summaryrefslogtreecommitdiffstats
path: root/src/H5Tprecis.c
blob: 07b868e51a5c5b611ff4c3d69731b470eeafa44b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
 * 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://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 precision 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_precision(const H5T_t *dt, size_t prec);

/*-------------------------------------------------------------------------
 * Function:	H5Tget_precision
 *
 * Purpose:	Gets the precision of a datatype.  The precision is
 *		the number of significant bits which, unless padding is
 *		present, is 8 times larger than the value returned by
 *		H5Tget_size().
 *
 * Return:	Success:	Number of significant bits
 *
 *		Failure:	0 (all atomic types have at least one
 *				significant bit)
 *
 * Programmer:	Robb Matzke
 *		Wednesday, January  7, 1998
 *
 *-------------------------------------------------------------------------
 */
size_t
H5Tget_precision(hid_t type_id)
{
    H5T_t *dt;
    size_t ret_value;

    FUNC_ENTER_API(0)
    H5TRACE1("z", "i", type_id);

    /* Check args */
    if (NULL == (dt = (H5T_t *)H5I_object_verify(type_id, H5I_DATATYPE)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "not a datatype")

    /* Get precision */
    if ((ret_value = H5T_get_precision(dt)) == 0)
        HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, 0, "can't get precision for specified datatype")

done:
    FUNC_LEAVE_API(ret_value)
} /* end H5Tget_precision() */

/*-------------------------------------------------------------------------
 * Function:	H5T_get_precision
 *
 * Purpose:	Gets the precision of a datatype.  The precision is
 *		the number of significant bits which, unless padding is
 *		present, is 8 times larger than the value returned by
 *		H5Tget_size().
 *
 * Return:	Success:	Number of significant bits
 *		Failure:	0 (all atomic types have at least one
 *				significant bit)
 *
 * Programmer:	Quincey Koziol
 *		Wednesday, October 17, 2007
 *
 *-------------------------------------------------------------------------
 */
size_t
H5T_get_precision(const H5T_t *dt)
{
    size_t ret_value = 0; /* Return value */

    FUNC_ENTER_NOAPI(0)

    /* Defer to parent*/
    while (dt->shared->parent)
        dt = dt->shared->parent;
    if (!H5T_IS_ATOMIC(dt->shared))
        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, 0, "operation not defined for specified datatype")

    /* Precision */
    ret_value = dt->shared->u.atomic.prec;

done:
    FUNC_LEAVE_NOAPI(ret_value)
} /* end H5T_get_precision() */

/*-------------------------------------------------------------------------
 * Function:	H5Tset_precision
 *
 * Purpose:	Sets the precision of a datatype.  The precision is
 *		the number of significant bits which, unless padding is
 *		present, is 8 times larger than the value returned by
 *		H5Tget_size().
 *
 *		If the precision is increased then the offset is decreased
 *		and then the size is increased to insure that significant
 *		bits do not "hang over" the edge of the datatype.
 *
 *		The precision property of strings is read-only.
 *
 *		When decreasing the precision of a floating point type, set
 *		the locations and sizes of the sign, mantissa, and exponent
 *		fields first.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		Wednesday, January  7, 1998
 *
 *-------------------------------------------------------------------------
 */
herr_t
H5Tset_precision(hid_t type_id, size_t prec)
{
    H5T_t *dt        = NULL;
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_API(FAIL)
    H5TRACE2("e", "iz", type_id, prec);

    /* Check args */
    if (NULL == (dt = (H5T_t *)H5I_object_verify(type_id, H5I_DATATYPE)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a datatype")
    if (H5T_STATE_TRANSIENT != dt->shared->state)
        HGOTO_ERROR(H5E_ARGS, H5E_CANTSET, FAIL, "datatype is read-only")
    if (prec == 0)
        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "precision must be positive")
    if (H5T_ENUM == dt->shared->type && dt->shared->u.enumer.nmembs > 0)
        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "operation not allowed after members are defined")
    if (H5T_STRING == dt->shared->type)
        HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "precision for this type is read-only")
    if (H5T_COMPOUND == dt->shared->type || H5T_OPAQUE == dt->shared->type)
        HGOTO_ERROR(H5E_DATATYPE, H5E_UNSUPPORTED, FAIL, "operation not defined for specified datatype")

    /* Do the work */
    if (H5T__set_precision(dt, prec) < 0)
        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "unable to set precision")

done:
    FUNC_LEAVE_API(ret_value)
}

/*-------------------------------------------------------------------------
 * Function:	H5T__set_precision
 *
 * Purpose:	Sets the precision of a datatype.  The precision is
 *		the number of significant bits which, unless padding is
 *		present, is 8 times larger than the value returned by
 *		H5Tget_size().
 *
 *		If the precision is increased then the offset is decreased
 *		and then the size is increased to insure that significant
 *		bits do not "hang over" the edge of the datatype.
 *
 *		The precision property of strings is read-only.
 *
 *		When decreasing the precision of a floating point type, set
 *		the locations and sizes of the sign, mantissa, and exponent
 *		fields first.
 *
 * Return:	Non-negative on success/Negative on failure
 *
 * Programmer:	Robb Matzke
 *		Wednesday, January  7, 1998
 *
 *-------------------------------------------------------------------------
 */
static herr_t
H5T__set_precision(const H5T_t *dt, size_t prec)
{
    size_t offset, size;
    herr_t ret_value = SUCCEED; /* Return value */

    FUNC_ENTER_STATIC

    /* Check args */
    HDassert(dt);
    HDassert(prec > 0);
    HDassert(H5T_OPAQUE != dt->shared->type);
    HDassert(H5T_COMPOUND != dt->shared->type);
    HDassert(H5T_STRING != dt->shared->type);
    HDassert(!(H5T_ENUM == dt->shared->type && 0 == dt->shared->u.enumer.nmembs));

    if (dt->shared->parent) {
        if (H5T__set_precision(dt->shared->parent, prec) < 0)
            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTSET, FAIL, "unable to set precision 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 (H5T_IS_ATOMIC(dt->shared)) {
            /* Adjust the offset and size */
            offset = dt->shared->u.atomic.offset;
            size   = dt->shared->size;
            if (prec > 8 * size)
                offset = 0;
            else if (offset + prec > 8 * size)
                offset = 8 * size - prec;
            if (prec > 8 * size)
                size = (prec + 7) / 8;

            /* Check that things are still kosher */
            switch (dt->shared->type) {
                case H5T_INTEGER:
                case H5T_TIME:
                case H5T_BITFIELD:
                    /* nothing to check */
                    break;

                case H5T_FLOAT:
                    /*
                     * The sign, mantissa, and exponent fields should be adjusted
                     * first when decreasing the precision of a floating point
                     * type.
                     */
                    if (dt->shared->u.atomic.u.f.sign >= prec + offset ||
                        dt->shared->u.atomic.u.f.epos + dt->shared->u.atomic.u.f.esize > prec + offset ||
                        dt->shared->u.atomic.u.f.mpos + dt->shared->u.atomic.u.f.msize > prec + offset)
                        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL,
                                    "adjust sign, mantissa, and exponent fields first")
                    break;

                case H5T_NO_CLASS:
                case H5T_STRING:
                case H5T_OPAQUE:
                case H5T_COMPOUND:
                case H5T_REFERENCE:
                case H5T_ENUM:
                case H5T_VLEN:
                case H5T_ARRAY:
                case H5T_NCLASSES:
                default:
                    HGOTO_ERROR(H5E_ARGS, H5E_UNSUPPORTED, FAIL, "operation not defined for datatype class")
            } /* end switch */

            /* Commit */
            dt->shared->size            = size;
            dt->shared->u.atomic.offset = offset;
            dt->shared->u.atomic.prec   = prec;
        } /* end if */
        else
            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "operation not defined for specified datatype")
    } /* end else */

done:
    FUNC_LEAVE_NOAPI(ret_value)
}