/src/hdf5/src/H5Toffset.c

Source
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * 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 LICENSE 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)

    /* 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)

    /* 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_COMPLEX)
            dt->shared->size = 2 * dt->shared->parent->shared->size;
        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)
}

Coverage Report

Created: 2026-02-23 06:05

Line	Count	Source
1		/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
2		* Copyright by The HDF Group. *
3		* All rights reserved. *
4		* *
5		* This file is part of HDF5. The full HDF5 copyright notice, including *
6		* terms governing use, modification, and redistribution, is contained in *
7		* the LICENSE file, which can be found at the root of the source code *
8		* distribution tree, or in https://www.hdfgroup.org/licenses. *
9		* If you do not have access to either file, you may request a copy from *
10		* help@hdfgroup.org. *
11		* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
12
13		/*
14		* Module Info: This module contains the functionality for setting & querying
15		* the datatype offset for the H5T interface.
16		*/
17
18		#include "H5Tmodule.h" /* This source code file is part of the H5T module */
19
20		#include "H5private.h" /* Generic Functions */
21		#include "H5Eprivate.h" /* Error handling */
22		#include "H5Iprivate.h" /* IDs */
23		#include "H5Tpkg.h" /* Datatypes */
24
25		/* Static local functions */
26		static herr_t H5T__set_offset(const H5T_t *dt, size_t offset);
27
28		/*-------------------------------------------------------------------------
29		* Function: H5Tget_offset
30		*
31		* Purpose: Retrieves the bit offset of the first significant bit. The
32		* significant bits of an atomic datum can be offset from the
33		* beginning of the memory for that datum by an amount of
34		* padding. The `offset' property specifies the number of bits
35		* of padding that appear to the "right of" the value. That is,
36		* if we have a 32-bit datum with 16-bits of precision having
37		* the value 0x1122 then it will be laid out in memory as (from
38		* small byte address toward larger byte addresses):
39		*
40		* Big Big Little Little
41		* Endian Endian Endian Endian
42		* offset=0 offset=16 offset=0 offset=16
43		*
44		* 0: [ pad] [0x11] [0x22] [ pad]
45		* 1: [ pad] [0x22] [0x11] [ pad]
46		* 2: [0x11] [ pad] [ pad] [0x22]
47		* 3: [0x22] [ pad] [ pad] [0x11]
48		*
49		* Return: Success: The offset (non-negative)
50		* Failure: Negative
51		*
52		*-------------------------------------------------------------------------
53		*/
54		int
55		H5Tget_offset(hid_t type_id)
56	0	{
57	0	H5T_t *dt;
58	0	int ret_value;
59
60	0	FUNC_ENTER_API(-1)
61
62		/* Check args */
63	0	if (NULL == (dt = (H5T_t *)H5I_object_verify(type_id, H5I_DATATYPE)))
64	0	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an atomic data type");
65
66		/* Get offset */
67	0	if ((ret_value = H5T_get_offset(dt)) < 0)
68	0	HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "can't get offset for specified datatype");
69
70	0	done:
71	0	FUNC_LEAVE_API(ret_value)
72	0	} /* end H5Tget_offset() */
73
74		/*-------------------------------------------------------------------------
75		* Function: H5T_get_offset
76		*
77		* Purpose: Retrieves the bit offset of the first significant bit. The
78		* significant bits of an atomic datum can be offset from the
79		* beginning of the memory for that datum by an amount of
80		* padding. The `offset' property specifies the number of bits
81		* of padding that appear to the "right of" the value. That is,
82		* if we have a 32-bit datum with 16-bits of precision having
83		* the value 0x1122 then it will be laid out in memory as (from
84		* small byte address toward larger byte addresses):
85		*
86		* Big Big Little Little
87		* Endian Endian Endian Endian
88		* offset=0 offset=16 offset=0 offset=16
89		*
90		* 0: [ pad] [0x11] [0x22] [ pad]
91		* 1: [ pad] [0x22] [0x11] [ pad]
92		* 2: [0x11] [ pad] [ pad] [0x22]
93		* 3: [0x22] [ pad] [ pad] [0x11]
94		*
95		* Return: Success: The offset (non-negative)
96		* Failure: Negative
97		*
98		*-------------------------------------------------------------------------
99		*/
100		int
101		H5T_get_offset(const H5T_t *dt)
102	0	{
103	0	int ret_value = -1; /* Return value */
104
105	0	FUNC_ENTER_NOAPI(-1)
106
107		/* Defer to parent*/
108	0	while (dt->shared->parent)
109	0	dt = dt->shared->parent;
110	0	if (!H5T_IS_ATOMIC(dt->shared))
111	0	HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "operation not defined for specified data type");
112
113		/* Offset */
114	0	ret_value = (int)dt->shared->u.atomic.offset;
115
116	0	done:
117	0	FUNC_LEAVE_NOAPI(ret_value)
118	0	} /* end H5T_get_offset() */
119
120		/*-------------------------------------------------------------------------
121		* Function: H5Tset_offset
122		*
123		* Purpose: Sets the bit offset of the first significant bit. The
124		* significant bits of an atomic datum can be offset from the
125		* beginning of the memory for that datum by an amount of
126		* padding. The `offset' property specifies the number of bits
127		* of padding that appear to the "right of" the value. That is,
128		* if we have a 32-bit datum with 16-bits of precision having
129		* the value 0x1122 then it will be laid out in memory as (from
130		* small byte address toward larger byte addresses):
131		*
132		* Big Big Little Little
133		* Endian Endian Endian Endian
134		* offset=0 offset=16 offset=0 offset=16
135		*
136		* 0: [ pad] [0x11] [0x22] [ pad]
137		* 1: [ pad] [0x22] [0x11] [ pad]
138		* 2: [0x11] [ pad] [ pad] [0x22]
139		* 3: [0x22] [ pad] [ pad] [0x11]
140		*
141		* If the offset is incremented then the total size is
142		* incremented also if necessary to prevent significant bits of
143		* the value from hanging over the edge of the data type.
144		*
145		* The offset of an H5T_STRING cannot be set to anything but
146		* zero.
147		*
148		* Return: Non-negative on success/Negative on failure
149		*
150		*-------------------------------------------------------------------------
151		*/
152		herr_t
153		H5Tset_offset(hid_t type_id, size_t offset)
154	0	{
155	0	H5T_t *dt;
156	0	herr_t ret_value = SUCCEED; /* Return value */
157
158	0	FUNC_ENTER_API(FAIL)
159
160		/* Check args */
161	0	if (NULL == (dt = (H5T_t *)H5I_object_verify(type_id, H5I_DATATYPE)))
162	0	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not an atomic data type");
163	0	if (H5T_STATE_TRANSIENT != dt->shared->state)
164	0	HGOTO_ERROR(H5E_ARGS, H5E_CANTINIT, FAIL, "data type is read-only");
165	0	if (H5T_STRING == dt->shared->type && offset != 0)
166	0	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "offset must be zero for this type");
167	0	if (H5T_ENUM == dt->shared->type && dt->shared->u.enumer.nmembs > 0)
168	0	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "operation not allowed after members are defined");
169	0	if (H5T_COMPOUND == dt->shared->type \|\| H5T_REFERENCE == dt->shared->type \|\|
170	0	H5T_OPAQUE == dt->shared->type)
171	0	HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "operation not defined for this datatype");
172
173		/* Do the real work */
174	0	if (H5T__set_offset(dt, offset) < 0)
175	0	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to set offset");
176
177	0	done:
178	0	FUNC_LEAVE_API(ret_value)
179	0	}
180
181		/*-------------------------------------------------------------------------
182		* Function: H5T__set_offset
183		*
184		* Purpose: Sets the bit offset of the first significant bit. The
185		* significant bits of an atomic datum can be offset from the
186		* beginning of the memory for that datum by an amount of
187		* padding. The `offset' property specifies the number of bits
188		* of padding that appear to the "right of" the value. That is,
189		* if we have a 32-bit datum with 16-bits of precision having
190		* the value 0x1122 then it will be laid out in memory as (from
191		* small byte address toward larger byte addresses):
192		*
193		* Big Big Little Little
194		* Endian Endian Endian Endian
195		* offset=0 offset=16 offset=0 offset=16
196		*
197		* 0: [ pad] [0x11] [0x22] [ pad]
198		* 1: [ pad] [0x22] [0x11] [ pad]
199		* 2: [0x11] [ pad] [ pad] [0x22]
200		* 3: [0x22] [ pad] [ pad] [0x11]
201		*
202		* If the offset is incremented then the total size is
203		* incremented also if necessary to prevent significant bits of
204		* the value from hanging over the edge of the data type.
205		*
206		* The offset of an H5T_STRING cannot be set to anything but
207		* zero.
208		*
209		* Return: Non-negative on success/Negative on failure
210		*
211		*-------------------------------------------------------------------------
212		*/
213		static herr_t
214		H5T__set_offset(const H5T_t *dt, size_t offset)
215	0	{
216	0	herr_t ret_value = SUCCEED; /* Return value */
217
218	0	FUNC_ENTER_PACKAGE
219
220		/* Check args */
221	0	assert(dt);
222	0	assert(H5T_STRING != dt->shared->type \|\| 0 == offset);
223	0	assert(H5T_REFERENCE != dt->shared->type);
224	0	assert(H5T_OPAQUE != dt->shared->type);
225	0	assert(H5T_COMPOUND != dt->shared->type);
226	0	assert(!(H5T_ENUM == dt->shared->type && 0 == dt->shared->u.enumer.nmembs));
227
228	0	if (dt->shared->parent) {
229	0	if (H5T__set_offset(dt->shared->parent, offset) < 0)
230	0	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to set offset for base type");
231
232		/* Adjust size of datatype appropriately */
233	0	if (dt->shared->type == H5T_ARRAY)
234	0	dt->shared->size = dt->shared->parent->shared->size * dt->shared->u.array.nelem;
235	0	else if (dt->shared->type == H5T_COMPLEX)
236	0	dt->shared->size = 2 * dt->shared->parent->shared->size;
237	0	else if (dt->shared->type != H5T_VLEN)
238	0	dt->shared->size = dt->shared->parent->shared->size;
239	0	}
240	0	else {
241	0	if (offset + dt->shared->u.atomic.prec > 8 * dt->shared->size)
242	0	dt->shared->size = (offset + dt->shared->u.atomic.prec + 7) / 8;
243	0	dt->shared->u.atomic.offset = offset;
244	0	}
245
246	0	done:
247	0	FUNC_LEAVE_NOAPI(ret_value)
248	0	}