1 /* IEEE floating point support declarations, for GDB, the GNU Debugger.
2 Copyright (C) 1991-2023 Free Software Foundation, Inc.
3
4 This file is part of GDB.
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */
19
20 #if !defined (FLOATFORMAT_H)
21 #define FLOATFORMAT_H 1
22
23 #include "ansidecl.h"
24
25 #ifdef __cplusplus
26 extern "C" {
27 #endif
28
29 /* A floatformat consists of a sign bit, an exponent and a mantissa. Once the
30 bytes are concatenated according to the byteorder flag, then each of those
31 fields is contiguous. We number the bits with 0 being the most significant
32 (i.e. BITS_BIG_ENDIAN type numbering), and specify which bits each field
33 contains with the *_start and *_len fields. */
34
35 /* What is the order of the bytes? */
36
37 enum floatformat_byteorders {
38 /* Standard little endian byte order.
39 EX: 1.2345678e10 => 00 00 80 c5 e0 fe 06 42 */
40 floatformat_little,
41
42 /* Standard big endian byte order.
43 EX: 1.2345678e10 => 42 06 fe e0 c5 80 00 00 */
44 floatformat_big,
45
46 /* Little endian byte order but big endian word order.
47 EX: 1.2345678e10 => e0 fe 06 42 00 00 80 c5 */
48 floatformat_littlebyte_bigword,
49
50 /* VAX byte order. Little endian byte order with 16-bit words. The
51 following example is an illustration of the byte order only; VAX
52 doesn't have a fully IEEE compliant floating-point format.
53 EX: 1.2345678e10 => 80 c5 00 00 06 42 e0 fe */
54 floatformat_vax
55 };
56
57 enum floatformat_intbit { floatformat_intbit_yes, floatformat_intbit_no };
58
59 struct floatformat
60 {
61 enum floatformat_byteorders byteorder;
62 unsigned int totalsize; /* Total size of number in bits */
63
64 /* Sign bit is always one bit long. 1 means negative, 0 means positive. */
65 unsigned int sign_start;
66
67 unsigned int exp_start;
68 unsigned int exp_len;
69 /* Bias added to a "true" exponent to form the biased exponent. It
70 is intentionally signed as, otherwize, -exp_bias can turn into a
71 very large number (e.g., given the exp_bias of 0x3fff and a 64
72 bit long, the equation (long)(1 - exp_bias) evaluates to
73 4294950914) instead of -16382). */
74 int exp_bias;
75 /* Exponent value which indicates NaN. This is the actual value stored in
76 the float, not adjusted by the exp_bias. This usually consists of all
77 one bits. */
78 unsigned int exp_nan;
79
80 unsigned int man_start;
81 unsigned int man_len;
82
83 /* Is the integer bit explicit or implicit? */
84 enum floatformat_intbit intbit;
85
86 /* Internal name for debugging. */
87 const char *name;
88
89 /* Validator method. */
90 int (*is_valid) (const struct floatformat *fmt, const void *from);
91
92 /* Is the format actually the sum of two smaller floating point
93 formats (IBM long double, as described in
94 libgcc/config/rs6000/ibm-ldouble-format)? If so, this is the
95 smaller format in question, and the fields sign_start through
96 intbit describe the first half. If not, this is NULL. */
97 const struct floatformat *split_half;
98 };
99
100 /* floatformats for IEEE half, single, double and quad, big and little endian. */
101
102 extern const struct floatformat floatformat_ieee_half_big;
103 extern const struct floatformat floatformat_ieee_half_little;
104 extern const struct floatformat floatformat_ieee_single_big;
105 extern const struct floatformat floatformat_ieee_single_little;
106 extern const struct floatformat floatformat_ieee_double_big;
107 extern const struct floatformat floatformat_ieee_double_little;
108 extern const struct floatformat floatformat_ieee_quad_big;
109 extern const struct floatformat floatformat_ieee_quad_little;
110
111 /* floatformat for ARM IEEE double, little endian bytes and big endian words */
112
113 extern const struct floatformat floatformat_ieee_double_littlebyte_bigword;
114
115 /* floatformats for VAX. */
116
117 extern const struct floatformat floatformat_vax_f;
118 extern const struct floatformat floatformat_vax_d;
119 extern const struct floatformat floatformat_vax_g;
120
121 /* floatformats for various extendeds. */
122
123 extern const struct floatformat floatformat_i387_ext;
124 extern const struct floatformat floatformat_m68881_ext;
125 extern const struct floatformat floatformat_i960_ext;
126 extern const struct floatformat floatformat_m88110_ext;
127 extern const struct floatformat floatformat_m88110_harris_ext;
128 extern const struct floatformat floatformat_arm_ext_big;
129 extern const struct floatformat floatformat_arm_ext_littlebyte_bigword;
130 /* IA-64 Floating Point register spilt into memory. */
131 extern const struct floatformat floatformat_ia64_spill_big;
132 extern const struct floatformat floatformat_ia64_spill_little;
133 /* IBM long double (double+double). */
134 extern const struct floatformat floatformat_ibm_long_double_big;
135 extern const struct floatformat floatformat_ibm_long_double_little;
136 /* bfloat16. */
137 extern const struct floatformat floatformat_bfloat16_big;
138 extern const struct floatformat floatformat_bfloat16_little;
139
140 /* Convert from FMT to a double.
141 FROM is the address of the extended float.
142 Store the double in *TO. */
143
144 extern void
145 floatformat_to_double (const struct floatformat *, const void *, double *);
146
147 /* The converse: convert the double *FROM to FMT
148 and store where TO points. */
149
150 extern void
151 floatformat_from_double (const struct floatformat *, const double *, void *);
152
153 /* Return non-zero iff the data at FROM is a valid number in format FMT. */
154
155 extern int
156 floatformat_is_valid (const struct floatformat *fmt, const void *from);
157
158 #ifdef __cplusplus
159 }
160 #endif
161
162 #endif /* defined (FLOATFORMAT_H) */