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 COPYING file, which can be found at the root of the source code       *
   * distribution tree, or in https://support.hdfgroup.org/ftp/HDF5/releases.  *
   * If you do not have access to either file, you may request a copy from     *
   * help@hdfgroup.org.                                                        *
   * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
  
  /*
   * Module Info: This module contains the functionality for setting & querying
   *      the datatype offset for the H5T interface.
   */
  
  #include "H5Tmodule.h"          /* This source code file is part of the H5T module */
  
  
  #include "H5private.h"		/* Generic Functions			*/
  #include "H5Eprivate.h"		/* Error handling		  	*/
  #include "H5Iprivate.h"		/* IDs			  		*/
  #include "H5Tpkg.h"		/* Datatypes				*/
  
  /* Static local functions */
  static herr_t H5T_set_offset(const H5T_t *dt, size_t offset);
  
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5Tget_offset
   *
   * Purpose:	Retrieves the bit offset of the first significant bit.	The
   *		signficant bits of an atomic datum can be offset from the
   *		beginning of the memory for that datum by an amount of
   *		padding. The `offset' property specifies the number of bits
   *		of padding that appear to the "right of" the value.  That is,
   *		if we have a 32-bit datum with 16-bits of precision having
   *		the value 0x1122 then it will be layed out in memory as (from
   *		small byte address toward larger byte addresses):
   *
   *		    Big	     Big       Little	Little
   *		    Endian   Endian    Endian	Endian
   *		    offset=0 offset=16 offset=0 offset=16
   *
   *		0:  [ pad]   [0x11]    [0x22]	[ pad]
   *		1:  [ pad]   [0x22]    [0x11]	[ pad]
   *		2:  [0x11]   [ pad]    [ pad]	[0x22]
   *		3:  [0x22]   [ pad]    [ pad]	[0x11]
   *
   * Return:	Success:	The offset (non-negative)
   *		Failure:	Negative
   *
   * Programmer:	Robb Matzke
   *		Wednesday, January  7, 1998
   *
   *-------------------------------------------------------------------------
   */
  int
  H5Tget_offset(hid_t type_id)
  {
      H5T_t	*dt;
      int	ret_value;
  
      FUNC_ENTER_API(-1)
      H5TRACE1("Is", "i", type_id);
  
      /* Check args */
      if(NULL == (dt = (H5T_t *)H5I_object_verify(type_id,H5I_DATATYPE)))
  	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an atomic data type")
  
      /* Get offset */
      if((ret_value = H5T_get_offset(dt)) < 0)
  	HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "cant't get offset for specified datatype")
  
  done:
      FUNC_LEAVE_API(ret_value)
  } /* end H5Tget_offset() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5T_get_offset
   *
   * Purpose:	Retrieves the bit offset of the first significant bit.	The
   *		signficant bits of an atomic datum can be offset from the
   *		beginning of the memory for that datum by an amount of
   *		padding. The `offset' property specifies the number of bits
   *		of padding that appear to the "right of" the value.  That is,
   *		if we have a 32-bit datum with 16-bits of precision having
   *		the value 0x1122 then it will be layed out in memory as (from
   *		small byte address toward larger byte addresses):
   *
   *		    Big	     Big       Little	Little
   *		    Endian   Endian    Endian	Endian
   *		    offset=0 offset=16 offset=0 offset=16
   *
   *		0:  [ pad]   [0x11]    [0x22]	[ pad]
   *		1:  [ pad]   [0x22]    [0x11]	[ pad]
   *		2:  [0x11]   [ pad]    [ pad]	[0x22]
   *		3:  [0x22]   [ pad]    [ pad]	[0x11]
   *
   * Return:	Success:	The offset (non-negative)
   *		Failure:	Negative
   *
   * Programmer:	Quincey Koziol
   *		Wednesday, October 17, 2007
   *
   *-------------------------------------------------------------------------
   */
  int
  H5T_get_offset(const H5T_t *dt)
  {
      int	ret_value = -1;         /* Return value */
  
      FUNC_ENTER_NOAPI(-1)
  
      /* Defer to parent*/
      while(dt->shared->parent)
          dt = dt->shared->parent;
      if(!H5T_IS_ATOMIC(dt->shared))
  	HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "operation not defined for specified data type")
  
      /* Offset */
      ret_value = (int)dt->shared->u.atomic.offset;
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  } /* end H5T_get_offset() */
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5Tset_offset
   *
   * Purpose:	Sets the bit offset of the first significant bit.  The
   *		signficant bits of an atomic datum can be offset from the
   *		beginning of the memory for that datum by an amount of
   *		padding. The `offset' property specifies the number of bits
   *		of padding that appear to the "right of" the value.  That is,
   *		if we have a 32-bit datum with 16-bits of precision having
   *		the value 0x1122 then it will be layed out in memory as (from
   *		small byte address toward larger byte addresses):
   *
   *		    Big	     Big       Little	Little
   *		    Endian   Endian    Endian	Endian
   *		    offset=0 offset=16 offset=0 offset=16
   *
   *		0:  [ pad]   [0x11]    [0x22]	[ pad]
   *		1:  [ pad]   [0x22]    [0x11]	[ pad]
   *		2:  [0x11]   [ pad]    [ pad]	[0x22]
   *		3:  [0x22]   [ pad]    [ pad]	[0x11]
   *
   *		If the offset is incremented then the total size is
   *		incremented also if necessary to prevent significant bits of
   *		the value from hanging over the edge of the data type.
   *
   *		The offset of an H5T_STRING cannot be set to anything but
   *		zero.
   *
   * Return:	Non-negative on success/Negative on failure
   *
   * Programmer:	Robb Matzke
   *		Wednesday, January  7, 1998
   *
   * Modifications:
   * 	Robb Matzke, 22 Dec 1998
   *	Moved real work to a private function.
   *
   *-------------------------------------------------------------------------
   */
  herr_t
  H5Tset_offset(hid_t type_id, size_t offset)
  {
      H5T_t	*dt;
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_API(FAIL)
      H5TRACE2("e", "iz", type_id, offset);
  
      /* Check args */
      if (NULL == (dt = (H5T_t *)H5I_object_verify(type_id,H5I_DATATYPE)))
  	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an atomic data type")
      if (H5T_STATE_TRANSIENT!=dt->shared->state)
  	HGOTO_ERROR(H5E_ARGS, H5E_CANTINIT, FAIL, "data type is read-only")
      if (H5T_STRING == dt->shared->type && offset != 0)
  	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "offset must be zero for this type")
      if (H5T_ENUM==dt->shared->type && dt->shared->u.enumer.nmembs>0)
  	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "operation not allowed after members are defined")
      if (H5T_COMPOUND==dt->shared->type || H5T_REFERENCE==dt->shared->type || H5T_OPAQUE==dt->shared->type)
  	HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "operation not defined for this datatype")
  
      /* Do the real work */
      if (H5T_set_offset(dt, offset)<0)
  	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to set offset")
  
  done:
      FUNC_LEAVE_API(ret_value)
  }
  
  
  /*-------------------------------------------------------------------------
   * Function:	H5T_set_offset
   *
   * Purpose:	Sets the bit offset of the first significant bit.  The
   *		signficant bits of an atomic datum can be offset from the
   *		beginning of the memory for that datum by an amount of
   *		padding. The `offset' property specifies the number of bits
   *		of padding that appear to the "right of" the value.  That is,
   *		if we have a 32-bit datum with 16-bits of precision having
   *		the value 0x1122 then it will be layed out in memory as (from
   *		small byte address toward larger byte addresses):
   *
   *		    Big	     Big       Little	Little
   *		    Endian   Endian    Endian	Endian
   *		    offset=0 offset=16 offset=0 offset=16
   *
   *		0:  [ pad]   [0x11]    [0x22]	[ pad]
   *		1:  [ pad]   [0x22]    [0x11]	[ pad]
   *		2:  [0x11]   [ pad]    [ pad]	[0x22]
   *		3:  [0x22]   [ pad]    [ pad]	[0x11]
   *
   *		If the offset is incremented then the total size is
   *		incremented also if necessary to prevent significant bits of
   *		the value from hanging over the edge of the data type.
   *
   *		The offset of an H5T_STRING cannot be set to anything but
   *		zero.
   *
   * Return:	Non-negative on success/Negative on failure
   *
   * Programmer:	Robb Matzke
   *		Wednesday, January  7, 1998
   *
   * Modifications:
   * 	Robb Matzke, 22 Dec 1998
   *	Also works for derived data types.
   *
   *-------------------------------------------------------------------------
   */
  static herr_t
  H5T_set_offset(const H5T_t *dt, size_t offset)
  {
      herr_t      ret_value=SUCCEED;       /* Return value */
  
      FUNC_ENTER_NOAPI(FAIL)
  
      /* Check args */
      HDassert(dt);
      HDassert(H5T_STRING!=dt->shared->type || 0==offset);
      HDassert(H5T_REFERENCE!=dt->shared->type);
      HDassert(H5T_OPAQUE!=dt->shared->type);
      HDassert(H5T_COMPOUND!=dt->shared->type);
      HDassert(!(H5T_ENUM==dt->shared->type && 0==dt->shared->u.enumer.nmembs));
  
      if (dt->shared->parent) {
  	if (H5T_set_offset(dt->shared->parent, offset)<0)
  	    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to set offset for base type")
  
          /* Adjust size of datatype appropriately */
          if(dt->shared->type==H5T_ARRAY)
              dt->shared->size = dt->shared->parent->shared->size * dt->shared->u.array.nelem;
          else if(dt->shared->type!=H5T_VLEN)
              dt->shared->size = dt->shared->parent->shared->size;
      } else {
          if (offset+dt->shared->u.atomic.prec > 8*dt->shared->size)
              dt->shared->size = (offset + dt->shared->u.atomic.prec + 7) / 8;
          dt->shared->u.atomic.offset = offset;
      }
  
  done:
      FUNC_LEAVE_NOAPI(ret_value)
  }
  
  