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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* 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://www.hdfgroup.org/licenses. *
* 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
* significant 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 laid 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
*
*-------------------------------------------------------------------------
*/
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, "can'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
* significant 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 laid 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
*
*-------------------------------------------------------------------------
*/
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
* significant 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 laid 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
*
*-------------------------------------------------------------------------
*/
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
* significant 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 laid 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
*
*-------------------------------------------------------------------------
*/
static herr_t
H5T__set_offset(const H5T_t *dt, size_t offset)
{
herr_t ret_value = SUCCEED; /* Return value */
FUNC_ENTER_PACKAGE
/* Check args */
assert(dt);
assert(H5T_STRING != dt->shared->type || 0 == offset);
assert(H5T_REFERENCE != dt->shared->type);
assert(H5T_OPAQUE != dt->shared->type);
assert(H5T_COMPOUND != dt->shared->type);
assert(!(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)
}
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