text: /* -*- Mode: C; c-basic-offset:4 ; indent-tabs-mode:nil ; -*- 
   * vim: ts=8 sts=4 sw=4 noexpandtab 
   * 
   *   Copyright (C) 2008 University of Chicago. 
   *   See COPYRIGHT notice in top-level directory.
   */
  
  #include "adio.h"
  #include "adio_extern.h"
  #include "ad_zoidfs.h"
  
  #include "ad_zoidfs_common.h"
  
  /* Copied from ADIOI_PVFS2_OldReadStrided.  It would be good to have fewer
   * copies of this code... */
  void ADIOI_ZOIDFS_ReadStrided(ADIO_File fd, void *buf, int count,
  			     MPI_Datatype datatype, int file_ptr_type,
  			     ADIO_Offset offset, ADIO_Status *status, int
  			     *error_code)
  {
      /* offset is in units of etype relative to the filetype. */
      ADIOI_Flatlist_node *flat_buf, *flat_file;
      int i, j, k,  brd_size, frd_size=0, st_index=0;
      int sum, n_etypes_in_filetype, size_in_filetype;
      MPI_Count bufsize;
      int n_filetypes, etype_in_filetype;
      ADIO_Offset abs_off_in_filetype=0;
      MPI_Count filetype_size, etype_size, buftype_size;
      MPI_Aint filetype_extent, buftype_extent, filetype_lb, buftype_lb; 
      int buf_count, buftype_is_contig, filetype_is_contig;
      ADIO_Offset off, disp, start_off, initial_off;
      int flag, st_frd_size, st_n_filetypes;
  
      size_t mem_list_count, file_list_count;
      void ** mem_offsets;
      uint64_t *file_offsets;
      size_t *mem_lengths;
      uint64_t *file_lengths;
      int total_blks_to_read;
  
      int max_mem_list, max_file_list;
  
      int b_blks_read;
      int f_data_read;
      int size_read=0, n_read_lists, extra_blks;
  
      int end_brd_size, end_frd_size;
      int start_k, start_j, new_file_read, new_buffer_read;
      int start_mem_offset;
      ADIOI_ZOIDFS_object * zoidfs_obj_ptr;
      int err_flag=0;
      MPI_Offset total_bytes_read = 0;
      static char myname[] = "ADIOI_ZOIDFS_ReadStrided";
  
      /* note: I don't know what zoidfs will do if you pass it a super-long list,
       * so let's keep with the PVFS limit for now */
  #define MAX_ARRAY_SIZE 64
  
      *error_code = MPI_SUCCESS;  /* changed below if error */
  
      ADIOI_Datatype_iscontig(datatype, &buftype_is_contig);
      ADIOI_Datatype_iscontig(fd->filetype, &filetype_is_contig);
  
      /* the HDF5 tests showed a bug in this list processing code (see many many
       * lines down below).  We added a workaround, but common HDF5 file types
       * are actually contiguous and do not need the expensive workarond */
      if (!filetype_is_contig) {
  	flat_file = ADIOI_Flatlist;
  	while (flat_file->type != fd->filetype) flat_file = flat_file->next;
  	if (flat_file->count == 1 && !buftype_is_contig)
  	    filetype_is_contig = 1;
      }
  
      MPI_Type_size_x(fd->filetype, &filetype_size);
      if ( ! filetype_size ) {
  #ifdef HAVE_STATUS_SET_BYTES
  	MPIR_Status_set_bytes(status, datatype, 0);
  #endif
  	*error_code = MPI_SUCCESS; 
  	return;
      }
  
      MPI_Type_get_extent(fd->filetype, &filetype_lb, &filetype_extent);
      MPI_Type_size_x(datatype, &buftype_size);
      MPI_Type_get_extent(datatype, &buftype_lb, &buftype_extent);
      etype_size = fd->etype_size;
  
      bufsize = buftype_size * count;
      
      zoidfs_obj_ptr = (ADIOI_ZOIDFS_object *)fd->fs_ptr;
  
      if (!buftype_is_contig && filetype_is_contig) {
  
  /* noncontiguous in memory, contiguous in file. */
          uint64_t file_offsets;
  	uint64_t file_lengths;
  
  	flat_buf = ADIOI_Flatten_and_find(datatype);
  
  	off = (file_ptr_type == ADIO_INDIVIDUAL) ? fd->fp_ind : 
  	    fd->disp + etype_size * offset;
  
  	file_list_count = 1;
  	file_offsets = off;
  	file_lengths = 0;
  	total_blks_to_read = count*flat_buf->count;
  	b_blks_read = 0;
  
  	/* allocate arrays according to max usage */
  	if (total_blks_to_read > MAX_ARRAY_SIZE)
  	    mem_list_count = MAX_ARRAY_SIZE;
  	else mem_list_count = total_blks_to_read;
  	mem_offsets = (void*)ADIOI_Malloc(mem_list_count*sizeof(void*));
  	mem_lengths = (size_t*)ADIOI_Malloc(mem_list_count*sizeof(size_t));
  
  	/* TODO: CHECK RESULTS OF MEMORY ALLOCATION */
  
  	j = 0;
  	/* step through each block in memory, filling memory arrays */
  	while (b_blks_read < total_blks_to_read) {
  	    for (i=0; i<flat_buf->count; i++) {
  		mem_offsets[b_blks_read % MAX_ARRAY_SIZE] = 
  		    buf + j*buftype_extent + flat_buf->indices[i];
  		mem_lengths[b_blks_read % MAX_ARRAY_SIZE] = 
  		    flat_buf->blocklens[i];
  		file_lengths += flat_buf->blocklens[i];
  		b_blks_read++;
  		if (!(b_blks_read % MAX_ARRAY_SIZE) ||
  		    (b_blks_read == total_blks_to_read)) {
  
  		    /* in the case of the last read list call,
  		       adjust mem_list_count */
  		    if (b_blks_read == total_blks_to_read) {
  		        mem_list_count = total_blks_to_read % MAX_ARRAY_SIZE;
  			/* in case last read list call fills max arrays */
  			if (!mem_list_count) mem_list_count = MAX_ARRAY_SIZE;
  		    }
  #ifdef ADIOI_MPE_LOGGING
                      MPE_Log_event( ADIOI_MPE_read_a, 0, NULL );
  #endif
  		    NO_STALE(err_flag, fd, zoidfs_obj_ptr,
  				    zoidfs_read(zoidfs_obj_ptr,
  					    mem_list_count,
  					    mem_offsets, mem_lengths,
  					    1, &file_offsets, &file_lengths, ZOIDFS_NO_OP_HINT));
  #ifdef ADIOI_MPE_LOGGING
                      MPE_Log_event( ADIOI_MPE_read_b, 0, NULL );
  #endif
  		    /* --BEGIN ERROR HANDLING-- */
  		    if (err_flag != ZFS_OK) {
  			*error_code = MPIO_Err_create_code(MPI_SUCCESS,
  							   MPIR_ERR_RECOVERABLE,
  							   myname, __LINE__,
  							   ADIOI_ZOIDFS_error_convert(err_flag),
  							   "Error in zoidfs_read", 0);
  			goto error_state;
  		    }
  		    total_bytes_read += file_lengths;
  		    /* --END ERROR HANDLING-- */
  		  
  		    /* in the case of error or the last read list call, 
  		     * leave here */
  		    if (err_flag || b_blks_read == total_blks_to_read) break;
  
  		    file_offsets += file_lengths;
  		    file_lengths = 0;
  		} 
  	    } /* for (i=0; i<flat_buf->count; i++) */
  	    j++;
  	} /* while (b_blks_read < total_blks_to_read) */
  	ADIOI_Free(mem_offsets);
  	ADIOI_Free(mem_lengths);
  
          if (file_ptr_type == ADIO_INDIVIDUAL) 
  	    fd->fp_ind += total_bytes_read;
  
  	fd->fp_sys_posn = -1;  /* set it to null. */
  
  #ifdef HAVE_STATUS_SET_BYTES
  	MPIR_Status_set_bytes(status, datatype, bufsize);
  	/* This isa temporary way of filling in status.  The right way is to
  	   keep tracke of how much data was actually read adn placed in buf
  	   by ADIOI_BUFFERED_READ. */
  #endif
  	ADIOI_Delete_flattened(datatype);
  
  	return;
      } /* if (!buftype_is_contig && filetype_is_contig) */
  
      /* know file is noncontiguous from above */
      /* noncontiguous in file */
  
      /* filetype already flattened in ADIO_Open */
      flat_file = ADIOI_Flatlist;
      while (flat_file->type != fd->filetype) flat_file = flat_file->next;
  
      disp = fd->disp;
      initial_off = offset;
  
  
      /* for each case - ADIO_Individual pointer or explicit, find the file
         offset in bytes (offset), n_filetypes (how many filetypes into
         file to start), frd_size (remaining amount of data in present
         file block), and st_index (start point in terms of blocks in
         starting filetype) */
      if (file_ptr_type == ADIO_INDIVIDUAL) {
          offset = fd->fp_ind; /* in bytes */
  	n_filetypes = -1;
  	flag = 0;
  	while (!flag) {
  	    n_filetypes++;
  	    for (i=0; i<flat_file->count; i++) {
  	        if (disp + flat_file->indices[i] + 
  		    ((ADIO_Offset) n_filetypes)*filetype_extent +
  		    flat_file->blocklens[i]  >= offset) {
  		    st_index = i;
  		    frd_size = disp + flat_file->indices[i] + 
  				    ((ADIO_Offset) n_filetypes)*filetype_extent
  				      + flat_file->blocklens[i] - offset;
  		    flag = 1;
  		    break;
  		}
  	    }
  	} /* while (!flag) */
      } /* if (file_ptr_type == ADIO_INDIVIDUAL) */
      else {
          n_etypes_in_filetype = filetype_size/etype_size;
  	n_filetypes = (int) (offset / n_etypes_in_filetype);
  	etype_in_filetype = (int) (offset % n_etypes_in_filetype);
  	size_in_filetype = etype_in_filetype * etype_size;
  	
  	sum = 0;
  	for (i=0; i<flat_file->count; i++) {
  	    sum += flat_file->blocklens[i];
  	    if (sum > size_in_filetype) {
  	        st_index = i;
  		frd_size = sum - size_in_filetype;
  		abs_off_in_filetype = flat_file->indices[i] +
  		    size_in_filetype - (sum - flat_file->blocklens[i]);
  		break;
  	    }
  	}
  	
  	/* abs. offset in bytes in the file */
  	offset = disp + ((ADIO_Offset) n_filetypes)*filetype_extent + 
  	    abs_off_in_filetype;
      } /* else [file_ptr_type != ADIO_INDIVIDUAL] */
  
      start_off = offset;
      st_frd_size = frd_size;
      st_n_filetypes = n_filetypes;
      
      if (buftype_is_contig && !filetype_is_contig) {
  
  /* contiguous in memory, noncontiguous in file. should be the most
     common case. */
  
  	/* only one memory off-len pair, so no array here */
          size_t mem_lengths;
  	size_t mem_offsets;
  	
  	i = 0;
  	j = st_index;
  	n_filetypes = st_n_filetypes;
  	
  	mem_list_count = 1;
  	
  	/* determine how many blocks in file to read */
  	f_data_read = ADIOI_MIN(st_frd_size, bufsize);
  	total_blks_to_read = 1;
  	if (j < (flat_file->count-1)) j++;
  	else {
  	    j = 0;
  	    n_filetypes++;
  	}
  	while (f_data_read < bufsize) {
  	    f_data_read += flat_file->blocklens[j];
  	    total_blks_to_read++;
  	    if (j<(flat_file->count-1)) j++;
  	    else j = 0;	
  	}
        
  	j = st_index;
  	n_filetypes = st_n_filetypes;
  	n_read_lists = total_blks_to_read/MAX_ARRAY_SIZE;
  	extra_blks = total_blks_to_read%MAX_ARRAY_SIZE;
  	
  	mem_offsets = (size_t)buf;
  	mem_lengths = 0;
  	
  	/* if at least one full readlist, allocate file arrays
  	   at max array size and don't free until very end */
  	if (n_read_lists) {
  	    file_offsets = (int64_t*)ADIOI_Malloc(MAX_ARRAY_SIZE*
  						  sizeof(int64_t));
  	    file_lengths = (uint64_t*)ADIOI_Malloc(MAX_ARRAY_SIZE*
  						  sizeof(uint64_t));
  	}
  	/* if there's no full readlist allocate file arrays according
  	   to needed size (extra_blks) */
  	else {
  	    file_offsets = (int64_t*)ADIOI_Malloc(extra_blks*
  						  sizeof(int64_t));
  	    file_lengths = (uint64_t*)ADIOI_Malloc(extra_blks*
  						  sizeof(uint64_t));
  	}
  	
  	/* for file arrays that are of MAX_ARRAY_SIZE, build arrays */
  	for (i=0; i<n_read_lists; i++) {
  	    file_list_count = MAX_ARRAY_SIZE;
  	    if(!i) {
  	        file_offsets[0] = offset;
  		file_lengths[0] = st_frd_size;
  		mem_lengths = st_frd_size;
  	    }
  	    for (k=0; k<MAX_ARRAY_SIZE; k++) {
  	        if (i || k) {
  		    file_offsets[k] = disp + 
  			((ADIO_Offset)n_filetypes)*filetype_extent
  		      + flat_file->indices[j];
  		    file_lengths[k] = flat_file->blocklens[j];
  		    mem_lengths += file_lengths[k];
  		}
  		if (j<(flat_file->count - 1)) j++;
  		else {
  		    j = 0;
  		    n_filetypes++;
  		}
  	    } /* for (k=0; k<MAX_ARRAY_SIZE; k++) */
  	    /* --END ERROR HANDLING-- */
  #ifdef ADIOI_MPE_LOGGING
              MPE_Log_event( ADIOI_MPE_read_a, 0, NULL );
  #endif
  	    NO_STALE(err_flag, fd, zoidfs_obj_ptr,
  			    zoidfs_read(zoidfs_obj_ptr,
  				    1, buf, &mem_lengths,
  				    file_list_count,
  				    file_offsets, file_lengths, ZOIDFS_NO_OP_HINT));
  #ifdef ADIOI_MPE_LOGGING
              MPE_Log_event( ADIOI_MPE_read_b, 0, NULL );
  #endif
  	    /* --BEGIN ERROR HANDLING-- */
  	    if (err_flag != ZFS_OK) {
  		*error_code = MPIO_Err_create_code(MPI_SUCCESS,
  						   MPIR_ERR_RECOVERABLE,
  						   myname, __LINE__,
  						   ADIOI_ZOIDFS_error_convert(err_flag),
  						   "Error in zoidfs_read", 0);
  		goto error_state;
  	    }
  	    /* --END ERROR HANDING-- */
  	    total_bytes_read += mem_lengths;
  
  	    mem_offsets += mem_lengths;
  	    mem_lengths = 0;
  	} /* for (i=0; i<n_read_lists; i++) */
  
  	/* for file arrays smaller than MAX_ARRAY_SIZE (last read_list call) */
  	if (extra_blks) {
  	    file_list_count = extra_blks;
  	    if(!i) {
  	        file_offsets[0] = offset;
  		file_lengths[0] = ADIOI_MIN(st_frd_size, bufsize);
  	    }
  	    for (k=0; k<extra_blks; k++) {
  	        if(i || k) {
  		    file_offsets[k] = disp + 
  			((ADIO_Offset)n_filetypes)*filetype_extent +
  			flat_file->indices[j];
  		    if (k == (extra_blks - 1)) {
  		        file_lengths[k] = bufsize - mem_lengths
  			  - mem_offsets + (size_t)buf;
  		    }
  		    else file_lengths[k] = flat_file->blocklens[j];
  		} /* if(i || k) */
  		mem_lengths += file_lengths[k];
  		if (j<(flat_file->count - 1)) j++;
  		else {
  		    j = 0;
  		    n_filetypes++;
  		}
  	    } /* for (k=0; k<extra_blks; k++) */
  #ifdef ADIOI_MPE_LOGGING
              MPE_Log_event( ADIOI_MPE_read_a, 0, NULL );
  #endif
  	    NO_STALE(err_flag, fd, zoidfs_obj_ptr,
  			    zoidfs_read(zoidfs_obj_ptr, 1,
  				   (void **)&mem_offsets,
  				   &mem_lengths,
  				   file_list_count,
  				   file_offsets, file_lengths, ZOIDFS_NO_OP_HINT));
  #ifdef ADIOI_MPE_LOGGING
              MPE_Log_event( ADIOI_MPE_read_b, 0, NULL );
  #endif
  	    /* --BEGIN ERROR HANDLING-- */
  	    if (err_flag != 0) {
  		*error_code = MPIO_Err_create_code(MPI_SUCCESS,
  						   MPIR_ERR_RECOVERABLE,
  						   myname, __LINE__,
  						   ADIOI_ZOIDFS_error_convert(err_flag),
  						   "Error in zoidfs_read", 0);		
  		goto error_state;
  	    }
  	    /* --END ERROR HANDLING-- */
  	    total_bytes_read += mem_lengths;
  	}
      }
      else {
  /* noncontiguous in memory as well as in file */
        
  	flat_buf = ADIOI_Flatten_and_find(datatype);
  
  	size_read = 0;
  	n_filetypes = st_n_filetypes;
  	frd_size = st_frd_size;
  	brd_size = flat_buf->blocklens[0];
  	buf_count = 0;
  	start_mem_offset = 0;
  	start_k = k = 0;
  	start_j = st_index;
  	max_mem_list = 0;
  	max_file_list = 0;
  
  	/* run through and file max_file_list and max_mem_list so that you 
  	   can allocate the file and memory arrays less than MAX_ARRAY_SIZE
  	   if possible */
  
  	while (size_read < bufsize) {
  	    k = start_k;
  	    new_buffer_read = 0;
  	    mem_list_count = 0;
  	    while ((mem_list_count < MAX_ARRAY_SIZE) && 
  		   (new_buffer_read < bufsize-size_read)) {
  	        /* find mem_list_count and file_list_count such that both are
  		   less than MAX_ARRAY_SIZE, the sum of their lengths are
  		   equal, and the sum of all the data read and data to be
  		   read in the next immediate read list is less than
  		   bufsize */
  	        if(mem_list_count) {
  		    if((new_buffer_read + flat_buf->blocklens[k] + 
  			size_read) > bufsize) {
  		        end_brd_size = new_buffer_read + 
  			    flat_buf->blocklens[k] - (bufsize - size_read);
  			new_buffer_read = bufsize - size_read;
  		    }
  		    else {
  		        new_buffer_read += flat_buf->blocklens[k];
  			end_brd_size = flat_buf->blocklens[k];
  		    }
  		}
  		else {
  		    if (brd_size > (bufsize - size_read)) {
  		        new_buffer_read = bufsize - size_read;
  			brd_size = new_buffer_read;
  		    }
  		    else new_buffer_read = brd_size;
  		}
  		mem_list_count++;
  		k = (k + 1)%flat_buf->count;
  	     } /* while ((mem_list_count < MAX_ARRAY_SIZE) && 
  	       (new_buffer_read < bufsize-size_read)) */
  	    j = start_j;
  	    new_file_read = 0;
  	    file_list_count = 0;
  	    while ((file_list_count < MAX_ARRAY_SIZE) && 
  		   (new_file_read < new_buffer_read)) {
  	        if(file_list_count) {
  		    if((new_file_read + flat_file->blocklens[j]) > 
  		       new_buffer_read) {
  		        end_frd_size = new_buffer_read - new_file_read;
  			new_file_read = new_buffer_read;
  			j--;
  		    }
  		    else {
  		        new_file_read += flat_file->blocklens[j];
  			end_frd_size = flat_file->blocklens[j];
  		    }
  		}
  		else {
  		    if (frd_size > new_buffer_read) {
  		        new_file_read = new_buffer_read;
  			frd_size = new_file_read;
  		    }
  		    else new_file_read = frd_size;
  		}
  		file_list_count++;
  		if (j < (flat_file->count - 1)) j++;
  		else j = 0;
  		
  		k = start_k;
  		if ((new_file_read < new_buffer_read) && 
  		    (file_list_count == MAX_ARRAY_SIZE)) {
  		    new_buffer_read = 0;
  		    mem_list_count = 0;
  		    while (new_buffer_read < new_file_read) {
  		        if(mem_list_count) {
  			    if((new_buffer_read + flat_buf->blocklens[k]) >
  			       new_file_read) {
  			        end_brd_size = new_file_read - new_buffer_read;
  				new_buffer_read = new_file_read;
  				k--;
  			    }
  			    else {
  			        new_buffer_read += flat_buf->blocklens[k];
  				end_brd_size = flat_buf->blocklens[k];
  			    }
  			}
  			else {
  			    new_buffer_read = brd_size;
  			    if (brd_size > (bufsize - size_read)) {
  			        new_buffer_read = bufsize - size_read;
  				brd_size = new_buffer_read;
  			    }
  			}
  			mem_list_count++;
  			k = (k + 1)%flat_buf->count;
  		    } /* while (new_buffer_read < new_file_read) */
  		} /* if ((new_file_read < new_buffer_read) && (file_list_count
  		     == MAX_ARRAY_SIZE)) */
  	    } /* while ((mem_list_count < MAX_ARRAY_SIZE) && 
  		 (new_buffer_read < bufsize-size_read)) */
  
  	    /*  fakes filling the readlist arrays of lengths found above  */
  	    k = start_k;
  	    j = start_j;
  	    for (i=0; i<mem_list_count; i++) {	     
  		if(i) {
  		    if (i == (mem_list_count - 1)) {
  			if (flat_buf->blocklens[k] == end_brd_size)
  			    brd_size = flat_buf->blocklens[(k+1)%
  							  flat_buf->count];
  			else {
  			    brd_size = flat_buf->blocklens[k] - end_brd_size;
  			    k--;
  			    buf_count--;
  			}
  		    }
  		}
  		buf_count++;
  		k = (k + 1)%flat_buf->count;
  	    } /* for (i=0; i<mem_list_count; i++) */
  	    for (i=0; i<file_list_count; i++) {
  		if (i) {
  		    if (i == (file_list_count - 1)) {
  			if (flat_file->blocklens[j] == end_frd_size)
  			    frd_size = flat_file->blocklens[(j+1)%
  							  flat_file->count];   
  			else {
  			    frd_size = flat_file->blocklens[j] - end_frd_size;
  			    j--;
  			}
  		    }
  		}
  		if (j < flat_file->count - 1) j++;
  		else {
  		    j = 0;
  		    n_filetypes++;
  		}
  	    } /* for (i=0; i<file_list_count; i++) */
  	    size_read += new_buffer_read;
  	    start_k = k;
  	    start_j = j;
  	    if (max_mem_list < mem_list_count)
  	        max_mem_list = mem_list_count;
  	    if (max_file_list < file_list_count)
  	        max_file_list = file_list_count;
  	} /* while (size_read < bufsize) */
  
  	/* one last check before we actually carry out the operation:
  	 * this code has hard-to-fix bugs when a noncontiguous file type has
  	 * such large pieces that the sum of the lengths of the memory type is
  	 * not larger than one of those pieces (and vice versa for large memory
  	 * types and many pices of file types.  In these cases, give up and
  	 * fall back to naive reads and writes.  The testphdf5 test created a
  	 * type with two very large memory regions and 600 very small file
  	 * regions.  The same test also created a type with one very large file
  	 * region and many (700) very small memory regions.  both cases caused
  	 * problems for this code */
  
  	if ( ( (file_list_count == 1) && 
  		    (new_file_read < flat_file->blocklens[0] ) ) ||
  		((mem_list_count == 1) && 
  		    (new_buffer_read < flat_buf->blocklens[0]) ) ||
  		((file_list_count == MAX_ARRAY_SIZE) && 
  		    (new_file_read < flat_buf->blocklens[0]) ) ||
  		( (mem_list_count == MAX_ARRAY_SIZE) &&
  		    (new_buffer_read < flat_file->blocklens[0])) )
  	{
  
  	    ADIOI_Delete_flattened(datatype);
  	    ADIOI_GEN_ReadStrided_naive(fd, buf, count, datatype,
  		    file_ptr_type, initial_off, status, error_code);
  	    return;
  	}
  
  	mem_offsets = (void *)ADIOI_Malloc(max_mem_list*sizeof(void *));
  	mem_lengths = (size_t*)ADIOI_Malloc(max_mem_list*sizeof(size_t));
  	file_offsets = (uint64_t *)ADIOI_Malloc(max_file_list*sizeof(uint64_t));
  	file_lengths = (uint64_t *)ADIOI_Malloc(max_file_list*sizeof(uint64_t));
  	    
  	size_read = 0;
  	n_filetypes = st_n_filetypes;
  	frd_size = st_frd_size;
  	brd_size = flat_buf->blocklens[0];
  	buf_count = 0;
  	start_mem_offset = 0;
  	start_k = k = 0;
  	start_j = st_index;
  
  	/*  this section calculates mem_list_count and file_list_count
  	    and also finds the possibly odd sized last array elements
  	    in new_frd_size and new_brd_size  */
  	
  	while (size_read < bufsize) {
  	    k = start_k;
  	    new_buffer_read = 0;
  	    mem_list_count = 0;
  	    while ((mem_list_count < MAX_ARRAY_SIZE) && 
  		   (new_buffer_read < bufsize-size_read)) {
  	        /* find mem_list_count and file_list_count such that both are
  		   less than MAX_ARRAY_SIZE, the sum of their lengths are
  		   equal, and the sum of all the data read and data to be
  		   read in the next immediate read list is less than
  		   bufsize */
  	        if(mem_list_count) {
  		    if((new_buffer_read + flat_buf->blocklens[k] + 
  			size_read) > bufsize) {
  		        end_brd_size = new_buffer_read + 
  			    flat_buf->blocklens[k] - (bufsize - size_read);
  			new_buffer_read = bufsize - size_read;
  		    }
  		    else {
  		        new_buffer_read += flat_buf->blocklens[k];
  			end_brd_size = flat_buf->blocklens[k];
  		    }
  		}
  		else {
  		    if (brd_size > (bufsize - size_read)) {
  		        new_buffer_read = bufsize - size_read;
  			brd_size = new_buffer_read;
  		    }
  		    else new_buffer_read = brd_size;
  		}
  		mem_list_count++;
  		k = (k + 1)%flat_buf->count;
  	     } /* while ((mem_list_count < MAX_ARRAY_SIZE) && 
  	       (new_buffer_read < bufsize-size_read)) */
  	    j = start_j;
  	    new_file_read = 0;
  	    file_list_count = 0;
  	    while ((file_list_count < MAX_ARRAY_SIZE) && 
  		   (new_file_read < new_buffer_read)) {
  	        if(file_list_count) {
  		    if((new_file_read + flat_file->blocklens[j]) > 
  		       new_buffer_read) {
  		        end_frd_size = new_buffer_read - new_file_read;
  			new_file_read = new_buffer_read;
  			j--;
  		    }
  		    else {
  		        new_file_read += flat_file->blocklens[j];
  			end_frd_size = flat_file->blocklens[j];
  		    }
  		}
  		else {
  		    if (frd_size > new_buffer_read) {
  		        new_file_read = new_buffer_read;
  			frd_size = new_file_read;
  		    }
  		    else new_file_read = frd_size;
  		}
  		file_list_count++;
  		if (j < (flat_file->count - 1)) j++;
  		else j = 0;
  		
  		k = start_k;
  		if ((new_file_read < new_buffer_read) && 
  		    (file_list_count == MAX_ARRAY_SIZE)) {
  		    new_buffer_read = 0;
  		    mem_list_count = 0;
  		    while (new_buffer_read < new_file_read) {
  		        if(mem_list_count) {
  			    if((new_buffer_read + flat_buf->blocklens[k]) >
  			       new_file_read) {
  			        end_brd_size = new_file_read - new_buffer_read;
  				new_buffer_read = new_file_read;
  				k--;
  			    }
  			    else {
  			        new_buffer_read += flat_buf->blocklens[k];
  				end_brd_size = flat_buf->blocklens[k];
  			    }
  			}
  			else {
  			    new_buffer_read = brd_size;
  			    if (brd_size > (bufsize - size_read)) {
  			        new_buffer_read = bufsize - size_read;
  				brd_size = new_buffer_read;
  			    }
  			}
  			mem_list_count++;
  			k = (k + 1)%flat_buf->count;
  		    } /* while (new_buffer_read < new_file_read) */
  		} /* if ((new_file_read < new_buffer_read) && (file_list_count
  		     == MAX_ARRAY_SIZE)) */
  	    } /* while ((mem_list_count < MAX_ARRAY_SIZE) && 
  		 (new_buffer_read < bufsize-size_read)) */
  
  	    /*  fills the allocated readlist arrays  */
  	    k = start_k;
  	    j = start_j;
  	    for (i=0; i<mem_list_count; i++) {	     
  	        mem_offsets[i] = buf + 
  			buftype_extent* (buf_count/flat_buf->count) +
  					 flat_buf->indices[k];
  		if(!i) {
  		    mem_lengths[0] = brd_size;
  		    mem_offsets[0] += flat_buf->blocklens[k] - brd_size;
  		}
  		else {
  		    if (i == (mem_list_count - 1)) {
  		        mem_lengths[i] = end_brd_size;
  			if (flat_buf->blocklens[k] == end_brd_size)
  			    brd_size = flat_buf->blocklens[(k+1)%
  							  flat_buf->count];
  			else {
  			    brd_size = flat_buf->blocklens[k] - end_brd_size;
  			    k--;
  			    buf_count--;
  			}
  		    }
  		    else {
  		        mem_lengths[i] = flat_buf->blocklens[k];
  		    }
  		}
  		buf_count++;
  		k = (k + 1)%flat_buf->count;
  	    } /* for (i=0; i<mem_list_count; i++) */
  	    for (i=0; i<file_list_count; i++) {
  	        file_offsets[i] = disp + flat_file->indices[j] + 
  		    ((ADIO_Offset)n_filetypes) * filetype_extent;
  	        if (!i) {
  		    file_lengths[0] = frd_size;
  		    file_offsets[0] += flat_file->blocklens[j] - frd_size;
  		}
  		else {
  		    if (i == (file_list_count - 1)) {
  		        file_lengths[i] = end_frd_size;
  			if (flat_file->blocklens[j] == end_frd_size)
  			    frd_size = flat_file->blocklens[(j+1)%
  							  flat_file->count];   
  			else {
  			    frd_size = flat_file->blocklens[j] - end_frd_size;
  			    j--;
  			}
  		    }
  		    else file_lengths[i] = flat_file->blocklens[j];
  		}
  		if (j < flat_file->count - 1) j++;
  		else {
  		    j = 0;
  		    n_filetypes++;
  		}
  	    } /* for (i=0; i<file_list_count; i++) */
  
  #ifdef ADIOI_MPE_LOGGING
              MPE_Log_event( ADIOI_MPE_read_a, 0, NULL );
  #endif
  	    NO_STALE(err_flag, fd, zoidfs_obj_ptr,
  			    zoidfs_read(zoidfs_obj_ptr,
  				    mem_list_count, mem_offsets, mem_lengths,
  				    file_list_count,
  				    file_offsets, file_lengths, ZOIDFS_NO_OP_HINT));
  #ifdef ADIOI_MPE_LOGGING
              MPE_Log_event( ADIOI_MPE_read_b, 0, NULL );
  #endif
  	    /* --BEGIN ERROR HANDLING-- */
  	    if (err_flag != ZFS_OK) {
  		*error_code = MPIO_Err_create_code(MPI_SUCCESS,
  						   MPIR_ERR_RECOVERABLE,
  						   myname, __LINE__,
  						   ADIOI_ZOIDFS_error_convert(err_flag),
  						   "Error in zoidfs_read", 0);
  	    }
  	    /* --END ERROR HANDLING-- */
  	    size_read += new_buffer_read;
  	    total_bytes_read += new_buffer_read; /* XXX: is this right? */
  	    start_k = k;
  	    start_j = j;
  	} /* while (size_read < bufsize) */
  	ADIOI_Free(mem_offsets);
  	ADIOI_Free(mem_lengths);
      }
      /* Other ADIO routines will convert absolute bytes into counts of datatypes */
      /* when incrementing fp_ind, need to also take into account the file type:
       * consider an N-element 1-d subarray with a lb and ub: ( |---xxxxx-----|
       * if we wrote N elements, offset needs to point at beginning of type, not
       * at empty region at offset N+1) 
       *
       * As we discussed on mpich-discuss in may/june 2009, the code below might
       * look wierd, but by putting fp_ind at the last byte written, the next
       * time we run through the strided code we'll update the fp_ind to the
       * right location. */
      if (file_ptr_type == ADIO_INDIVIDUAL) {
  	fd->fp_ind = file_offsets[file_list_count-1]+
  	    file_lengths[file_list_count-1];
      }
      
      ADIOI_Free(file_offsets);
      ADIOI_Free(file_lengths);
      
      if (err_flag == 0) *error_code = MPI_SUCCESS;
  
  error_state:
      fd->fp_sys_posn = -1;   /* set it to null. */
  
  #ifdef HAVE_STATUS_SET_BYTES
      MPIR_Status_set_bytes(status, datatype, bufsize);
      /* This is a temporary way of filling in status. The right way is to 
         keep track of how much data was actually read and placed in buf 
         by ADIOI_BUFFERED_READ. */
  #endif
      
      if (!buftype_is_contig) ADIOI_Delete_flattened(datatype);
  }
  
  