                         AAAAA         */
              /* <-----------------------------------> */
              /*             BBBBBBBBBB                */
              else {
                  /* Merge/add span 'b' with the merged spans */
                  if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_b->low,span_b->high,span_b->down,NULL)==FAIL)
                      HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                  /* Advance span 'b' */
                  H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
              } /* end else */
          } /* end while */
  
          /* Clean up 'a' spans which haven't been added to the list of merged spans */
          if(span_a!=NULL && span_b==NULL) {
              while(span_a!=NULL) {
                  /* Merge/add all 'a' spans into the merged spans */
                  if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_a->low,span_a->high,span_a->down,NULL)==FAIL)
                      HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                  /* Advance to next 'a' span, until all processed */
                  H5S_hyper_recover_span(&recover_a,&span_a,span_a->next);
              } /* end while */
          } /* end if */
  
          /* Clean up 'b' spans which haven't been added to the list of merged spans */
          if(span_a==NULL && span_b!=NULL) {
              while(span_b!=NULL) {
                  /* Merge/add all 'b' spans into the merged spans */
                  if(H5S_hyper_append_span(&prev_span_merge,&merged_spans,span_b->low,span_b->high,span_b->down,NULL)==FAIL)
                      HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
                  /* Advance to next 'b' span, until all processed */
                  H5S_hyper_recover_span(&recover_b,&span_b,span_b->next);
              } /* end while */
          } /* end if */
      } /* end else */
  
      /* Set return value */
      ret_value = merged_spans;
  
  done:
      if(ret_value == NULL) {
          if(merged_spans)
              if(H5S_hyper_free_span_info(merged_spans) < 0)
                  HDONE_ERROR(H5E_INTERNAL, H5E_CANTFREE, NULL, "failed to release merged hyperslab spans")
      } /* end if */
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_merge_spans_helper() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_merge_spans
   PURPOSE
      Merge new hyperslab spans to existing hyperslab selection
   USAGE
      herr_t H5S_hyper_merge_spans(space, new_spans, can_own)
          H5S_t *space;             IN: Dataspace to add new spans to hyperslab
                                          selection.
          H5S_hyper_span_t *new_spans;    IN: Span tree of new spans to add to
                                              hyperslab selection
          hbool_t can_own;        IN: Flag to indicate that it is OK to point
                                      directly to the new spans, instead of
                                      copying them.
   RETURNS
      non-negative on success, negative on failure
   DESCRIPTION
      Add a set of hyperslab spans to an existing hyperslab selection.  The
      new spans are required to be non-overlapping with the existing spans in
      the dataspace's current hyperslab selection.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_merge_spans (H5S_t *space, H5S_hyper_span_info_t *new_spans, hbool_t can_own)
  {
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(space);
      HDassert(new_spans);
  
      /* If this is the first span tree in the hyperslab selection, just use it */
      if(space->select.sel_info.hslab->span_lst==NULL) {
          if(can_own)
              space->select.sel_info.hslab->span_lst=new_spans;
          else
              space->select.sel_info.hslab->span_lst=H5S_hyper_copy_span(new_spans);
      } /* end if */
      else {
          H5S_hyper_span_info_t *merged_spans;
  
          /* Get the merged spans */
          merged_spans=H5S_hyper_merge_spans_helper(space->select.sel_info.hslab->span_lst, new_spans);
  
          /* Sanity checking since we started with some spans, we should still have some after the merge */
          HDassert(merged_spans);
  
          /* Free the previous spans */
          H5S_hyper_free_span_info(space->select.sel_info.hslab->span_lst);
  
          /* Point to the new merged spans */
          space->select.sel_info.hslab->span_lst=merged_spans;
      } /* end else */
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  }   /* H5S_hyper_merge_spans() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_spans_nelem
   PURPOSE
      Count the number of elements in a span tree
   USAGE
      hsize_t H5S_hyper_spans_nelem(spans)
          const H5S_hyper_span_info_t *spans; IN: Hyperslan span tree to count elements of
   RETURNS
      Number of elements in span tree on success; negative on failure
   DESCRIPTION
      Counts the number of elements described by the spans in a span tree.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static hsize_t
  H5S_hyper_spans_nelem (H5S_hyper_span_info_t *spans)
  {
      H5S_hyper_span_t *span;     /* Hyperslab span */
      hsize_t ret_value;
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Count the number of elements in the span tree */
      if(spans==NULL)
          ret_value=0;
      else {
          span=spans->head;
          ret_value=0;
          while(span!=NULL) {
              /* If there are down spans, multiply the size of this span by the total down span elements */
              if(span->down!=NULL)
                  ret_value+=span->nelem*H5S_hyper_spans_nelem(span->down);
              /* If there are no down spans, just count the elements in this span */
              else
                  ret_value+=span->nelem;
  
              /* Advance to next span */
              span=span->next;
          } /* end while */
      } /* end else */
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_spans_nelem() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_make_spans
   PURPOSE
      Create a span tree
   USAGE
      H5S_hyper_span_t *H5S_hyper_make_spans(rank, start, stride, count, block)
          unsigned rank;               IN: # of dimensions of the space
          const hsize_t *start;    IN: Starting location of the hyperslabs
          const hsize_t *stride;    IN: Stride from the beginning of one block to
                                          the next
          const hsize_t *count;     IN: Number of blocks
          const hsize_t *block;     IN: Size of hyperslab block
   RETURNS
      Pointer to new span tree on success, NULL on failure
   DESCRIPTION
      Generates a new span tree for the hyperslab parameters specified.
      Each span tree has a list of the elements spanned in each dimension, with
      each span node containing a pointer to the list of spans in the next
      dimension down.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static H5S_hyper_span_info_t *
  H5S_hyper_make_spans(unsigned rank, const hsize_t *start, const hsize_t *stride,
      const hsize_t *count, const hsize_t *block)
  {
      H5S_hyper_span_info_t *down = NULL;     /* Pointer to spans in next dimension down */
      H5S_hyper_span_t      *last_span;       /* Current position in hyperslab span list */
      H5S_hyper_span_t      *head = NULL;     /* Head of new hyperslab span list */
      hsize_t                stride_iter;     /* Iterator over the stride values */
      int                    i;               /* Counters */
      unsigned               u;               /* Counters */
      H5S_hyper_span_info_t *ret_value;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Check args */
      HDassert(rank > 0);
      HDassert(start);
      HDassert(stride);
      HDassert(count);
      HDassert(block);
  
      /* Start creating spans in fastest changing dimension */
      for(i = (int)(rank - 1); i >= 0; i--) {
  
          /* Sanity check */
          if(0 == count[i])
              HGOTO_ERROR(H5E_DATASPACE, H5E_BADVALUE, NULL, "count == 0 is invalid")
  
          /* Start a new list in this dimension */
          head = NULL;
          last_span = NULL;
  
          /* Generate all the span segments for this dimension */
          for(u = 0, stride_iter = 0; u < count[i]; u++, stride_iter += stride[i]) {
              H5S_hyper_span_t      *span;            /* New hyperslab span */
  
              /* Allocate a span node */
              if(NULL == (span = H5FL_MALLOC(H5S_hyper_span_t)))
                  HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, NULL, "can't allocate hyperslab span")
  
              /* Set the span's basic information */
              span->low = start[i] + stride_iter;
              span->high = span->low + (block[i] - 1);
              span->nelem = block[i];
              span->pstride = stride[i];
              span->next = NULL;
  
              /* Append to the list of spans in this dimension */
              if(head == NULL)
                  head = span;
              else
                  last_span->next = span;
  
              /* Move current pointer */
              last_span = span;
  
              /* Set the information for the next dimension down's spans, if appropriate */
              if(down != NULL) {
                  span->down = down;
                  down->count++;  /* Increment reference count for shared span */
              } /* end if */
              else {
                  span->down = NULL;
              } /* end else */
          } /* end for */
  
          /* Allocate a span info node */
          if(NULL == (down = H5FL_MALLOC(H5S_hyper_span_info_t)))
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTALLOC, NULL, "can't allocate hyperslab span")
  
          /* Set the reference count */
          down->count = 0;
  
          /* Reset the scratch pad space */
          down->scratch = 0;
  
          /* Keep the pointer to the next dimension down's completed list */
          down->head = head;
      } /* end for */
  
      /* Indicate that there is a pointer to this tree */
      down->count = 1;
  
      /* Success!  Return the head of the list in the slowest changing dimension */
      ret_value = down;
  
  done:
      /* cleanup if error (ret_value will be NULL) */
      if(!ret_value) {
          if(head || down) {
              if(head && down)
                  if(down->head != head)
                      down = NULL;
  
              do {
                  if(down) {
                      head = down->head;
                      down = H5FL_FREE(H5S_hyper_span_info_t, down);
                  } /* end if */
                  down = head->down;
  
                  while(head) {
                      last_span = head->next;
                      head = H5FL_FREE(H5S_hyper_span_t, head);
                      head = last_span;
                  } /* end while */
              } while(down);
          } /* end if */
      } /* end if */
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_make_spans() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_rebuild_helper
   PURPOSE
      Helper routine to rebuild optimized hyperslab information if possible.
      (It can be recovered with regular selection)
   USAGE
      herr_t H5S_hyper_rebuild_helper(space)
          const H5S_hyper_span_t *span;   IN: Portion of span tree to check
          H5S_hyper_dim_t span_slab[];    OUT: Rebuilt section of hyperslab description
          unsigned rank;                  IN: Current dimension to work on
   RETURNS
      >=0 on success, <0 on failure
   DESCRIPTION
      Examine the span tree for a hyperslab selection and rebuild
      the start/stride/count/block information for the selection, if possible.
  
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
      To be able to recover the optimized information, the span tree must conform
      to span tree able to be generated from a single H5S_SELECT_SET operation.
  
   EXAMPLES
   REVISION LOG
      KY, 2005/9/22
  --------------------------------------------------------------------------*/
  static hbool_t
  H5S_hyper_rebuild_helper(const H5S_hyper_span_t *span, H5S_hyper_dim_t span_slab_info[],
      unsigned rank)
  {
      hsize_t curr_stride, next_stride;
      hsize_t curr_block, next_block;
      hsize_t curr_start;
      hsize_t curr_low;
      size_t outcount;
      unsigned u;
      H5S_hyper_dim_t      canon_down_span_slab_info[H5S_MAX_RANK];
      hbool_t ret_value = TRUE;
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      if(span) {
          /* Initialization */
          curr_stride     = 1;
          curr_block      = 0;
          outcount        = 0;
          curr_low        = 0;
  
          /* Get "canonical" down span information */
          if(span->down) {
              HDassert(span->down->head);
  
              /* Go to the next down span and check whether the selection can be rebuilt.*/
              if(!H5S_hyper_rebuild_helper(span->down->head, span_slab_info, rank - 1))
                  HGOTO_DONE(FALSE)
  
              HDmemcpy(canon_down_span_slab_info, span_slab_info, sizeof(H5S_hyper_dim_t) * rank);
          } /* end if */
  
          /* Assign the initial starting point & block size */
          curr_start = span->low;
          curr_block = (span->high - span->low) + 1;
  
          /* Loop the span */
          while(span) {
              if(outcount > 0) {
                  if(span->down) {
                      H5S_hyper_dim_t      *curr_down_span_slab_info;
  
                      HDassert(span->down->head);
  
                      /* Go to the next down span and check whether the selection can be rebuilt.*/
                      if(!H5S_hyper_rebuild_helper(span->down->head, span_slab_info, rank - 1))
                          HGOTO_DONE(FALSE)
  
                      /* Compare the slab information of the adjacent spans in the down span tree.
                         We have to compare all the sub-tree slab information with the canon_down_span_slab_info.*/
  
                      for( u = 0; u < rank - 1; u++) {
                         curr_down_span_slab_info = &span_slab_info[u];
  
                         if(curr_down_span_slab_info->count > 0 && canon_down_span_slab_info[u].count > 0) {
                            if(curr_down_span_slab_info->start != canon_down_span_slab_info[u].start
                                || curr_down_span_slab_info->stride != canon_down_span_slab_info[u].stride
                                || curr_down_span_slab_info->block != canon_down_span_slab_info[u].block
                                || curr_down_span_slab_info->count != canon_down_span_slab_info[u].count)
                            HGOTO_DONE(FALSE)
                         } /* end if */
                         else if (!((curr_down_span_slab_info->count == 0) && (canon_down_span_slab_info[u].count == 0)))
                            HGOTO_DONE(FALSE)
                      }
                  } /* end if */
              } /* end if */
  
              /* Obtain values for stride and block */
              next_stride  = span->low  - curr_low;
              next_block   = (span->high - span->low) + 1;
  
              /* Compare stride and block in this span, to compare stride,
               * three spans are needed. Ignore the first two spans.
               */
              if(outcount  > 1  && curr_stride != next_stride)
                  HGOTO_DONE(FALSE)
              if(outcount != 0  && next_block  != curr_block)
                  HGOTO_DONE(FALSE)
  
              /* Keep the isolated stride to be 1 */
              if(outcount != 0)
                  curr_stride = next_stride;
  
              /* Keep current starting point */
              curr_low    = span->low;
  
              /* Advance to next span */
              span = span->next;
              outcount++;
          } /* end while */
  
          /* Save the span information. */
          span_slab_info[rank - 1].start  = curr_start;
          span_slab_info[rank - 1].count  = outcount;
          span_slab_info[rank - 1].block  = curr_block;
          span_slab_info[rank - 1].stride = curr_stride;
      } /* end if */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  } /* end H5S_hyper_rebuild_helper() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_rebuild
   PURPOSE
      Rebuild optimized hyperslab information if possible.
      (It can be recovered with regular selection)
   USAGE
      herr_t H5S_hyper_rebuild(space)
          const H5S_t *space;     IN: Dataspace to check
   RETURNS
      >=0 on success, <0 on failure
   DESCRIPTION
      Examine the span tree for a hyperslab selection and rebuild
      the start/stride/count/block information for the selection, if possible.
  
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
      To be able to recover the optimized information, the span tree must conform
      to span tree able to be generated from a single H5S_SELECT_SET operation.
  
   EXAMPLES
   REVISION LOG
  
      This routine is the optimization of the old version. The previous version
      can only detect a singluar selection. This version is general enough to
      detect any regular selection.
      KY, 2005/9/22
  --------------------------------------------------------------------------*/
  static htri_t
  H5S_hyper_rebuild(H5S_t *space)
  {
      H5S_hyper_dim_t top_span_slab_info[H5O_LAYOUT_NDIMS];
      H5S_hyper_dim_t *diminfo;
      H5S_hyper_dim_t *app_diminfo;
      unsigned rank, curr_dim;
      htri_t ret_value = TRUE;      /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(space);
      HDassert(space->select.sel_info.hslab->span_lst);
  
      /* Check the rank of space */
      rank = space->extent.rank;
  
      /* Check whether the slab can be rebuilt. Only regular selection can be rebuilt. If yes, fill in correct values.*/
      if(!H5S_hyper_rebuild_helper(space->select.sel_info.hslab->span_lst->head, top_span_slab_info, rank)) {
          HGOTO_DONE(FALSE)
      } /* end if */
      else {
          diminfo=space->select.sel_info.hslab->opt_diminfo;
          app_diminfo=space->select.sel_info.hslab->app_diminfo;
  
          for(curr_dim = 0; curr_dim < rank; curr_dim++) {
  
              app_diminfo[(rank - curr_dim) - 1].start  = diminfo[(rank - curr_dim) - 1].start = top_span_slab_info[curr_dim].start;
              app_diminfo[(rank - curr_dim) - 1].stride = diminfo[(rank - curr_dim) - 1].stride = top_span_slab_info[curr_dim].stride;
              app_diminfo[(rank - curr_dim) - 1].count  = diminfo[(rank - curr_dim) - 1].count = top_span_slab_info[curr_dim].count;
              app_diminfo[(rank - curr_dim) - 1].block  = diminfo[(rank - curr_dim) - 1].block = top_span_slab_info[curr_dim].block;
  
          } /* end for */
  
          space->select.sel_info.hslab->diminfo_valid = TRUE;
      } /* end else */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_rebuild() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_generate_spans
   PURPOSE
      Create span tree for a regular hyperslab selection
   USAGE
      herr_t H5S_hyper_generate_spans(space)
          H5S_t *space;           IN/OUT: Pointer to dataspace
   RETURNS
      Non-negative on success, negative on failure
   DESCRIPTION
      Create a span tree representation of a regular hyperslab selection and
      add it to the information for the hyperslab selection.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_generate_spans(H5S_t *space)
  {
      hsize_t tmp_start[H5O_LAYOUT_NDIMS];   /* Temporary start information */
      hsize_t tmp_stride[H5O_LAYOUT_NDIMS];   /* Temporary stride information */
      hsize_t tmp_count[H5O_LAYOUT_NDIMS];    /* Temporary count information */
      hsize_t tmp_block[H5O_LAYOUT_NDIMS];    /* Temporary block information */
      unsigned u;                             /* Counter */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      HDassert(space);
      HDassert(H5S_GET_SELECT_TYPE(space) == H5S_SEL_HYPERSLABS);
  
      /* Get the diminfo */
      for(u=0; u<space->extent.rank; u++) {
          tmp_start[u]=space->select.sel_info.hslab->opt_diminfo[u].start;
          tmp_stride[u]=space->select.sel_info.hslab->opt_diminfo[u].stride;
          tmp_count[u]=space->select.sel_info.hslab->opt_diminfo[u].count;
          tmp_block[u]=space->select.sel_info.hslab->opt_diminfo[u].block;
      } /* end for */
  
      /* Build the hyperslab information also */
      if(H5S_generate_hyperslab (space, H5S_SELECT_SET, tmp_start, tmp_stride, tmp_count, tmp_block)<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't generate hyperslabs")
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* H5S_hyper_generate_spans() */
  
  #ifndef NEW_HYPERSLAB_API
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_generate_hyperlab
   *
   * Purpose:	Generate hyperslab information from H5S_select_hyperslab()
   *
   * Return:	Non-negative on success/Negative on failure
   *
   * Programmer:	Quincey Koziol (split from HS_select_hyperslab()).
   *              Tuesday, September 12, 2000
   *
   * Modifications:
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_generate_hyperslab (H5S_t *space, H5S_seloper_t op,
  		      const hsize_t start[],
  		      const hsize_t stride[],
  		      const hsize_t count[],
  		      const hsize_t block[])
  {
      H5S_hyper_span_info_t *new_spans=NULL;  /* Span tree for new hyperslab */
      H5S_hyper_span_info_t *a_not_b=NULL;    /* Span tree for hyperslab spans in old span tree and not in new span tree */
      H5S_hyper_span_info_t *a_and_b=NULL;    /* Span tree for hyperslab spans in both old and new span trees */
      H5S_hyper_span_info_t *b_not_a=NULL;    /* Span tree for hyperslab spans in new span tree and not in old span tree */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Check args */
      HDassert(space);
      HDassert(op > H5S_SELECT_NOOP && op < H5S_SELECT_INVALID);
      HDassert(start);
      HDassert(stride);
      HDassert(count);
      HDassert(block);
  
      /* Generate span tree for new hyperslab information */
      if((new_spans=H5S_hyper_make_spans(space->extent.rank,start,stride,count,block))==NULL)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't create hyperslab information")
  
      /* Generate list of blocks to add/remove based on selection operation */
      if(op==H5S_SELECT_SET) {
          /* Add new spans to current selection */
          if(H5S_hyper_merge_spans(space,new_spans,TRUE)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
          /* Set the number of elements in current selection */
          space->select.num_elem=H5S_hyper_spans_nelem(new_spans);
  
          /* Indicate that the new_spans are owned */
          new_spans=NULL;
      } /* end if */
      else {
          hbool_t updated_spans = FALSE;  /* Whether the spans in the selection were modified */
  
          /* Generate lists of spans which overlap and don't overlap */
          if(H5S_hyper_clip_spans(space->select.sel_info.hslab->span_lst,new_spans,&a_not_b,&a_and_b,&b_not_a)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't clip hyperslab information")
  
          switch(op) {
              case H5S_SELECT_OR:
                  /* Add any new spans from b_not_a to current selection */
                  if(b_not_a!=NULL) {
                      if(H5S_hyper_merge_spans(space,b_not_a,FALSE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      space->select.num_elem+=H5S_hyper_spans_nelem(b_not_a);
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  break;
  
              case H5S_SELECT_AND:
                  /* Free the current selection */
                  if(H5S_hyper_free_span_info(space->select.sel_info.hslab->span_lst)<0)
                      HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release hyperslab spans")
                  space->select.sel_info.hslab->span_lst=NULL;
  
                  /* Reset the number of items in selection */
                  space->select.num_elem=0;
  
                  /* Check if there are any overlapped selections */
                  if(a_and_b!=NULL) {
                      if(H5S_hyper_merge_spans(space,a_and_b,TRUE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      space->select.num_elem=H5S_hyper_spans_nelem(a_and_b);
  
                      /* Indicate that the a_and_b spans are owned */
                      a_and_b=NULL;
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  break;
  
              case H5S_SELECT_XOR:
                  /* Free the current selection */
                  if(H5S_hyper_free_span_info(space->select.sel_info.hslab->span_lst)<0)
                      HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release hyperslab spans")
                  space->select.sel_info.hslab->span_lst=NULL;
  
                  /* Reset the number of items in selection */
                  space->select.num_elem=0;
  
                  /* Check if there are any non-overlapped selections */
                  if(a_not_b!=NULL) {
                      if(H5S_hyper_merge_spans(space,a_not_b,FALSE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      space->select.num_elem=H5S_hyper_spans_nelem(a_not_b);
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  if(b_not_a!=NULL) {
                      if(H5S_hyper_merge_spans(space,b_not_a,FALSE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      space->select.num_elem+=H5S_hyper_spans_nelem(b_not_a);
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  break;
  
              case H5S_SELECT_NOTB:
                  /* Free the current selection */
                  if(H5S_hyper_free_span_info(space->select.sel_info.hslab->span_lst)<0)
                      HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release hyperslab spans")
                  space->select.sel_info.hslab->span_lst=NULL;
  
                  /* Reset the number of items in selection */
                  space->select.num_elem=0;
  
                  /* Check if there are any non-overlapped selections */
                  if(a_not_b!=NULL) {
                      if(H5S_hyper_merge_spans(space,a_not_b,TRUE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      space->select.num_elem=H5S_hyper_spans_nelem(a_not_b);
  
                      /* Indicate that the a_not_b are owned */
                      a_not_b=NULL;
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  break;
  
              case H5S_SELECT_NOTA:
                  /* Free the current selection */
                  if(H5S_hyper_free_span_info(space->select.sel_info.hslab->span_lst)<0)
                      HGOTO_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release hyperslab spans")
                  space->select.sel_info.hslab->span_lst=NULL;
  
                  /* Reset the number of items in selection */
                  space->select.num_elem=0;
  
                  /* Check if there are any non-overlapped selections */
                  if(b_not_a!=NULL) {
                      if(H5S_hyper_merge_spans(space,b_not_a,TRUE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      space->select.num_elem=H5S_hyper_spans_nelem(b_not_a);
  
                      /* Indicate that the b_not_a are owned */
                      b_not_a=NULL;
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  break;
  
              case H5S_SELECT_NOOP:
              case H5S_SELECT_SET:
              case H5S_SELECT_APPEND:
              case H5S_SELECT_PREPEND:
              case H5S_SELECT_INVALID:
              default:
                  HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
          } /* end switch */
  
          /* Check if the resulting hyperslab span tree is empty */
          if(space->select.sel_info.hslab->span_lst==NULL) {
              H5S_hyper_span_info_t *spans;     /* Empty hyperslab span tree */
  
              /* Sanity check */
              HDassert(space->select.num_elem == 0);
  
              /* Allocate a span info node */
              if((spans = H5FL_MALLOC(H5S_hyper_span_info_t))==NULL)
                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span")
  
              /* Set the reference count */
              spans->count=1;
  
              /* Reset the scratch pad space */
              spans->scratch=0;
  
              /* Set to empty tree */
              spans->head=NULL;
  
              /* Set pointer to empty span tree */
              space->select.sel_info.hslab->span_lst=spans;
          } /* end if */
          else {
              /* Check if we updated the spans */
              if(updated_spans) {
                  /* Attempt to rebuild "optimized" start/stride/count/block information.
                   * from resulting hyperslab span tree
                   */
                  if(H5S_hyper_rebuild(space) < 0)
                      HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOUNT, FAIL, "can't rebuild hyperslab info")
              } /* end if */
          } /* end else */
      } /* end else */
  
  done:
      /* Free resources */
      if(a_not_b)
          if(H5S_hyper_free_span_info(a_not_b) < 0)
              HDONE_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release temporary hyperslab spans")
      if(a_and_b)
          if(H5S_hyper_free_span_info(a_and_b) < 0)
              HDONE_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release temporary hyperslab spans")
      if(b_not_a)
          if(H5S_hyper_free_span_info(b_not_a) < 0)
              HDONE_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release temporary hyperslab spans")
      if(new_spans)
          if(H5S_hyper_free_span_info(new_spans) < 0)
              HDONE_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release temporary hyperslab spans")
  
      FUNC_LEAVE_NOAPI(ret_value)
  } /* end H5S_generate_hyperslab() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_select_hyperslab
   *
   * Purpose:	Internal version of H5Sselect_hyperslab().
   *
   * Return:	Non-negative on success/Negative on failure
   *
   * Programmer:	Quincey Koziol
   *              Wednesday, January 10, 2001
   *
   *-------------------------------------------------------------------------
   */
  herr_t
  H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op,
  		      const hsize_t start[],
  		      const hsize_t *stride,
  		      const hsize_t count[],
  		      const hsize_t *block)
  {
      hsize_t int_stride[H5O_LAYOUT_NDIMS];   /* Internal storage for stride information */
      hsize_t int_count[H5O_LAYOUT_NDIMS];    /* Internal storage for count information */
      hsize_t int_block[H5O_LAYOUT_NDIMS];    /* Internal storage for block information */
      const hsize_t *opt_stride;      /* Optimized stride information */
      const hsize_t *opt_count;       /* Optimized count information */
      const hsize_t *opt_block;       /* Optimized block information */
      unsigned u;                     /* Counters */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI(FAIL)
  
      /* Check args */
      HDassert(space);
      HDassert(start);
      HDassert(count);
      HDassert(op > H5S_SELECT_NOOP && op < H5S_SELECT_INVALID);
  
      /* Point to the correct stride values */
      if(stride==NULL)
          stride = _ones;
  
      /* Point to the correct block values */
      if(block==NULL)
          block = _ones;
  
      /*
       * Check new selection.
       */
      for(u=0; u<space->extent.rank; u++) {
          /* Check for overlapping hyperslab blocks in new selection. */
          if(count[u]>1 && stride[u]<block[u])
              HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "hyperslab blocks overlap")
  
          /* Detect zero-sized hyperslabs in new selection */
          if(count[u] == 0 || block[u] == 0) {
              switch(op) {
                  case H5S_SELECT_SET:   /* Select "set" operation */
                  case H5S_SELECT_AND:   /* Binary "and" operation for hyperslabs */
                  case H5S_SELECT_NOTA:  /* Binary "B not A" operation for hyperslabs */
                      /* Convert to "none" selection */
                      if(H5S_select_none(space)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't convert selection")
                      HGOTO_DONE(SUCCEED);
  
                  case H5S_SELECT_OR:    /* Binary "or" operation for hyperslabs */
                  case H5S_SELECT_XOR:   /* Binary "xor" operation for hyperslabs */
                  case H5S_SELECT_NOTB:  /* Binary "A not B" operation for hyperslabs */
                      HGOTO_DONE(SUCCEED);        /* Selection stays same */
  
                  case H5S_SELECT_NOOP:
                  case H5S_SELECT_APPEND:
                  case H5S_SELECT_PREPEND:
                  case H5S_SELECT_INVALID:
                  default:
                      HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
              } /* end switch */
          } /* end if */
      } /* end for */
  
      /* Optimize hyperslab parameters to merge contiguous blocks, etc. */
      if(stride == _ones && block == _ones) {
          /* Point to existing arrays */
          opt_stride = _ones;
          opt_count = _ones;
          opt_block = count;
      } /* end if */
      else {
          /* Point to local arrays */
          opt_stride = int_stride;
          opt_count = int_count;
          opt_block = int_block;
          for(u=0; u<space->extent.rank; u++) {
              /* contiguous hyperslabs have the block size equal to the stride */
              if(stride[u]==block[u]) {
                  int_count[u]=1;
                  int_stride[u]=1;
                  if(block[u]==1)
                      int_block[u]=count[u];
                  else
                      int_block[u]=block[u]*count[u];
              } /* end if */
              else {
                  if(count[u]==1)
                      int_stride[u]=1;
                  else {
                      HDassert(stride[u] > block[u]);
                      int_stride[u]=stride[u];
                  } /* end else */
                  int_count[u]=count[u];
                  int_block[u]=block[u];
              } /* end else */
          } /* end for */
      } /* end else */
  
      /* Fixup operation for non-hyperslab selections */
      switch(H5S_GET_SELECT_TYPE(space)) {
          case H5S_SEL_NONE:   /* No elements selected in dataspace */
              switch(op) {
                  case H5S_SELECT_SET:   /* Select "set" operation */
                      /* Change "none" selection to hyperslab selection */
                      break;
  
                  case H5S_SELECT_OR:    /* Binary "or" operation for hyperslabs */
                  case H5S_SELECT_XOR:   /* Binary "xor" operation for hyperslabs */
                  case H5S_SELECT_NOTA:  /* Binary "B not A" operation for hyperslabs */
                      op=H5S_SELECT_SET; /* Maps to "set" operation when applied to "none" selection */
                      break;
  
                  case H5S_SELECT_AND:   /* Binary "and" operation for hyperslabs */
                  case H5S_SELECT_NOTB:  /* Binary "A not B" operation for hyperslabs */
                      HGOTO_DONE(SUCCEED);        /* Selection stays "none" */
  
                  case H5S_SELECT_NOOP:
                  case H5S_SELECT_APPEND:
                  case H5S_SELECT_PREPEND:
                  case H5S_SELECT_INVALID:
                  default:
                      HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
              } /* end switch */
              break;
  
          case H5S_SEL_ALL:    /* All elements selected in dataspace */
              switch(op) {
                  case H5S_SELECT_SET:   /* Select "set" operation */
                      /* Change "all" selection to hyperslab selection */
                      break;
  
                  case H5S_SELECT_OR:    /* Binary "or" operation for hyperslabs */
                      HGOTO_DONE(SUCCEED);        /* Selection stays "all" */
  
                  case H5S_SELECT_AND:   /* Binary "and" operation for hyperslabs */
                      op=H5S_SELECT_SET; /* Maps to "set" operation when applied to "none" selection */
                      break;
  
                  case H5S_SELECT_XOR:   /* Binary "xor" operation for hyperslabs */
                  case H5S_SELECT_NOTB:  /* Binary "A not B" operation for hyperslabs */
                      /* Convert current "all" selection to "real" hyperslab selection */
                      /* Then allow operation to proceed */
                      {
                          hsize_t tmp_start[H5O_LAYOUT_NDIMS];   /* Temporary start information */
                          hsize_t tmp_stride[H5O_LAYOUT_NDIMS];   /* Temporary stride information */
                          hsize_t tmp_count[H5O_LAYOUT_NDIMS];    /* Temporary count information */
                          hsize_t tmp_block[H5O_LAYOUT_NDIMS];    /* Temporary block information */
  
                          /* Fill in temporary information for the dimensions */
                          for(u=0; u<space->extent.rank; u++) {
                              tmp_start[u]=0;
                              tmp_stride[u]=1;
                              tmp_count[u]=1;
                              tmp_block[u]=space->extent.size[u];
                          } /* end for */
  
                          /* Convert to hyperslab selection */
                          if(H5S_select_hyperslab(space,H5S_SELECT_SET,tmp_start,tmp_stride,tmp_count,tmp_block)<0)
                              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't convert selection")
                      } /* end case */
                      break;
  
                  case H5S_SELECT_NOTA:  /* Binary "B not A" operation for hyperslabs */
                      /* Convert to "none" selection */
                      if(H5S_select_none(space)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't convert selection")
                      HGOTO_DONE(SUCCEED);
  
                  case H5S_SELECT_NOOP:
                  case H5S_SELECT_APPEND:
                  case H5S_SELECT_PREPEND:
                  case H5S_SELECT_INVALID:
                  default:
                      HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
              } /* end switch */
              break;
  
          case H5S_SEL_HYPERSLABS:
              /* Hyperslab operation on hyperslab selection, OK */
              break;
  
          case H5S_SEL_POINTS: /* Can't combine hyperslab operations and point selections currently */
              if(op==H5S_SELECT_SET)      /* Allow only "set" operation to proceed */
                  break;
              /* Else fall through to error */
  
          case H5S_SEL_ERROR:
          case H5S_SEL_N:
          default:
              HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
      } /* end switch */
  
      if(op == H5S_SELECT_SET) {
          /* If we are setting a new selection, remove current selection first */
          if(H5S_SELECT_RELEASE(space) < 0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't release selection")
  
          /* Allocate space for the hyperslab selection information */
          if(NULL == (space->select.sel_info.hslab = H5FL_MALLOC(H5S_hyper_sel_t)))
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab info")
  
          /* Save the diminfo */
          space->select.num_elem = 1;
          for(u = 0; u < space->extent.rank; u++) {
              space->select.sel_info.hslab->app_diminfo[u].start = start[u];
              space->select.sel_info.hslab->app_diminfo[u].stride = stride[u];
              space->select.sel_info.hslab->app_diminfo[u].count = count[u];
              space->select.sel_info.hslab->app_diminfo[u].block = block[u];
  
              space->select.sel_info.hslab->opt_diminfo[u].start = start[u];
              space->select.sel_info.hslab->opt_diminfo[u].stride = opt_stride[u];
              space->select.sel_info.hslab->opt_diminfo[u].count = opt_count[u];
              space->select.sel_info.hslab->opt_diminfo[u].block = opt_block[u];
  
              space->select.num_elem *= (opt_count[u] * opt_block[u]);
          } /* end for */
  
          /* Indicate that the dimension information is valid */
          space->select.sel_info.hslab->diminfo_valid = TRUE;
  
          /* Indicate that there's no slab information */
          space->select.sel_info.hslab->span_lst = NULL;
      } /* end if */
      else if(op >= H5S_SELECT_OR && op <= H5S_SELECT_NOTA) {
          /* Sanity check */
          HDassert(H5S_GET_SELECT_TYPE(space) == H5S_SEL_HYPERSLABS);
  
          /* Check if there's no hyperslab span information currently */
          if(NULL == space->select.sel_info.hslab->span_lst)
              if(H5S_hyper_generate_spans(space) < 0)
                  HGOTO_ERROR(H5E_DATASPACE, H5E_UNINITIALIZED, FAIL, "dataspace does not have span tree")
  
          /* Indicate that the regular dimensions are no longer valid */
          space->select.sel_info.hslab->diminfo_valid = FALSE;
  
          /* Add in the new hyperslab information */
          if(H5S_generate_hyperslab(space, op, start, opt_stride, opt_count, opt_block) < 0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't generate hyperslabs")
      } /* end if */
      else
          HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
  
      /* Set selection type */
      space->select.type = H5S_sel_hyper;
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* end H5S_select_hyperslab() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5Sselect_hyperslab
   PURPOSE
      Specify a hyperslab to combine with the current hyperslab selection
   USAGE
      herr_t H5Sselect_hyperslab(dsid, op, start, stride, count, block)
          hid_t dsid;             IN: Dataspace ID of selection to modify
          H5S_seloper_t op;       IN: Operation to perform on current selection
          const hsize_t *start;        IN: Offset of start of hyperslab
          const hsize_t *stride;       IN: Hyperslab stride
          const hsize_t *count;        IN: Number of blocks included in hyperslab
          const hsize_t *block;        IN: Size of block in hyperslab
   RETURNS
      Non-negative on success/Negative on failure
   DESCRIPTION
      Combines a hyperslab selection with the current selection for a dataspace.
      If the current selection is not a hyperslab, it is freed and the hyperslab
      parameters passed in are combined with the H5S_SEL_ALL hyperslab (ie. a
      selection composing the entire current extent).  If STRIDE or BLOCK is
      NULL, they are assumed to be set to all '1'.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  herr_t
  H5Sselect_hyperslab(hid_t space_id, H5S_seloper_t op, const hsize_t start[],
           const hsize_t stride[], const hsize_t count[], const hsize_t block[])
  {
      H5S_t *space;               /* Dataspace to modify selection of */
      unsigned u;                 /* Local index variable */
      herr_t ret_value = SUCCEED; /* Return value */
  
      FUNC_ENTER_API(FAIL)
      H5TRACE6("e", "iSs*h*h*h*h", space_id, op, start, stride, count, block);
  
      /* Check args */
      if(NULL == (space = (H5S_t *)H5I_object_verify(space_id, H5I_DATASPACE)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space")
      if(H5S_SCALAR == H5S_GET_EXTENT_TYPE(space))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "hyperslab doesn't support H5S_SCALAR space")
      if(H5S_NULL == H5S_GET_EXTENT_TYPE(space))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "hyperslab doesn't support H5S_NULL space")
      if(start == NULL || count == NULL)
          HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "hyperslab not specified")
      if(!(op > H5S_SELECT_NOOP && op < H5S_SELECT_INVALID))
          HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
      if(stride!=NULL) {
          /* Check for 0-sized strides */
          for(u=0; u<space->extent.rank; u++) {
              if(stride[u]==0)
                  HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid stride==0 value")
          } /* end for */
      } /* end if */
  
      if (H5S_select_hyperslab(space, op, start, stride, count, block)<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to set hyperslab selection")
  
  done:
      FUNC_LEAVE_API(ret_value)
  } /* end H5Sselect_hyperslab() */
  #else /* NEW_HYPERSLAB_API */ /* Works */
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_operate_hyperslab
   *
   * Purpose:	Combines two hyperslabs with an operation, putting the
   *              result into a third hyperslab selection
   *
   * Return:	non-negative on success/NULL on failure
   *
   * Programmer:	Quincey Koziol
   *              Tuesday, October 30, 2001
   *
   * Modifications:
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_operate_hyperslab (H5S_t *result, H5S_hyper_span_info_t *spans1, H5S_seloper_t op, H5S_hyper_span_info_t *spans2,
      hbool_t can_own_span2, hbool_t *span2_owned)
  {
      H5S_hyper_span_info_t *a_not_b=NULL;    /* Span tree for hyperslab spans in old span tree and not in new span tree */
      H5S_hyper_span_info_t *a_and_b=NULL;    /* Span tree for hyperslab spans in both old and new span trees */
      H5S_hyper_span_info_t *b_not_a=NULL;    /* Span tree for hyperslab spans in new span tree and not in old span tree */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Check args */
      HDassert(result);
      HDassert(spans2);
      HDassert(op > H5S_SELECT_NOOP && op < H5S_SELECT_INVALID);
  
      /* Just copy the selection from spans2 if we are setting the selection */
      /* ('space1' to 'result' aliasing happens at the next layer up) */
      if(op==H5S_SELECT_SET) {
          if(H5S_hyper_merge_spans(result,spans2,can_own_span2)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
          /* Update the number of elements in current selection */
          result->select.num_elem=H5S_hyper_spans_nelem(spans2);
  
          /* Indicate that we took ownership of span2, if allowed */
          if(can_own_span2)
              *span2_owned=TRUE;
      } /* end if */
      else {
          hbool_t updated_spans = FALSE;  /* Whether the spans in the selection were modified */
  
          HDassert(spans1);
  
          /* Generate lists of spans which overlap and don't overlap */
          if(H5S_hyper_clip_spans(spans1,spans2,&a_not_b,&a_and_b,&b_not_a)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't clip hyperslab information")
  
          /* Switch on the operation */
          switch(op) {
              case H5S_SELECT_OR:
                  /* Copy spans from spans1 to current selection */
                  if(spans1!=NULL) {
                      if(H5S_hyper_merge_spans(result,spans1,FALSE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      result->select.num_elem=H5S_hyper_spans_nelem(spans1);
                  } /* end if */
  
                  /* Add any new spans from spans2 to current selection */
                  if(b_not_a!=NULL) {
                      if(H5S_hyper_merge_spans(result,b_not_a,FALSE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      result->select.num_elem+=H5S_hyper_spans_nelem(b_not_a);
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  break;
  
              case H5S_SELECT_AND:
                  /* Check if there are any overlapped selections */
                  if(a_and_b!=NULL) {
                      if(H5S_hyper_merge_spans(result,a_and_b,TRUE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      result->select.num_elem=H5S_hyper_spans_nelem(a_and_b);
  
                      /* Indicate that the result owns the a_and_b spans */
                      a_and_b=NULL;
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  break;
  
              case H5S_SELECT_XOR:
                  /* Check if there are any non-overlapped selections */
                  if(a_not_b!=NULL) {
                      if(H5S_hyper_merge_spans(result,a_not_b,FALSE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      result->select.num_elem=H5S_hyper_spans_nelem(a_not_b);
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  if(b_not_a!=NULL) {
                      if(H5S_hyper_merge_spans(result,b_not_a,FALSE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      result->select.num_elem+=H5S_hyper_spans_nelem(b_not_a);
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  break;
  
              case H5S_SELECT_NOTB:
                  /* Check if there are any non-overlapped selections */
                  if(a_not_b!=NULL) {
                      if(H5S_hyper_merge_spans(result,a_not_b,TRUE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      result->select.num_elem=H5S_hyper_spans_nelem(a_not_b);
  
                      /* Indicate that the result owns the a_not_b spans */
                      a_not_b=NULL;
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  break;
  
              case H5S_SELECT_NOTA:
                  /* Check if there are any non-overlapped selections */
                  if(b_not_a!=NULL) {
                      if(H5S_hyper_merge_spans(result,b_not_a,TRUE)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't insert hyperslabs")
  
                      /* Update the number of elements in current selection */
                      result->select.num_elem=H5S_hyper_spans_nelem(b_not_a);
  
                      /* Indicate that the result owns the b_not_a spans */
                      b_not_a=NULL;
  
                      /* Indicate that the spans were updated */
                      updated_spans = TRUE;
                  } /* end if */
                  break;
  
              default:
                  HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
          } /* end switch */
  
          /* Free the hyperslab trees generated from the clipping algorithm */
          if(a_not_b)
              H5S_hyper_free_span_info(a_not_b);
          if(a_and_b)
              H5S_hyper_free_span_info(a_and_b);
          if(b_not_a)
              H5S_hyper_free_span_info(b_not_a);
  
          /* Check if the resulting hyperslab span tree is empty */
          if(result->select.sel_info.hslab->span_lst==NULL) {
              H5S_hyper_span_info_t *spans;     /* Empty hyperslab span tree */
  
              /* Sanity check */
              HDassert(result->select.num_elem == 0);
  
              /* Allocate a span info node */
              if((spans = H5FL_MALLOC(H5S_hyper_span_info_t))==NULL)
                  HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span")
  
              /* Set the reference count */
              spans->count=1;
  
              /* Reset the scratch pad space */
              spans->scratch=0;
  
              /* Set to empty tree */
              spans->head=NULL;
  
              /* Set pointer to empty span tree */
              result->select.sel_info.hslab->span_lst=spans;
          } /* end if */
          else {
              /* Check if we updated the spans */
              if(updated_spans) {
                  /* Attempt to rebuild "optimized" start/stride/count/block information.
                   * from resulting hyperslab span tree
                   */
                  if(H5S_hyper_rebuild(result) < 0)
                      HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOUNT, FAIL, "can't rebuild hyperslab info")
              } /* end if */
          } /* end else */
      } /* end else */
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* end H5S_operate_hyperslab() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_generate_hyperlab
   *
   * Purpose:	Generate hyperslab information from H5S_select_hyperslab()
   *
   * Return:	Non-negative on success/Negative on failure
   *
   * Programmer:	Quincey Koziol (split from HS_select_hyperslab()).
   *              Tuesday, September 12, 2000
   *
   * Modifications:
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_generate_hyperslab (H5S_t *space, H5S_seloper_t op,
  		      const hsize_t start[],
  		      const hsize_t stride[],
  		      const hsize_t count[],
  		      const hsize_t block[])
  {
      H5S_hyper_span_info_t *new_spans=NULL;   /* Span tree for new hyperslab */
      H5S_hyper_span_info_t *tmp_spans=NULL;   /* Temporary copy of selection */
      hbool_t span2_owned=FALSE;          /* Flag to indicate that span2 was used in H5S_operate_hyperslab() */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Check args */
      HDassert(space);
      HDassert(op > H5S_SELECT_NOOP && op < H5S_SELECT_INVALID);
      HDassert(start);
      HDassert(stride);
      HDassert(count);
      HDassert(block);
  
      /* Generate span tree for new hyperslab information */
      if((new_spans=H5S_hyper_make_spans(space->extent.rank,start,stride,count,block))==NULL)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't create hyperslab information")
  
      /* Copy the original dataspace */
      if(space->select.sel_info.hslab->span_lst!=NULL) {
          /* Take ownership of the dataspace's hyperslab spans */
          /* (These are freed later) */
          tmp_spans=space->select.sel_info.hslab->span_lst;
          space->select.sel_info.hslab->span_lst=NULL;
  
          /* Reset the other dataspace selection information */
          if(H5S_SELECT_RELEASE(space)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't release selection")
  
          /* Allocate space for the hyperslab selection information */
          if((space->select.sel_info.hslab=H5FL_MALLOC(H5S_hyper_sel_t))==NULL)
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab info")
      } /* end if */
  
      /* Combine tmp_space (really space) & new_space, with the result in space */
      if(H5S_operate_hyperslab(space,tmp_spans,op,new_spans,TRUE,&span2_owned)<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't clip hyperslab information")
  
  done:
      /* Free temporary data structures */
      if(tmp_spans!=NULL)
          if(H5S_hyper_free_span_info(tmp_spans)<0)
              HDONE_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release temporary hyperslab spans")
      if(new_spans!=NULL && span2_owned==FALSE)
          if(H5S_hyper_free_span_info(new_spans)<0)
              HDONE_ERROR(H5E_INTERNAL, H5E_CANTFREE, FAIL, "failed to release temporary hyperslab spans")
  
      FUNC_LEAVE_NOAPI(ret_value)
  } /* end H5S_generate_hyperslab() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_select_hyperslab
   *
   * Purpose:	Internal version of H5Sselect_hyperslab().
   *
   * Return:	Non-negative on success/Negative on failure
   *
   * Programmer:	Quincey Koziol
   *              Wednesday, January 10, 2001
   *
   * Modifications:
   *
   *-------------------------------------------------------------------------
   */
  herr_t
  H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op,
  		      const hsize_t start[],
  		      const hsize_t *stride,
  		      const hsize_t count[],
  		      const hsize_t *block)
  {
      hsize_t int_stride[H5O_LAYOUT_NDIMS];   /* Internal storage for stride information */
      hsize_t int_count[H5O_LAYOUT_NDIMS];    /* Internal storage for count information */
      hsize_t int_block[H5O_LAYOUT_NDIMS];    /* Internal storage for block information */
      const hsize_t *opt_stride;      /* Optimized stride information */
      const hsize_t *opt_count;       /* Optimized count information */
      const hsize_t *opt_block;       /* Optimized block information */
      unsigned u;                    /* Counters */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI(FAIL)
  
      /* Check args */
      HDassert(space);
      HDassert(start);
      HDassert(count);
      HDassert(op > H5S_SELECT_NOOP && op < H5S_SELECT_INVALID);
  
      /* Point to the correct stride values */
      if(stride==NULL)
          stride = _ones;
  
      /* Point to the correct block values */
      if(block==NULL)
          block = _ones;
  
      /*
       * Check new selection.
       */
      for(u=0; u<space->extent.rank; u++) {
          /* Check for overlapping hyperslab blocks in new selection. */
          if(count[u]>1 && stride[u]<block[u])
              HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "hyperslab blocks overlap")
  
          /* Detect zero-sized hyperslabs in new selection */
          if(count[u] == 0 || block[u] == 0) {
              switch(op) {
                  case H5S_SELECT_SET:   /* Select "set" operation */
                  case H5S_SELECT_AND:   /* Binary "and" operation for hyperslabs */
                  case H5S_SELECT_NOTA:  /* Binary "B not A" operation for hyperslabs */
                      /* Convert to "none" selection */
                      if(H5S_select_none(space)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't convert selection")
                      HGOTO_DONE(SUCCEED);
  
                  case H5S_SELECT_OR:    /* Binary "or" operation for hyperslabs */
                  case H5S_SELECT_XOR:   /* Binary "xor" operation for hyperslabs */
                  case H5S_SELECT_NOTB:  /* Binary "A not B" operation for hyperslabs */
                      HGOTO_DONE(SUCCEED);        /* Selection stays same */
  
                  default:
                      HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
              } /* end switch */
          } /* end if */
      } /* end for */
  
      /* Optimize hyperslab parameters to merge contiguous blocks, etc. */
      if(stride == _ones && block == _ones) {
          /* Point to existing arrays */
          opt_stride = _ones;
          opt_count = _ones;
          opt_block = count;
      } /* end if */
      else {
          /* Point to local arrays */
          opt_stride = int_stride;
          opt_count = int_count;
          opt_block = int_block;
          for(u=0; u<space->extent.rank; u++) {
              /* contiguous hyperslabs have the block size equal to the stride */
              if(stride[u]==block[u]) {
                  int_count[u]=1;
                  int_stride[u]=1;
                  if(block[u]==1)
                      int_block[u]=count[u];
                  else
                      int_block[u]=block[u]*count[u];
              } /* end if */
              else {
                  if(count[u]==1)
                      int_stride[u]=1;
                  else {
                      HDassert(stride[u] > block[u]);
                      int_stride[u]=stride[u];
                  } /* end else */
                  int_count[u]=count[u];
                  int_block[u]=block[u];
              } /* end else */
          } /* end for */
      } /* end else */
  
      /* Fixup operation for non-hyperslab selections */
      switch(H5S_GET_SELECT_TYPE(space)) {
          case H5S_SEL_NONE:   /* No elements selected in dataspace */
              switch(op) {
                  case H5S_SELECT_SET:   /* Select "set" operation */
                      /* Change "none" selection to hyperslab selection */
                      break;
  
                  case H5S_SELECT_OR:    /* Binary "or" operation for hyperslabs */
                  case H5S_SELECT_XOR:   /* Binary "xor" operation for hyperslabs */
                  case H5S_SELECT_NOTA:  /* Binary "B not A" operation for hyperslabs */
                      op=H5S_SELECT_SET; /* Maps to "set" operation when applied to "none" selection */
                      break;
  
                  case H5S_SELECT_AND:   /* Binary "and" operation for hyperslabs */
                  case H5S_SELECT_NOTB:  /* Binary "A not B" operation for hyperslabs */
                      HGOTO_DONE(SUCCEED);        /* Selection stays "none" */
  
                  default:
                      HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
              } /* end switch */
              break;
  
          case H5S_SEL_ALL:    /* All elements selected in dataspace */
              switch(op) {
                  case H5S_SELECT_SET:   /* Select "set" operation */
                      /* Change "all" selection to hyperslab selection */
                      break;
  
                  case H5S_SELECT_OR:    /* Binary "or" operation for hyperslabs */
                      HGOTO_DONE(SUCCEED);        /* Selection stays "all" */
  
                  case H5S_SELECT_AND:   /* Binary "and" operation for hyperslabs */
                      op=H5S_SELECT_SET; /* Maps to "set" operation when applied to "none" selection */
                      break;
  
                  case H5S_SELECT_XOR:   /* Binary "xor" operation for hyperslabs */
                  case H5S_SELECT_NOTB:  /* Binary "A not B" operation for hyperslabs */
                      /* Convert current "all" selection to "real" hyperslab selection */
                      /* Then allow operation to proceed */
                      {
                          hsize_t tmp_start[H5O_LAYOUT_NDIMS];   /* Temporary start information */
                          hsize_t tmp_stride[H5O_LAYOUT_NDIMS];   /* Temporary stride information */
                          hsize_t tmp_count[H5O_LAYOUT_NDIMS];    /* Temporary count information */
                          hsize_t tmp_block[H5O_LAYOUT_NDIMS];    /* Temporary block information */
  
                          /* Fill in temporary information for the dimensions */
                          for(u=0; u<space->extent.rank; u++) {
                              tmp_start[u]=0;
                              tmp_stride[u]=1;
                              tmp_count[u]=1;
                              tmp_block[u]=space->extent.size[u];
                          } /* end for */
  
                          /* Convert to hyperslab selection */
                          if(H5S_select_hyperslab(space,H5S_SELECT_SET,tmp_start,tmp_stride,tmp_count,tmp_block)<0)
                              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't convert selection")
                      } /* end case */
                      break;
  
                  case H5S_SELECT_NOTA:  /* Binary "B not A" operation for hyperslabs */
                      /* Convert to "none" selection */
                      if(H5S_select_none(space)<0)
                          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't convert selection")
                      HGOTO_DONE(SUCCEED);
  
                  default:
                      HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
              } /* end switch */
              break;
  
          case H5S_SEL_HYPERSLABS:
              /* Hyperslab operation on hyperslab selection, OK */
              break;
  
          case H5S_SEL_POINTS: /* Can't combine hyperslab operations and point selections currently */
              if(op==H5S_SELECT_SET)      /* Allow only "set" operation to proceed */
                  break;
              /* Else fall through to error */
  
          default:
              HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
      } /* end switch */
  
  
      if(op==H5S_SELECT_SET) {
          /* If we are setting a new selection, remove current selection first */
          if(H5S_SELECT_RELEASE(space)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't release hyperslab")
  
          /* Allocate space for the hyperslab selection information */
          if((space->select.sel_info.hslab=H5FL_MALLOC(H5S_hyper_sel_t))==NULL)
              HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab info")
  
          /* Save the diminfo */
          space->select.num_elem=1;
          for(u=0; u<space->extent.rank; u++) {
              space->select.sel_info.hslab->app_diminfo[u].start = start[u];
              space->select.sel_info.hslab->app_diminfo[u].stride = stride[u];
              space->select.sel_info.hslab->app_diminfo[u].count = count[u];
              space->select.sel_info.hslab->app_diminfo[u].block = block[u];
  
              space->select.sel_info.hslab->opt_diminfo[u].start = start[u];
              space->select.sel_info.hslab->opt_diminfo[u].stride = opt_stride[u];
              space->select.sel_info.hslab->opt_diminfo[u].count = opt_count[u];
              space->select.sel_info.hslab->opt_diminfo[u].block = opt_block[u];
  
              space->select.num_elem*=(opt_count[u]*opt_block[u]);
          } /* end for */
  
          /* Indicate that the dimension information is valid */
          space->select.sel_info.hslab->diminfo_valid=TRUE;
  
          /* Indicate that there's no slab information */
          space->select.sel_info.hslab->span_lst=NULL;
      } /* end if */
      else if(op>=H5S_SELECT_OR && op<=H5S_SELECT_NOTA) {
          /* Sanity check */
          HDassert(H5S_GET_SELECT_TYPE(space) == H5S_SEL_HYPERSLABS);
  
          /* Check if there's no hyperslab span information currently */
          if(space->select.sel_info.hslab->span_lst==NULL)
              if(H5S_hyper_generate_spans(space)<0)
                  HGOTO_ERROR(H5E_DATASPACE, H5E_UNINITIALIZED, FAIL, "dataspace does not have span tree")
  
          /* Add in the new hyperslab information */
          if(H5S_generate_hyperslab (space, op, start, opt_stride, opt_count, opt_block)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINSERT, FAIL, "can't generate hyperslabs")
  
          /* Indicate that the regular dimensions are no longer valid */
          space->select.sel_info.hslab->diminfo_valid=FALSE;
      } /* end if */
      else
          HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
  
      /* Set selection type */
      space->select.type=H5S_sel_hyper;
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* end H5S_select_hyperslab() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5Sselect_hyperslab
   PURPOSE
      Specify a hyperslab to combine with the current hyperslab selection
   USAGE
      herr_t H5Sselect_hyperslab(dsid, op, start, stride, count, block)
          hid_t dsid;             IN: Dataspace ID of selection to modify
          H5S_seloper_t op;       IN: Operation to perform on current selection
          const hsize_t *start;        IN: Offset of start of hyperslab
          const hsize_t *stride;       IN: Hyperslab stride
          const hsize_t *count;        IN: Number of blocks included in hyperslab
          const hsize_t *block;        IN: Size of block in hyperslab
   RETURNS
      Non-negative on success/Negative on failure
   DESCRIPTION
      Combines a hyperslab selection with the current selection for a dataspace.
      If the current selection is not a hyperslab, it is freed and the hyperslab
      parameters passed in are combined with the H5S_SEL_ALL hyperslab (ie. a
      selection composing the entire current extent).  If STRIDE or BLOCK is
      NULL, they are assumed to be set to all '1'.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  herr_t
  H5Sselect_hyperslab(hid_t space_id, H5S_seloper_t op, const hsize_t start[],
           const hsize_t stride[], const hsize_t count[], const hsize_t block[])
  {
      H5S_t	*space = NULL;  /* Dataspace to modify selection of */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_API(FAIL)
      H5TRACE6("e", "iSs*h*h*h*h", space_id, op, start, stride, count, block);
  
      /* Check args */
      if (NULL == (space=H5I_object_verify(space_id, H5I_DATASPACE)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space")
      if (H5S_SCALAR==H5S_GET_EXTENT_TYPE(space))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "hyperslab doesn't support H5S_SCALAR space")
      if (H5S_NULL==H5S_GET_EXTENT_TYPE(space))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "hyperslab doesn't support H5S_NULL space")
      if(start==NULL || count==NULL)
          HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "hyperslab not specified")
      if(!(op>H5S_SELECT_NOOP && op<H5S_SELECT_INVALID))
          HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
      if(stride!=NULL) {
          unsigned u;             /* Local index variable */
  
          /* Check for 0-sized strides */
          for(u=0; u<space->extent.rank; u++) {
              if(stride[u]==0)
                  HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid stride==0 value")
          } /* end for */
      } /* end if */
  
      if (H5S_select_hyperslab(space, op, start, stride, count, block)<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to set hyperslab selection")
  
  done:
      FUNC_LEAVE_API(ret_value)
  } /* end H5Sselect_hyperslab() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5Scombine_hyperslab
   PURPOSE
      Specify a hyperslab to combine with the current hyperslab selection and
      return a new dataspace with the combined selection as the selection in the
      new dataspace.
   USAGE
      hid_t H5Srefine_hyperslab(dsid, op, start, stride, count, block)
          hid_t dsid;             IN: Dataspace ID of selection to use
          H5S_seloper_t op;       IN: Operation to perform on current selection
          const hsize_t *start;        IN: Offset of start of hyperslab
          const hsize_t *stride;       IN: Hyperslab stride
          const hsize_t *count;        IN: Number of blocks included in hyperslab
          const hsize_t *block;        IN: Size of block in hyperslab
   RETURNS
      Dataspace ID on success/Negative on failure
   DESCRIPTION
      Combines a hyperslab selection with the current selection for a dataspace,
      creating a new dataspace to return the generated selection.
      If the current selection is not a hyperslab, it is freed and the hyperslab
      parameters passed in are combined with the H5S_SEL_ALL hyperslab (ie. a
      selection composing the entire current extent).  If STRIDE or BLOCK is
      NULL, they are assumed to be set to all '1'.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  hid_t
  H5Scombine_hyperslab(hid_t space_id, H5S_seloper_t op, const hsize_t start[],
           const hsize_t stride[], const hsize_t count[], const hsize_t block[])
  {
      H5S_t	*space = NULL;  /* Dataspace to modify selection of */
      H5S_t	*new_space = NULL;  /* New dataspace created */
      hid_t	ret_value;
  
      FUNC_ENTER_API(FAIL)
      H5TRACE6("i", "iSs*h*h*h*h", space_id, op, start, stride, count, block);
  
      /* Check args */
      if (NULL == (space=H5I_object_verify(space_id, H5I_DATASPACE)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space")
      if(start==NULL || count==NULL)
          HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "hyperslab not specified")
  
      if(!(op>H5S_SELECT_NOOP && op<H5S_SELECT_INVALID))
          HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
  
      /* Copy the first dataspace */
      if (NULL == (new_space = H5S_copy (space, TRUE, TRUE)))
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, NULL, "unable to copy data space")
  
      /* Go modify the selection in the new dataspace */
      if (H5S_select_hyperslab(new_space, op, start, stride, count, block)<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to set hyperslab selection")
  
      /* Atomize */
      if ((ret_value=H5I_register (H5I_DATASPACE, new_space, TRUE))<0)
          HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register dataspace atom")
  
  done:
      if (ret_value<0 && new_space)
          H5S_close(new_space);
  
      FUNC_LEAVE_API(ret_value)
  } /* end H5Scombine_hyperslab() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_combine_select
   *
   * Purpose:	Internal version of H5Scombine_select().
   *
   * Return:	New dataspace on success/NULL on failure
   *
   * Programmer:	Quincey Koziol
   *              Tuesday, October 30, 2001
   *
   * Modifications:
   *
   *-------------------------------------------------------------------------
   */
  static H5S_t *
  H5S_combine_select (H5S_t *space1, H5S_seloper_t op, H5S_t *space2)
  {
      H5S_t *new_space=NULL;    /* New dataspace generated */
      hbool_t span2_owned=FALSE;          /* Flag to indicate that span2 was used in H5S_operate_hyperslab() */
      H5S_t *ret_value;         /* return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Check args */
      HDassert(space1);
      HDassert(space2);
      HDassert(op > H5S_SELECT_NOOP && op < H5S_SELECT_INVALID);
  
      /* Check that the space selections both have span trees */
      if(space1->select.sel_info.hslab->span_lst==NULL)
          if(H5S_hyper_generate_spans(space1)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_UNINITIALIZED, NULL, "dataspace does not have span tree")
      if(space2->select.sel_info.hslab->span_lst==NULL)
          if(H5S_hyper_generate_spans(space2)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_UNINITIALIZED, NULL, "dataspace does not have span tree")
  
      /* Copy the first dataspace */
      if (NULL == (new_space = H5S_copy (space1, TRUE, TRUE)))
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, NULL, "unable to copy data space")
  
      /* Free the current selection for the new dataspace */
      if(H5S_SELECT_RELEASE(new_space)<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, NULL, "can't release selection")
  
      /* Allocate space for the hyperslab selection information */
      if((new_space->select.sel_info.hslab=H5FL_CALLOC(H5S_hyper_sel_t))==NULL)
          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab info")
  
      /* Combine space1 & space2, with the result in new_space */
      if(H5S_operate_hyperslab(new_space,space1->select.sel_info.hslab->span_lst,op,space2->select.sel_info.hslab->span_lst,FALSE,&span2_owned)<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, NULL, "can't clip hyperslab information")
  
      /* Set return value */
      ret_value=new_space;
  
  done:
      if(ret_value==NULL && new_space!=NULL)
          H5S_close(new_space);
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* end H5S_combine_select() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5Scombine_select
   PURPOSE
      Combine two hyperslab selections with an operation, returning a dataspace
      with the resulting selection.
   USAGE
      hid_t H5Scombine_select(space1, op, space2)
          hid_t space1;           IN: First Dataspace ID
          H5S_seloper_t op;       IN: Selection operation
          hid_t space2;           IN: Second Dataspace ID
   RETURNS
      Dataspace ID on success/Negative on failure
   DESCRIPTION
      Combine two existing hyperslab selections with an operation, returning
      a new dataspace with the resulting selection.  The dataspace extent from
      space1 is copied for the dataspace extent of the newly created dataspace.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  hid_t
  H5Scombine_select(hid_t space1_id, H5S_seloper_t op, hid_t space2_id)
  {
      H5S_t	*space1;                /* First Dataspace */
      H5S_t	*space2;                /* Second Dataspace */
      H5S_t	*new_space = NULL;      /* New Dataspace */
      hid_t	ret_value;
  
      FUNC_ENTER_API(FAIL)
      H5TRACE3("i", "iSsi", space1_id, op, space2_id);
  
      /* Check args */
      if (NULL == (space1=H5I_object_verify(space1_id, H5I_DATASPACE)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space")
      if (NULL == (space2=H5I_object_verify(space2_id, H5I_DATASPACE)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space")
      if(!(op>H5S_SELECT_NOOP && op<H5S_SELECT_INVALID))
          HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
  
      /* Check that both dataspaces have the same rank */
      if(space1->extent.rank!=space2->extent.rank)
          HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "dataspaces not same rank")
  
      /* Check that both dataspaces have hyperslab selections */
      if(H5S_GET_SELECT_TYPE(space1)!=H5S_SEL_HYPERSLABS || H5S_GET_SELECT_TYPE(space2)!=H5S_SEL_HYPERSLABS)
          HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "dataspaces don't have hyperslab selections")
  
      /* Go combine the dataspaces */
      if ((new_space=H5S_combine_select(space1, op, space2))==NULL)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to create hyperslab selection")
  
      /* Atomize */
      if ((ret_value=H5I_register (H5I_DATASPACE, new_space, TRUE))<0)
          HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register dataspace atom")
  
  done:
      if (ret_value<0 && new_space)
          H5S_close(new_space);
  
      FUNC_LEAVE_API(ret_value)
  } /* end H5Scombine_select() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5S_select_select
   *
   * Purpose:	Internal version of H5Sselect_select().
   *
   * Return:	New dataspace on success/NULL on failure
   *
   * Programmer:	Quincey Koziol
   *              Tuesday, October 30, 2001
   *
   * Modifications:
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5S_select_select (H5S_t *space1, H5S_seloper_t op, H5S_t *space2)
  {
      H5S_hyper_span_info_t *tmp_spans=NULL;   /* Temporary copy of selection */
      hbool_t span2_owned=FALSE;          /* Flag to indicate that span2 was used in H5S_operate_hyperslab() */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI_NOINIT
  
      /* Check args */
      HDassert(space1);
      HDassert(space2);
      HDassert(op > H5S_SELECT_NOOP && op < H5S_SELECT_INVALID);
  
      /* Check that the space selections both have span trees */
      if(space1->select.sel_info.hslab->span_lst==NULL)
          if(H5S_hyper_generate_spans(space1)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_UNINITIALIZED, FAIL, "dataspace does not have span tree")
      if(space2->select.sel_info.hslab->span_lst==NULL)
          if(H5S_hyper_generate_spans(space2)<0)
              HGOTO_ERROR(H5E_DATASPACE, H5E_UNINITIALIZED, FAIL, "dataspace does not have span tree")
  
      /* Take ownership of the dataspace's hyperslab spans */
      /* (These are freed later) */
      tmp_spans=space1->select.sel_info.hslab->span_lst;
      space1->select.sel_info.hslab->span_lst=NULL;
  
      /* Reset the other dataspace selection information */
      if(H5S_SELECT_RELEASE(space1)<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't release selection")
  
      /* Allocate space for the hyperslab selection information */
      if((space1->select.sel_info.hslab=H5FL_CALLOC(H5S_hyper_sel_t))==NULL)
          HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab info")
  
      /* Combine tmp_spans (from space1) & spans from space2, with the result in space1 */
      if(H5S_operate_hyperslab(space1,tmp_spans,op,space2->select.sel_info.hslab->span_lst,FALSE,&span2_owned)<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCLIP, FAIL, "can't clip hyperslab information")
  
  done:
      if(tmp_spans!=NULL)
          H5S_hyper_free_span_info(tmp_spans);
  
      FUNC_LEAVE_NOAPI(ret_value)
  }   /* end H5S_select_select() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5Sselect_select
   PURPOSE
      Refine a hyperslab selection with an operation using a second hyperslab
      to modify it.
   USAGE
      herr_t H5Sselect_select(space1, op, space2)
          hid_t space1;           IN/OUT: First Dataspace ID
          H5S_seloper_t op;       IN: Selection operation
          hid_t space2;           IN: Second Dataspace ID
   RETURNS
      Non-negative on success/Negative on failure
   DESCRIPTION
      Refine an existing hyperslab selection with an operation, using a second
      hyperslab.  The first selection is modified to contain the result of
      space1 operated on by space2.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  herr_t
  H5Sselect_select(hid_t space1_id, H5S_seloper_t op, hid_t space2_id)
  {
      H5S_t	*space1;                /* First Dataspace */
      H5S_t	*space2;                /* Second Dataspace */
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_API(FAIL)
      H5TRACE3("e", "iSsi", space1_id, op, space2_id);
  
      /* Check args */
      if (NULL == (space1=H5I_object_verify(space1_id, H5I_DATASPACE)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space")
      if (NULL == (space2=H5I_object_verify(space2_id, H5I_DATASPACE)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space")
      if(!(op>H5S_SELECT_NOOP && op<H5S_SELECT_INVALID))
          HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "invalid selection operation")
  
      /* Check that both dataspaces have the same rank */
      if(space1->extent.rank!=space2->extent.rank)
          HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "dataspaces not same rank")
  
      /* Check that both dataspaces have hyperslab selections */
      if(H5S_GET_SELECT_TYPE(space1)!=H5S_SEL_HYPERSLABS || H5S_GET_SELECT_TYPE(space2)!=H5S_SEL_HYPERSLABS)
          HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "dataspaces don't have hyperslab selections")
  
      /* Go refine the first selection */
      if (H5S_select_select(space1, op, space2)<0)
          HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to modify hyperslab selection")
  
  done:
      FUNC_LEAVE_API(ret_value)
  } /* end H5Sselect_select() */
  #endif /* NEW_HYPERSLAB_API */ /* Works */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_get_seq_list_gen
   PURPOSE
      Create a list of offsets & lengths for a selection
   USAGE
      herr_t H5S_select_hyper_get_file_list_gen(space,iter,maxseq,maxelem,nseq,nelem,off,len)
          H5S_t *space;           IN: Dataspace containing selection to use.
          H5S_sel_iter_t *iter;   IN/OUT: Selection iterator describing last
                                      position of interest in selection.
          size_t maxseq;          IN: Maximum number of sequences to generate
          size_t maxelem;         IN: Maximum number of elements to include in the
                                      generated sequences
          size_t *nseq;           OUT: Actual number of sequences generated
          size_t *nelem;          OUT: Actual number of elements in sequences generated
          hsize_t *off;           OUT: Array of offsets
          size_t *len;            OUT: Array of lengths
   RETURNS
      Non-negative on success/Negative on failure.
   DESCRIPTION
      Use the selection in the dataspace to generate a list of byte offsets and
      lengths for the region(s) selected.  Start/Restart from the position in the
      ITER parameter.  The number of sequences generated is limited by the MAXSEQ
      parameter and the number of sequences actually generated is stored in the
      NSEQ parameter.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_get_seq_list_gen(const H5S_t *space,H5S_sel_iter_t *iter,
      size_t maxseq, size_t maxelem, size_t *nseq, size_t *nelem,
      hsize_t *off, size_t *len)
  {
      H5S_hyper_span_t *curr_span;    /* Current hyperslab span node */
      H5S_hyper_span_t **ispan;       /* Iterator's hyperslab span nodes */
      hsize_t slab[H5O_LAYOUT_NDIMS]; /* Cumulative size of each dimension in bytes */
      hsize_t acc;       /* Accumulator for computing cumulative sizes */
      hsize_t loc_off;   /* Element offset in the dataspace */
      hsize_t last_span_end = 0; /* The offset of the end of the last span */
      hsize_t *abs_arr;  /* Absolute hyperslab span position */
      const hssize_t *off_arr;  /* Offset within the dataspace extent */
      size_t span_size = 0; /* Number of bytes in current span to actually process */
      size_t io_left;    /* Number of elements left to process */
      size_t io_bytes_left;   /* Number of bytes left to process */
      size_t io_used;    /* Number of elements processed */
      size_t curr_seq = 0; /* Number of sequence/offsets stored in the arrays */
      size_t elem_size;  /* Size of each element iterating over */
      unsigned ndims;    /* Number of dimensions of dataset */
      unsigned fast_dim; /* Rank of the fastest changing dimension for the dataspace */
      int curr_dim;      /* Current dimension being operated on */
      unsigned u;        /* Index variable */
      int i;             /* Index variable */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(space);
      HDassert(iter);
      HDassert(maxseq > 0);
      HDassert(maxelem > 0);
      HDassert(nseq);
      HDassert(nelem);
      HDassert(off);
      HDassert(len);
  
      /* Set the rank of the fastest changing dimension */
      ndims = space->extent.rank;
      fast_dim = (ndims - 1);
  
      /* Get the pointers to the current span info and span nodes */
      curr_span = iter->u.hyp.span[fast_dim];
      abs_arr = iter->u.hyp.off;
      off_arr = space->select.offset;
      ispan = iter->u.hyp.span;
      elem_size = iter->elmt_size;
  
      /* Set the amount of elements to perform I/O on, etc. */
      H5_CHECK_OVERFLOW(iter->elmt_left, hsize_t, size_t);
      io_left = MIN(maxelem, (size_t)iter->elmt_left);
      io_bytes_left = io_left * elem_size;
  
      /* Compute the cumulative size of dataspace dimensions */
      for(i = (int)fast_dim, acc = elem_size; i >= 0; i--) {
          slab[i] = acc;
          acc *= space->extent.size[i];
      } /* end for */
  
      /* Set the offset of the first element iterated on */
      for(u = 0, loc_off = 0; u < ndims; u++)
          /* Compute the sequential element offset */
          loc_off += ((hsize_t)((hssize_t)abs_arr[u] + off_arr[u])) * slab[u];
  
      /* Range check against number of elements left in selection */
      HDassert(io_bytes_left <= (iter->elmt_left * elem_size));
  
      /* Take care of any partial spans leftover from previous I/Os */
      if(abs_arr[fast_dim]!=curr_span->low) {
  
          /* Finish the span in the fastest changing dimension */
  
          /* Compute the number of bytes to attempt in this span */
          H5_CHECKED_ASSIGN(span_size, size_t, ((curr_span->high-abs_arr[fast_dim])+1)*elem_size, hsize_t);
  
          /* Check number of bytes against upper bounds allowed */
          if(span_size>io_bytes_left)
              span_size=io_bytes_left;
  
          /* Add the partial span to the list of sequences */
          off[curr_seq]=loc_off;
          len[curr_seq]=span_size;
  
          /* Increment sequence count */
          curr_seq++;
  
          /* Set the location of the last span's end */
          last_span_end=loc_off+span_size;
  
          /* Decrement I/O left to perform */
          io_bytes_left-=span_size;
  
          /* Advance the hyperslab iterator */
          /* Check if we are done */
          if(io_bytes_left > 0) {
              /* Move to next span in fastest changing dimension */
              curr_span = curr_span->next;
  
              if(NULL != curr_span) {
                  /* Move location offset of destination */
                  loc_off += (curr_span->low - abs_arr[fast_dim]) * elem_size;
  
                  /* Move iterator for fastest changing dimension */
                  abs_arr[fast_dim] = curr_span->low;
              } /* end if */
          } /* end if */
          else {
              abs_arr[fast_dim] += span_size / elem_size;
  
              /* Check if we are still within the span */
              if(abs_arr[fast_dim] <= curr_span->high) {
                  iter->u.hyp.span[fast_dim] = curr_span;
              } /* end if */
              /* If we walked off that span, advance to the next span */
              else {
                  /* Advance span in this dimension */
                  curr_span = curr_span->next;
  
                  /* Check if we have a valid span in this dimension still */
                  if(NULL != curr_span) {
                      /* Reset absolute position */
                      abs_arr[fast_dim] = curr_span->low;
                      iter->u.hyp.span[fast_dim] = curr_span;
                  } /* end if */
              } /* end else */
          } /* end else */
  
          /* Adjust iterator pointers */
  
          if(NULL == curr_span) {
  /* Same as code in main loop */
              /* Start at the next fastest dim */
              curr_dim = (int)(fast_dim - 1);
  
              /* Work back up through the dimensions */
              while(curr_dim >= 0) {
                  /* Reset the current span */
                  curr_span = iter->u.hyp.span[curr_dim];
  
                  /* Increment absolute position */
                  abs_arr[curr_dim]++;
  
                  /* Check if we are still within the span */
                  if(abs_arr[curr_dim] <= curr_span->high) {
                      break;
                  } /* end if */
                  /* If we walked off that span, advance to the next span */
                  else {
                      /* Advance span in this dimension */
                      curr_span = curr_span->next;
  
                      /* Check if we have a valid span in this dimension still */
                      if(NULL != curr_span) {
                          /* Reset the span in the current dimension */
                          ispan[curr_dim] = curr_span;
  
                          /* Reset absolute position */
                          abs_arr[curr_dim] = curr_span->low;
  
                          break;
                      } /* end if */
                      else {
                          /* If we finished the span list in this dimension, decrement the dimension worked on and loop again */
                          curr_dim--;
                      } /* end else */
                  } /* end else */
              } /* end while */
  
              /* Check if we have more spans in the tree */
              if(curr_dim >= 0) {
                  /* Walk back down the iterator positions, reseting them */
                  while((unsigned)curr_dim < fast_dim) {
                      HDassert(curr_span);
                      HDassert(curr_span->down);
                      HDassert(curr_span->down->head);
  
                      /* Increment current dimension */
                      curr_dim++;
  
                      /* Set the new span_info & span for this dimension */
                      iter->u.hyp.span[curr_dim] = curr_span->down->head;
  
                      /* Advance span down the tree */
                      curr_span = curr_span->down->head;
  
                      /* Reset the absolute offset for the dim */
                      abs_arr[curr_dim] = curr_span->low;
                  } /* end while */
  
                  /* Verify that the curr_span points to the fastest dim */
                  HDassert(curr_span == iter->u.hyp.span[fast_dim]);
  
                  /* Reset the buffer offset */
                  for(u = 0, loc_off = 0; u < ndims; u++)
                      loc_off += ((hsize_t)((hssize_t)abs_arr[u] + off_arr[u])) * slab[u];
              } /* end else */
              else
                  /* We had better be done with I/O or bad things are going to happen... */
                  HDassert(io_bytes_left == 0);
          } /* end if */
      } /* end if */
  
      /* Perform the I/O on the elements, based on the position of the iterator */
      while(io_bytes_left > 0 && curr_seq < maxseq) {
          /* Sanity check */
          HDassert(curr_span);
  
          /* Adjust location offset of destination to compensate for initial increment below */
          loc_off -= curr_span->pstride;
  
          /* Loop over all the spans in the fastest changing dimension */
          while(curr_span != NULL) {
              /* Move location offset of destination */
              loc_off += curr_span->pstride;
  
              /* Compute the number of elements to attempt in this span */
              H5_CHECKED_ASSIGN(span_size, size_t, curr_span->nelem, hsize_t);
  
              /* Check number of elements against upper bounds allowed */
              if(span_size >= io_bytes_left) {
                  /* Trim the number of bytes to output */
                  span_size = io_bytes_left;
                  io_bytes_left = 0;
  
  /* COMMON */
                  /* Store the I/O information for the span */
  
                  /* Check if this is appending onto previous sequence */
                  if(curr_seq > 0 && last_span_end == loc_off)
                      len[curr_seq - 1] += span_size;
                  else {
                      off[curr_seq] = loc_off;
                      len[curr_seq] = span_size;
  
                      /* Increment the number of sequences in arrays */
                      curr_seq++;
                  } /* end else */
  
                  /* Set the location of the last span's end */
                  last_span_end = loc_off + span_size;
  /* end COMMON */
  
                  /* Break out now, we are finished with I/O */
                  break;
              } /* end if */
              else {
                  /* Decrement I/O left to perform */
                  io_bytes_left -= span_size;
  
  /* COMMON */
                  /* Store the I/O information for the span */
  
                  /* Check if this is appending onto previous sequence */
                  if(curr_seq > 0 && last_span_end == loc_off)
                      len[curr_seq-1]+=span_size;
                  else {
                      off[curr_seq] = loc_off;
                      len[curr_seq] = span_size;
  
                      /* Increment the number of sequences in arrays */
                      curr_seq++;
                  } /* end else */
  
                  /* Set the location of the last span's end */
                  last_span_end = loc_off + span_size;
  /* end COMMON */
  
                  /* If the sequence & offset arrays are full, do what? */
                  if(curr_seq >= maxseq) {
                      /* Break out now, we are finished with sequences */
                      break;
                  } /* end else */
              } /* end else */
  
  	    /* Move to next span in fastest changing dimension */
  	    curr_span=curr_span->next;
          } /* end while */
  
          /* Check if we are done */
          if(io_bytes_left==0 || curr_seq>=maxseq) {
              HDassert(curr_span);
              abs_arr[fast_dim]=curr_span->low+(span_size/elem_size);
  
              /* Check if we are still within the span */
              if(abs_arr[fast_dim]<=curr_span->high) {
                  iter->u.hyp.span[fast_dim]=curr_span;
                  break;
              } /* end if */
              /* If we walked off that span, advance to the next span */
              else {
                  /* Advance span in this dimension */
                  curr_span=curr_span->next;
  
                  /* Check if we have a valid span in this dimension still */
                  if(curr_span!=NULL) {
                      /* Reset absolute position */
                      abs_arr[fast_dim]=curr_span->low;
                      iter->u.hyp.span[fast_dim]=curr_span;
                      break;
                  } /* end if */
              } /* end else */
          } /* end if */
  
          /* Adjust iterator pointers */
  
          /* Start at the next fastest dim */
          curr_dim = (int)(fast_dim - 1);
  
          /* Work back up through the dimensions */
          while(curr_dim >= 0) {
              /* Reset the current span */
  	    curr_span=iter->u.hyp.span[curr_dim];
  
              /* Increment absolute position */
              abs_arr[curr_dim]++;
  
              /* Check if we are still within the span */
              if(abs_arr[curr_dim]<=curr_span->high) {
                  break;
              } /* end if */
              /* If we walked off that span, advance to the next span */
              else {
                  /* Advance span in this dimension */
                  curr_span=curr_span->next;
  
                  /* Check if we have a valid span in this dimension still */
                  if(curr_span!=NULL) {
                      /* Reset the span in the current dimension */
                      ispan[curr_dim]=curr_span;
  
                      /* Reset absolute position */
                      abs_arr[curr_dim]=curr_span->low;
  
                      break;
                  } /* end if */
                  else {
                      /* If we finished the span list in this dimension, decrement the dimension worked on and loop again */
                      curr_dim--;
                  } /* end else */
              } /* end else */
          } /* end while */
  
          /* Check if we are finished with the spans in the tree */
          if(curr_dim < 0) {
              /* We had better be done with I/O or bad things are going to happen... */
              HDassert(io_bytes_left == 0);
              break;
          } /* end if */
          else {
              /* Walk back down the iterator positions, reseting them */
              while((unsigned)curr_dim < fast_dim) {
                  HDassert(curr_span);
                  HDassert(curr_span->down);
                  HDassert(curr_span->down->head);
  
                  /* Increment current dimension to the next dimension down */
                  curr_dim++;
  
                  /* Set the new span for the next dimension down */
                  iter->u.hyp.span[curr_dim] = curr_span->down->head;
  
                  /* Advance span down the tree */
                  curr_span = curr_span->down->head;
  
                  /* Reset the absolute offset for the dim */
                  abs_arr[curr_dim] = curr_span->low;
              } /* end while */
  
              /* Verify that the curr_span points to the fastest dim */
              HDassert(curr_span == iter->u.hyp.span[fast_dim]);
          } /* end else */
  
          /* Reset the buffer offset */
          for(u = 0, loc_off = 0; u < ndims; u++)
              loc_off += ((hsize_t)((hssize_t)abs_arr[u] + off_arr[u])) * slab[u];
      } /* end while */
  
      /* Decrement number of elements left in iterator */
      io_used = (io_left - (io_bytes_left / elem_size));
      iter->elmt_left -= io_used;
  
      /* Set the number of sequences generated */
      *nseq = curr_seq;
  
      /* Set the number of elements used */
      *nelem = io_used;
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  } /* end H5S_hyper_get_seq_list_gen() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_get_seq_list_opt
   PURPOSE
      Create a list of offsets & lengths for a selection
   USAGE
      herr_t H5S_select_hyper_get_file_list_opt(space,iter,maxseq,maxelem,nseq,nelem,off,len)
          H5S_t *space;           IN: Dataspace containing selection to use.
          H5S_sel_iter_t *iter;   IN/OUT: Selection iterator describing last
                                      position of interest in selection.
          size_t maxseq;          IN: Maximum number of sequences to generate
          size_t maxelem;         IN: Maximum number of elements to include in the
                                      generated sequences
          size_t *nseq;           OUT: Actual number of sequences generated
          size_t *nelem;          OUT: Actual number of elements in sequences generated
          hsize_t *off;           OUT: Array of offsets
          size_t *len;            OUT: Array of lengths
   RETURNS
      Non-negative on success/Negative on failure.
   DESCRIPTION
      Use the selection in the dataspace to generate a list of byte offsets and
      lengths for the region(s) selected.  Start/Restart from the position in the
      ITER parameter.  The number of sequences generated is limited by the MAXSEQ
      parameter and the number of sequences actually generated is stored in the
      NSEQ parameter.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_get_seq_list_opt(const H5S_t *space, H5S_sel_iter_t *iter,
      size_t maxseq, size_t maxelem, size_t *nseq, size_t *nelem,
      hsize_t *off, size_t *len)
  {
      hsize_t *mem_size;                  /* Size of the source buffer */
      hsize_t slab[H5O_LAYOUT_NDIMS];     /* Hyperslab size */
      const hssize_t *sel_off;            /* Selection offset in dataspace */
      hsize_t offset[H5O_LAYOUT_NDIMS];   /* Coordinate offset in dataspace */
      hsize_t tmp_count[H5O_LAYOUT_NDIMS];/* Temporary block count */
      hsize_t tmp_block[H5O_LAYOUT_NDIMS];/* Temporary block offset */
      hsize_t wrap[H5O_LAYOUT_NDIMS];     /* Bytes to wrap around at the end of a row */
      hsize_t skip[H5O_LAYOUT_NDIMS];     /* Bytes to skip between blocks */
      const H5S_hyper_dim_t *tdiminfo;    /* Temporary pointer to diminfo information */
      hsize_t fast_dim_start,    /* Local copies of fastest changing dimension info */
          fast_dim_stride,
          fast_dim_block,
          fast_dim_offset;
      size_t fast_dim_buf_off;    /* Local copy of amount to move fastest dimension buffer offset */
      size_t fast_dim_count;      /* Number of blocks left in fastest changing dimension */
      size_t tot_blk_count;       /* Total number of blocks left to output */
      size_t act_blk_count;       /* Actual number of blocks to output */
      size_t total_rows;          /* Total number of entire rows to output */
      size_t curr_rows;           /* Current number of entire rows to output */
      unsigned fast_dim;  /* Rank of the fastest changing dimension for the dataspace */
      unsigned ndims;     /* Number of dimensions of dataset */
      int temp_dim;       /* Temporary rank holder */
      hsize_t acc;	/* Accumulator */
      hsize_t loc;        /* Coordinate offset */
      size_t curr_seq = 0; /* Current sequence being operated on */
      size_t actual_elem; /* The actual number of elements to count */
      size_t actual_bytes;/* The actual number of bytes to copy */
      size_t io_left;     /* The number of elements left in I/O operation */
      size_t start_io_left; /* The initial number of elements left in I/O operation */
      size_t elem_size;   /* Size of each element iterating over */
      unsigned u;         /* Local index variable */
      int i;              /* Local index variable */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(space);
      HDassert(iter);
      HDassert(maxseq > 0);
      HDassert(maxelem > 0);
      HDassert(nseq);
      HDassert(nelem);
      HDassert(off);
      HDassert(len);
  
      /* Set the local copy of the diminfo pointer */
      tdiminfo = iter->u.hyp.diminfo;
  
      /* Check if this is a "flattened" regular hyperslab selection */
      if(iter->u.hyp.iter_rank != 0 && iter->u.hyp.iter_rank < space->extent.rank) {
          /* Set the aliases for a few important dimension ranks */
          ndims = iter->u.hyp.iter_rank;
          fast_dim = ndims - 1;
  
          /* Set the local copy of the selection offset */
          sel_off = iter->u.hyp.sel_off;
  
          /* Set up the pointer to the size of the memory space */
          mem_size = iter->u.hyp.size;
      } /* end if */
      else {
          /* Set the aliases for a few important dimension ranks */
          ndims = space->extent.rank;
          fast_dim = ndims - 1;
  
          /* Set the local copy of the selection offset */
          sel_off = space->select.offset;
  
          /* Set up the pointer to the size of the memory space */
          mem_size = space->extent.size;
      } /* end else */
  
      /* initialize row sizes for each dimension */
      elem_size = iter->elmt_size;
      for(i = (int)fast_dim, acc = elem_size; i >= 0; i--) {
          slab[i] = acc;
          acc *= mem_size[i];
      } /* end for */
  
      /* Calculate the number of elements to sequence through */
      H5_CHECK_OVERFLOW(iter->elmt_left, hsize_t, size_t);
      io_left = MIN((size_t)iter->elmt_left, maxelem);
  
      /* Sanity check that there aren't any "remainder" sequences in process */
      HDassert(!((iter->u.hyp.off[fast_dim] - tdiminfo[fast_dim].start) % tdiminfo[fast_dim].stride != 0 ||
              ((iter->u.hyp.off[fast_dim] != tdiminfo[fast_dim].start) && tdiminfo[fast_dim].count == 1)));
  
      /* We've cleared the "remainder" of the previous fastest dimension
       * sequence before calling this routine, so we must be at the beginning of
       * a sequence.  Use the fancy algorithm to compute the offsets and run
       * through as many as possible, until the buffer fills up.
       */
  
      /* Keep the number of elements we started with */
      start_io_left = io_left;
  
      /* Compute the arrays to perform I/O on */
  
      /* Copy the location of the point to get */
      /* (Add in the selection offset) */
      for(u = 0; u < ndims; u++)
          offset[u] = (hsize_t)((hssize_t)iter->u.hyp.off[u] + sel_off[u]);
  
      /* Compute the current "counts" for this location */
      for(u = 0; u < ndims; u++) {
          if(tdiminfo[u].count == 1) {
              tmp_count[u] = 0;
              tmp_block[u] = iter->u.hyp.off[u] - tdiminfo[u].start;
          } /* end if */
          else {
              tmp_count[u] = (iter->u.hyp.off[u] - tdiminfo[u].start) / tdiminfo[u].stride;
              tmp_block[u] = (iter->u.hyp.off[u] - tdiminfo[u].start) % tdiminfo[u].stride;
          } /* end else */
      } /* end for */
  
      /* Compute the initial buffer offset */
      for(u = 0, loc = 0; u < ndims; u++)
          loc += offset[u] * slab[u];
  
      /* Set the number of elements to write each time */
      H5_CHECKED_ASSIGN(actual_elem, size_t, tdiminfo[fast_dim].block, hsize_t);
  
      /* Set the number of actual bytes */
      actual_bytes = actual_elem * elem_size;
  
      /* Set local copies of information for the fastest changing dimension */
      fast_dim_start = tdiminfo[fast_dim].start;
      fast_dim_stride = tdiminfo[fast_dim].stride;
      fast_dim_block = tdiminfo[fast_dim].block;
      H5_CHECKED_ASSIGN(fast_dim_buf_off, size_t, slab[fast_dim] * fast_dim_stride, hsize_t);
      fast_dim_offset = (hsize_t)((hssize_t)fast_dim_start + sel_off[fast_dim]);
  
      /* Compute the number of blocks which would fit into the buffer */
      H5_CHECK_OVERFLOW(io_left / fast_dim_block, hsize_t, size_t);
      tot_blk_count = (size_t)(io_left / fast_dim_block);
  
      /* Don't go over the maximum number of sequences allowed */
      tot_blk_count = MIN(tot_blk_count, (maxseq - curr_seq));
  
      /* Compute the amount to wrap at the end of each row */
      for(u = 0; u < ndims; u++)
          wrap[u] = (mem_size[u] - (tdiminfo[u].stride * tdiminfo[u].count)) * slab[u];
  
      /* Compute the amount to skip between blocks */
      for(u = 0; u < ndims; u++)
          skip[u] = (tdiminfo[u].stride - tdiminfo[u].block) * slab[u];
  
      /* Check if there is a partial row left (with full blocks) */
      if(tmp_count[fast_dim] > 0) {
          /* Get number of blocks in fastest dimension */
          H5_CHECKED_ASSIGN(fast_dim_count, size_t, tdiminfo[fast_dim].count - tmp_count[fast_dim], hsize_t);
  
          /* Make certain this entire row will fit into buffer */
          fast_dim_count = MIN(fast_dim_count, tot_blk_count);
  
          /* Number of blocks to sequence over */
          act_blk_count = fast_dim_count;
  
          /* Loop over all the blocks in the fastest changing dimension */
          while(fast_dim_count > 0) {
              /* Store the sequence information */
              off[curr_seq] = loc;
              len[curr_seq] = actual_bytes;
  
              /* Increment sequence count */
              curr_seq++;
  
              /* Increment information to reflect block just processed */
              loc += fast_dim_buf_off;
  
              /* Decrement number of blocks */
              fast_dim_count--;
          } /* end while */
  
          /* Decrement number of elements left */
          io_left -= actual_elem * act_blk_count;
  
          /* Decrement number of blocks left */
          tot_blk_count -= act_blk_count;
  
          /* Increment information to reflect block just processed */
          tmp_count[fast_dim] += act_blk_count;
  
          /* Check if we finished the entire row of blocks */
          if(tmp_count[fast_dim] >= tdiminfo[fast_dim].count) {
              /* Increment offset in destination buffer */
              loc += wrap[fast_dim];
  
              /* Increment information to reflect block just processed */
              offset[fast_dim] = fast_dim_offset;    /* reset the offset in the fastest dimension */
              tmp_count[fast_dim] = 0;
  
              /* Increment the offset and count for the other dimensions */
              temp_dim = (int)fast_dim - 1;
              while(temp_dim >= 0) {
                  /* Move to the next row in the curent dimension */
                  offset[temp_dim]++;
                  tmp_block[temp_dim]++;
  
                  /* If this block is still in the range of blocks to output for the dimension, break out of loop */
                  if(tmp_block[temp_dim] < tdiminfo[temp_dim].block)
                      break;
                  else {
                      /* Move to the next block in the current dimension */
                      offset[temp_dim] += (tdiminfo[temp_dim].stride - tdiminfo[temp_dim].block);
                      loc += skip[temp_dim];
                      tmp_block[temp_dim] = 0;
                      tmp_count[temp_dim]++;
  
                      /* If this block is still in the range of blocks to output for the dimension, break out of loop */
                      if(tmp_count[temp_dim] < tdiminfo[temp_dim].count)
                          break;
                      else {
                          offset[temp_dim] = (hsize_t)((hssize_t)tdiminfo[temp_dim].start + sel_off[temp_dim]);
                          loc += wrap[temp_dim];
                          tmp_count[temp_dim] = 0; /* reset back to the beginning of the line */
                          tmp_block[temp_dim] = 0;
                      } /* end else */
                  } /* end else */
  
                  /* Decrement dimension count */
                  temp_dim--;
              } /* end while */
          } /* end if */
          else {
              /* Update the offset in the fastest dimension */
              offset[fast_dim] += (fast_dim_stride * act_blk_count);
          } /* end else */
      } /* end if */
  
      /* Compute the number of entire rows to read in */
      H5_CHECK_OVERFLOW(tot_blk_count / tdiminfo[fast_dim].count, hsize_t, size_t);
      curr_rows = total_rows = (size_t)(tot_blk_count / tdiminfo[fast_dim].count);
  
      /* Reset copy of number of blocks in fastest dimension */
      H5_CHECKED_ASSIGN(fast_dim_count, size_t, tdiminfo[fast_dim].count, hsize_t);
  
      /* Read in data until an entire sequence can't be written out any longer */
      while(curr_rows > 0) {
  
  #define DUFF_GUTS							      \
  /* Store the sequence information */				      \
  off[curr_seq] = loc;						      \
  len[curr_seq] = actual_bytes;					      \
                                                                            \
  /* Increment sequence count */					      \
  curr_seq++;								      \
                                                                            \
  /* Increment information to reflect block just processed */		      \
  loc += fast_dim_buf_off;
  
  #ifdef NO_DUFFS_DEVICE
          /* Loop over all the blocks in the fastest changing dimension */
          while(fast_dim_count > 0) {
              DUFF_GUTS
  
              /* Decrement number of blocks */
              fast_dim_count--;
          } /* end while */
  #else /* NO_DUFFS_DEVICE */
          {
              size_t duffs_index; /* Counting index for Duff's device */
  
              duffs_index = (fast_dim_count + 7) / 8;
              switch (fast_dim_count % 8) {
                  default:
                      HDassert(0 && "This Should never be executed!");
                      break;
                  case 0:
                      do
                        {
                          DUFF_GUTS
                  case 7:
                          DUFF_GUTS
                  case 6:
                          DUFF_GUTS
                  case 5:
                          DUFF_GUTS
                  case 4:
                          DUFF_GUTS
                  case 3:
                          DUFF_GUTS
                  case 2:
                          DUFF_GUTS
                  case 1:
                          DUFF_GUTS
                    } while (--duffs_index > 0);
              } /* end switch */
          }
  #endif /* NO_DUFFS_DEVICE */
  #undef DUFF_GUTS
  
          /* Increment offset in destination buffer */
          loc += wrap[fast_dim];
  
          /* Increment the offset and count for the other dimensions */
          temp_dim = (int)fast_dim - 1;
          while(temp_dim >= 0) {
              /* Move to the next row in the curent dimension */
              offset[temp_dim]++;
              tmp_block[temp_dim]++;
  
              /* If this block is still in the range of blocks to output for the dimension, break out of loop */
              if(tmp_block[temp_dim] < tdiminfo[temp_dim].block)
                  break;
              else {
                  /* Move to the next block in the current dimension */
                  offset[temp_dim] += (tdiminfo[temp_dim].stride - tdiminfo[temp_dim].block);
                  loc += skip[temp_dim];
                  tmp_block[temp_dim] = 0;
                  tmp_count[temp_dim]++;
  
                  /* If this block is still in the range of blocks to output for the dimension, break out of loop */
                  if(tmp_count[temp_dim] < tdiminfo[temp_dim].count)
                      break;
                  else {
                      offset[temp_dim] = (hsize_t)((hssize_t)tdiminfo[temp_dim].start + sel_off[temp_dim]);
                      loc += wrap[temp_dim];
                      tmp_count[temp_dim] = 0; /* reset back to the beginning of the line */
                      tmp_block[temp_dim] = 0;
                  } /* end else */
              } /* end else */
  
              /* Decrement dimension count */
              temp_dim--;
          } /* end while */
  
          /* Decrement the number of rows left */
          curr_rows--;
      } /* end while */
  
      /* Adjust the number of blocks & elements left to transfer */
  
      /* Decrement number of elements left */
      H5_CHECK_OVERFLOW(actual_elem * (total_rows * tdiminfo[fast_dim].count), hsize_t, size_t);
      io_left -= (size_t)(actual_elem * (total_rows * tdiminfo[fast_dim].count));
  
      /* Decrement number of blocks left */
      H5_CHECK_OVERFLOW((total_rows * tdiminfo[fast_dim].count), hsize_t, size_t);
      tot_blk_count -= (size_t)(total_rows * tdiminfo[fast_dim].count);
  
      /* Read in partial row of blocks */
      if(io_left > 0 && curr_seq < maxseq) {
          /* Get remaining number of blocks left to output */
          fast_dim_count = tot_blk_count;
  
          /* Loop over all the blocks in the fastest changing dimension */
          while(fast_dim_count > 0) {
              /* Store the sequence information */
              off[curr_seq] = loc;
              len[curr_seq] = actual_bytes;
  
              /* Increment sequence count */
              curr_seq++;
  
              /* Increment information to reflect block just processed */
              loc += fast_dim_buf_off;
  
              /* Decrement number of blocks */
              fast_dim_count--;
          } /* end while */
  
          /* Decrement number of elements left */
          io_left -= actual_elem * tot_blk_count;
  
          /* Increment information to reflect block just processed */
          offset[fast_dim] += (fast_dim_stride * tot_blk_count);    /* move the offset in the fastest dimension */
  
          /* Handle any leftover, partial blocks in this row */
          if(io_left > 0 && curr_seq < maxseq) {
              actual_elem = io_left;
              actual_bytes = actual_elem * elem_size;
  
              /* Store the sequence information */
              off[curr_seq] = loc;
              len[curr_seq] = actual_bytes;
  
              /* Increment sequence count */
              curr_seq++;
  
              /* Decrement the number of elements left */
              io_left -= actual_elem;
  
              /* Increment buffer correctly */
              offset[fast_dim] += actual_elem;
          } /* end if */
  
          /* don't bother checking slower dimensions */
          HDassert(io_left == 0 || curr_seq == maxseq);
      } /* end if */
  
      /* Update the iterator */
  
      /* Update the iterator with the location we stopped */
      /* (Subtract out the selection offset) */
      for(u = 0; u < ndims; u++)
          iter->u.hyp.off[u] = (hsize_t)((hssize_t)offset[u] - sel_off[u]);
  
      /* Decrement the number of elements left in selection */
      iter->elmt_left -= (start_io_left - io_left);
  
      /* Increment the number of sequences generated */
      *nseq += curr_seq;
  
      /* Increment the number of elements used */
      *nelem += start_io_left - io_left;
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  } /* end H5S_hyper_get_seq_list_opt() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_get_seq_list_single
   PURPOSE
      Create a list of offsets & lengths for a selection
   USAGE
      herr_t H5S_hyper_get_seq_list_single(space, flags, iter, maxseq, maxelem, nseq, nelem, off, len)
          H5S_t *space;           IN: Dataspace containing selection to use.
          unsigned flags;         IN: Flags for extra information about operation
          H5S_sel_iter_t *iter;   IN/OUT: Selection iterator describing last
                                      position of interest in selection.
          size_t maxseq;          IN: Maximum number of sequences to generate
          size_t maxelem;         IN: Maximum number of elements to include in the
                                      generated sequences
          size_t *nseq;           OUT: Actual number of sequences generated
          size_t *nelem;          OUT: Actual number of elements in sequences generated
          hsize_t *off;           OUT: Array of offsets
          size_t *len;            OUT: Array of lengths
   RETURNS
      Non-negative on success/Negative on failure.
   DESCRIPTION
      Use the selection in the dataspace to generate a list of byte offsets and
      lengths for the region(s) selected.  Start/Restart from the position in the
      ITER parameter.  The number of sequences generated is limited by the MAXSEQ
      parameter and the number of sequences actually generated is stored in the
      NSEQ parameter.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_get_seq_list_single(const H5S_t *space, H5S_sel_iter_t *iter,
      size_t maxseq, size_t maxelem, size_t *nseq, size_t *nelem,
      hsize_t *off, size_t *len)
  {
      const H5S_hyper_dim_t *tdiminfo;    /* Temporary pointer to diminfo information */
      const hssize_t *sel_off;    /* Selection offset in dataspace */
      hsize_t *mem_size;      /* Size of the source buffer */
      hsize_t base_offset[H5O_LAYOUT_NDIMS];   /* Base coordinate offset in dataspace */
      hsize_t offset[H5O_LAYOUT_NDIMS];   /* Coordinate offset in dataspace */
      hsize_t slab[H5O_LAYOUT_NDIMS];     /* Hyperslab size */
      hsize_t fast_dim_block;     /* Local copies of fastest changing dimension info */
      hsize_t acc;	        /* Accumulator */
      hsize_t loc;                /* Coordinate offset */
      size_t tot_blk_count;       /* Total number of blocks left to output */
      size_t elem_size;           /* Size of each element iterating over */
      size_t io_left;             /* The number of elements left in I/O operation */
      size_t actual_elem;         /* The actual number of elements to count */
      unsigned ndims;             /* Number of dimensions of dataset */
      unsigned fast_dim;          /* Rank of the fastest changing dimension for the dataspace */
      unsigned skip_dim;          /* Rank of the dimension to skip along */
      unsigned u;                 /* Local index variable */
      int i;                      /* Local index variable */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(space);
      HDassert(iter);
      HDassert(maxseq > 0);
      HDassert(maxelem > 0);
      HDassert(nseq);
      HDassert(nelem);
      HDassert(off);
      HDassert(len);
  
      /* Set a local copy of the diminfo pointer */
      tdiminfo = iter->u.hyp.diminfo;
  
      /* Check if this is a "flattened" regular hyperslab selection */
      if(iter->u.hyp.iter_rank != 0 && iter->u.hyp.iter_rank < space->extent.rank) {
          /* Set the aliases for a few important dimension ranks */
          ndims = iter->u.hyp.iter_rank;
  
          /* Set the local copy of the selection offset */
          sel_off = iter->u.hyp.sel_off;
  
          /* Set up the pointer to the size of the memory space */
          mem_size = iter->u.hyp.size;
      } /* end if */
      else {
          /* Set the aliases for a few important dimension ranks */
          ndims = space->extent.rank;
  
          /* Set the local copy of the selection offset */
          sel_off = space->select.offset;
  
          /* Set up the pointer to the size of the memory space */
          mem_size = space->extent.size;
      } /* end else */
      fast_dim = ndims - 1;
  
      /* initialize row sizes for each dimension */
      elem_size = iter->elmt_size;
      for(i = (int)fast_dim, acc = elem_size; i >= 0; i--) {
          slab[i] = acc;
          acc *= mem_size[i];
      } /* end for */
  
      /* Copy the base location of the block */
      /* (Add in the selection offset) */
      for(u = 0; u < ndims; u++)
          base_offset[u] = (hsize_t)((hssize_t)tdiminfo[u].start + sel_off[u]);
  
      /* Copy the location of the point to get */
      /* (Add in the selection offset) */
      for(u = 0; u < ndims; u++)
          offset[u] = (hsize_t)((hssize_t)iter->u.hyp.off[u] + sel_off[u]);
  
      /* Compute the initial buffer offset */
      for(u = 0, loc = 0; u < ndims; u++)
          loc += offset[u] * slab[u];
  
      /* Set local copies of information for the fastest changing dimension */
      fast_dim_block = tdiminfo[fast_dim].block;
  
      /* Calculate the number of elements to sequence through */
      H5_CHECK_OVERFLOW(iter->elmt_left, hsize_t, size_t);
      io_left = MIN((size_t)iter->elmt_left, maxelem);
  
      /* Compute the number of blocks which would fit into the buffer */
      H5_CHECK_OVERFLOW(io_left / fast_dim_block, hsize_t, size_t);
      tot_blk_count = (size_t)(io_left / fast_dim_block);
  
      /* Don't go over the maximum number of sequences allowed */
      tot_blk_count = MIN(tot_blk_count, maxseq);
  
      /* Set the number of elements to write each time */
      H5_CHECKED_ASSIGN(actual_elem, size_t, fast_dim_block, hsize_t);
  
      /* Check for blocks to operate on */
      if(tot_blk_count > 0) {
          size_t actual_bytes;        /* The actual number of bytes to copy */
  
          /* Set the number of actual bytes */
          actual_bytes = actual_elem * elem_size;
  
          /* Check for 1-dim selection */
          if(0 == fast_dim) {
              /* Sanity checks */
              HDassert(1 == tot_blk_count);
              HDassert(io_left == actual_elem);
  
              /* Store the sequence information */
              *off++ = loc;
              *len++ = actual_bytes;
          } /* end if */
          else {
              hsize_t skip_slab;          /* Temporary copy of slab[fast_dim - 1] */
              size_t blk_count;           /* Total number of blocks left to output */
  
              /* Find first dimension w/block >1 */
              skip_dim = fast_dim;
              for(i = (int)(fast_dim - 1); i >= 0; i--)
                  if(tdiminfo[i].block > 1) {
                      skip_dim = (unsigned)i;
                      break;
                  } /* end if */
              skip_slab = slab[skip_dim];
  
              /* Check for being able to use fast algorithm for 1-D */
              if(0 == skip_dim) {
                  /* Create sequences until an entire row can't be used */
                  blk_count = tot_blk_count;
                  while(blk_count > 0) {
                      /* Store the sequence information */
                      *off++ = loc;
                      *len++ = actual_bytes;
  
                      /* Increment offset in destination buffer */
                      loc += skip_slab;
  
                      /* Decrement block count */
                      blk_count--;
                  } /* end while */
  
                  /* Move to the next location */
                  offset[skip_dim] += tot_blk_count;
              } /* end if */
              else {
                  hsize_t tmp_block[H5O_LAYOUT_NDIMS];/* Temporary block offset */
                  hsize_t skip[H5O_LAYOUT_NDIMS];     /* Bytes to skip between blocks */
                  int temp_dim;               /* Temporary rank holder */
  
                  /* Set the starting block location */
                  for(u = 0; u < ndims; u++)
                      tmp_block[u] = iter->u.hyp.off[u] - tdiminfo[u].start;
  
                  /* Compute the amount to skip between sequences */
                  for(u = 0; u < ndims; u++)
                      skip[u] = (mem_size[u] - tdiminfo[u].block) * slab[u];
  
                  /* Create sequences until an entire row can't be used */
                  blk_count = tot_blk_count;
                  while(blk_count > 0) {
                      /* Store the sequence information */
                      *off++ = loc;
                      *len++ = actual_bytes;
  
                      /* Set temporary dimension for advancing offsets */
                      temp_dim = (int)skip_dim;
  
                      /* Increment offset in destination buffer */
                      loc += skip_slab;
  
                      /* Increment the offset and count for the other dimensions */
                      while(temp_dim >= 0) {
                          /* Move to the next row in the curent dimension */
                          offset[temp_dim]++;
                          tmp_block[temp_dim]++;
  
                          /* If this block is still in the range of blocks to output for the dimension, break out of loop */
                          if(tmp_block[temp_dim] < tdiminfo[temp_dim].block)
                              break;
                          else {
                              offset[temp_dim] = base_offset[temp_dim];
                              loc += skip[temp_dim];
                              tmp_block[temp_dim] = 0;
                          } /* end else */
  
                          /* Decrement dimension count */
                          temp_dim--;
                      } /* end while */
  
                      /* Decrement block count */
                      blk_count--;
                  } /* end while */
              } /* end else */
          } /* end else */
  
          /* Update the iterator, if there were any blocks used */
  
          /* Decrement the number of elements left in selection */
          iter->elmt_left -= tot_blk_count * actual_elem;
  
          /* Check if there are elements left in iterator */
          if(iter->elmt_left > 0) {
              /* Update the iterator with the location we stopped */
              /* (Subtract out the selection offset) */
              for(u = 0; u < ndims; u++)
                  iter->u.hyp.off[u] = (hsize_t)((hssize_t)offset[u] - sel_off[u]);
          } /* end if */
  
          /* Increment the number of sequences generated */
          *nseq += tot_blk_count;
  
          /* Increment the number of elements used */
          *nelem += tot_blk_count * actual_elem;
      } /* end if */
  
      /* Check for partial block, with room for another sequence */
      if(io_left > (tot_blk_count * actual_elem) && tot_blk_count < maxseq) {
          size_t elmt_remainder;  /* Elements remaining */
  
          /* Compute elements left */
          elmt_remainder = io_left - (tot_blk_count * actual_elem);
          HDassert(elmt_remainder < fast_dim_block);
          HDassert(elmt_remainder > 0);
  
          /* Store the sequence information */
          *off++ = loc;
          *len++ = elmt_remainder * elem_size;
  
          /* Update the iterator with the location we stopped */
          iter->u.hyp.off[fast_dim] += (hsize_t)elmt_remainder;
  
          /* Decrement the number of elements left in selection */
          iter->elmt_left -= elmt_remainder;
  
          /* Increment the number of sequences generated */
          (*nseq)++;
  
          /* Increment the number of elements used */
          *nelem += elmt_remainder;
      } /* end if */
  
      /* Sanity check */
      HDassert(*nseq > 0);
      HDassert(*nelem > 0);
  
      FUNC_LEAVE_NOAPI(SUCCEED)
  } /* end H5S_hyper_get_seq_list_single() */
  
  
  /*--------------------------------------------------------------------------
   NAME
      H5S_hyper_get_seq_list
   PURPOSE
      Create a list of offsets & lengths for a selection
   USAGE
      herr_t H5S_hyper_get_seq_list(space,flags,iter,maxseq,maxelem,nseq,nelem,off,len)
          H5S_t *space;           IN: Dataspace containing selection to use.
          unsigned flags;         IN: Flags for extra information about operation
          H5S_sel_iter_t *iter;   IN/OUT: Selection iterator describing last
                                      position of interest in selection.
          size_t maxseq;          IN: Maximum number of sequences to generate
          size_t maxelem;         IN: Maximum number of elements to include in the
                                      generated sequences
          size_t *nseq;           OUT: Actual number of sequences generated
          size_t *nelem;          OUT: Actual number of elements in sequences generated
          hsize_t *off;           OUT: Array of offsets
          size_t *len;            OUT: Array of lengths
   RETURNS
      Non-negative on success/Negative on failure.
   DESCRIPTION
      Use the selection in the dataspace to generate a list of byte offsets and
      lengths for the region(s) selected.  Start/Restart from the position in the
      ITER parameter.  The number of sequences generated is limited by the MAXSEQ
      parameter and the number of sequences actually generated is stored in the
      NSEQ parameter.
   GLOBAL VARIABLES
   COMMENTS, BUGS, ASSUMPTIONS
   EXAMPLES
   REVISION LOG
  --------------------------------------------------------------------------*/
  static herr_t
  H5S_hyper_get_seq_list(const H5S_t *space, unsigned H5_ATTR_UNUSED flags, H5S_sel_iter_t *iter,
      size_t maxseq, size_t maxelem, size_t *nseq, size_t *nelem,
      hsize_t *off, size_t *len)
  {
      herr_t ret_value;      /* return value */
  
      FUNC_ENTER_NOAPI_NOINIT_NOERR
  
      /* Check args */
      HDassert(space);
      HDassert(iter);
      HDassert(iter->elmt_left > 0);
      HDassert(maxseq > 0);
      HDassert(maxelem > 0);
      HDassert(nseq);
      HDassert(nelem);
      HDassert(off);
      HDassert(len);
  
      /* Check for the special case of just one H5Sselect_hyperslab call made */
      if(space->select.sel_info.hslab->diminfo_valid) {
          const H5S_hyper_dim_t *tdiminfo;    /* Temporary pointer to diminfo information */
          const hssize_t *sel_off;    /* Selection offset in dataspace */
          hsize_t *mem_size;      /* Size of the source buffer */
          unsigned ndims;         /* Number of dimensions of dataset */
          unsigned fast_dim;      /* Rank of the fastest changing dimension for the dataspace */
          hbool_t single_block;   /* Whether the selection is a single block */
          unsigned u;             /* Local index variable */
  
          /* Set a local copy of the diminfo pointer */
          tdiminfo = iter->u.hyp.diminfo;
  
          /* Check if this is a "flattened" regular hyperslab selection */
          if(iter->u.hyp.iter_rank != 0 && iter->u.hyp.iter_rank < space->extent.rank) {
              /* Set the aliases for a few important dimension ranks */
              ndims = iter->u.hyp.iter_rank;
  
              /* Set the local copy of the selection offset */
              sel_off = iter->u.hyp.sel_off;
  
              /* Set up the pointer to the size of the memory space */
              mem_size = iter->u.hyp.size;
          } /* end if */
          else {
              /* Set the aliases for a few important dimension ranks */
              ndims = space->extent.rank;
  
              /* Set the local copy of the selection offset */
              sel_off = space->select.offset;
  
              /* Set up the pointer to the size of the memory space */
              mem_size = space->extent.size;
          } /* end else */
          fast_dim = ndims - 1;
  
          /* Check if we stopped in the middle of a sequence of elements */
          if((iter->u.hyp.off[fast_dim] - tdiminfo[fast_dim].start) % tdiminfo[fast_dim].stride != 0 ||
                  ((iter->u.hyp.off[fast_dim] != tdiminfo[fast_dim].start) && tdiminfo[fast_dim].count == 1)) {
              hsize_t slab[H5O_LAYOUT_NDIMS];     /* Hyperslab size */
              hsize_t loc;                /* Coordinate offset */
              hsize_t acc;	        /* Accumulator */
              size_t leftover;            /* The number of elements left over from the last sequence */
              size_t actual_elem;         /* The actual number of elements to count */
              size_t elem_size;           /* Size of each element iterating over */
              int i;                      /* Local index variable */
  
  
              /* Calculate the number of elements left in the sequence */
              if(tdiminfo[fast_dim].count == 1) {
                  H5_CHECKED_ASSIGN(leftover, size_t, tdiminfo[fast_dim].block - (iter->u.hyp.off[fast_dim] - tdiminfo[fast_dim].start), hsize_t);
              } /* end if */
              else {
                  H5_CHECKED_ASSIGN(leftover, size_t, tdiminfo[fast_dim].block - ((iter->u.hyp.off[fast_dim] - tdiminfo[fast_dim].start) % tdiminfo[fast_dim].stride), hsize_t);
              } /* end else */
  
              /* Make certain that we don't write too many */
              actual_elem = MIN3(leftover, (size_t)iter->elmt_left, maxelem);
  
              /* initialize row sizes for each dimension */
              elem_size = iter->elmt_size;
              for(i = (int)fast_dim, acc = elem_size; i >= 0; i--) {
                  slab[i] = acc;
                  acc *= mem_size[i];
              } /* end for */
  
              /* Compute the initial buffer offset */
              for(u = 0, loc = 0; u < ndims; u++)
                  loc += ((hsize_t)((hssize_t)iter->u.hyp.off[u] + sel_off[u])) * slab[u];
  
              /* Add a new sequence */
              off[0] = loc;
              H5_CHECKED_ASSIGN(len[0], size_t, actual_elem * elem_size, hsize_t);
  
              /* Increment sequence array locations */
              off++;
              len++;
  
              /* Advance the hyperslab iterator */
              H5S_hyper_iter_next(iter, actual_elem);
  
              /* Decrement the number of elements left in selection */
              iter->elmt_left -= actual_elem;
  
              /* Decrement element/sequence limits */
              maxelem -= actual_elem;
              maxseq--;
  
              /* Set the number of sequences generated and elements used */
              *nseq = 1;
              *nelem = actual_elem;
  
              /* Check for using up all the sequences/elements */
              if(0 == iter->elmt_left || 0 == maxelem || 0 == maxseq)
                  return(SUCCEED);
          } /* end if */
          else {
              /* Reset the number of sequences generated and elements used */
              *nseq = 0;
              *nelem = 0;
          } /* end else */
  
          /* Check for a single block selected */
          single_block = TRUE;
          for(u = 0; u < ndims; u++)
              if(1 != tdiminfo[u].count) {
                  single_block = FALSE;
                  break;
              } /* end if */
  
          /* Check for single block selection */
          if(single_block)
              /* Use single-block optimized call to generate sequence list */
              ret_value = H5S_hyper_get_seq_list_single(space, iter, maxseq, maxelem, nseq, nelem, off, len);
          else
              /* Use optimized call to generate sequence list */
              ret_value = H5S_hyper_get_seq_list_opt(space, iter, maxseq, maxelem, nseq, nelem, off, len);
      } /* end if */
      else
          /* Call the general sequence generator routine */
          ret_value = H5S_hyper_get_seq_list_gen(space, iter, maxseq, maxelem, nseq, nelem, off, len);
  
      FUNC_LEAVE_NOAPI(ret_value)
  } /* end H5S_hyper_get_seq_list() */
  
  