lib/ieee754.in.h

   1 /* Copyright (C) 1992-2024 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <https://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _IEEE754_H
  19 #define _IEEE754_H 1
  20
  21 #ifndef _GL_GNULIB_HEADER
  22 /* Ordinary glibc usage.  */
  23 # include <features.h>
  24 # include <bits/endian.h>
  25 # define _IEEE754_BYTE_ORDER __BYTE_ORDER
  26 # define _IEEE754_BIG_ENDIAN __BIG_ENDIAN
  27 # define _IEEE754_LITTLE_ENDIAN __LITTLE_ENDIAN
  28 # define _IEEE754_FLOAT_WORD_ORDER __FLOAT_WORD_ORDER
  29 #else
  30 /* Gnulib usage.  */
  31 # include <endian.h>
  32 # define _IEEE754_BYTE_ORDER BYTE_ORDER
  33 # define _IEEE754_BIG_ENDIAN BIG_ENDIAN
  34 # define _IEEE754_LITTLE_ENDIAN LITTLE_ENDIAN
  35 # define _IEEE754_FLOAT_WORD_ORDER BYTE_ORDER
  36 #endif
  37
  38 #ifdef __cplusplus
  39 extern "C" {
  40 #endif
  41
  42 union ieee754_float
  43   {
  44     float f;
  45
  46     /* This is the IEEE 754 single-precision format.  */
  47     struct
  48       {
  49 #if     _IEEE754_BYTE_ORDER == _IEEE754_BIG_ENDIAN
  50         unsigned int negative:1;
  51         unsigned int exponent:8;
  52         unsigned int mantissa:23;
  53 #endif                          /* Big endian.  */
  54 #if     _IEEE754_BYTE_ORDER == _IEEE754_LITTLE_ENDIAN
  55         unsigned int mantissa:23;
  56         unsigned int exponent:8;
  57         unsigned int negative:1;
  58 #endif                          /* Little endian.  */
  59       } ieee;
  60
  61     /* This format makes it easier to see if a NaN is a signalling NaN.  */
  62     struct
  63       {
  64 #if     _IEEE754_BYTE_ORDER == _IEEE754_BIG_ENDIAN
  65         unsigned int negative:1;
  66         unsigned int exponent:8;
  67         unsigned int quiet_nan:1;
  68         unsigned int mantissa:22;
  69 #endif                          /* Big endian.  */
  70 #if     _IEEE754_BYTE_ORDER == _IEEE754_LITTLE_ENDIAN
  71         unsigned int mantissa:22;
  72         unsigned int quiet_nan:1;
  73         unsigned int exponent:8;
  74         unsigned int negative:1;
  75 #endif                          /* Little endian.  */
  76       } ieee_nan;
  77   };
  78
  79 #define IEEE754_FLOAT_BIAS      0x7f /* Added to exponent.  */
  80
  81
  82 union ieee754_double
  83   {
  84     double d;
  85
  86     /* This is the IEEE 754 double-precision format.  */
  87     struct
  88       {
  89 #if     _IEEE754_BYTE_ORDER == _IEEE754_BIG_ENDIAN
  90         unsigned int negative:1;
  91         unsigned int exponent:11;
  92         /* Together these comprise the mantissa.  */
  93         unsigned int mantissa0:20;
  94         unsigned int mantissa1:32;
  95 #endif                          /* Big endian.  */
  96 #if     _IEEE754_BYTE_ORDER == _IEEE754_LITTLE_ENDIAN
  97 # if    _IEEE754_FLOAT_WORD_ORDER == _IEEE754_BIG_ENDIAN
  98         unsigned int mantissa0:20;
  99         unsigned int exponent:11;
 100         unsigned int negative:1;
 101         unsigned int mantissa1:32;
 102 # else
 103         /* Together these comprise the mantissa.  */
 104         unsigned int mantissa1:32;
 105         unsigned int mantissa0:20;
 106         unsigned int exponent:11;
 107         unsigned int negative:1;
 108 # endif
 109 #endif                          /* Little endian.  */
 110       } ieee;
 111
 112     /* This format makes it easier to see if a NaN is a signalling NaN.  */
 113     struct
 114       {
 115 #if     _IEEE754_BYTE_ORDER == _IEEE754_BIG_ENDIAN
 116         unsigned int negative:1;
 117         unsigned int exponent:11;
 118         unsigned int quiet_nan:1;
 119         /* Together these comprise the mantissa.  */
 120         unsigned int mantissa0:19;
 121         unsigned int mantissa1:32;
 122 #else
 123 # if    _IEEE754_FLOAT_WORD_ORDER == _IEEE754_BIG_ENDIAN
 124         unsigned int mantissa0:19;
 125         unsigned int quiet_nan:1;
 126         unsigned int exponent:11;
 127         unsigned int negative:1;
 128         unsigned int mantissa1:32;
 129 # else
 130         /* Together these comprise the mantissa.  */
 131         unsigned int mantissa1:32;
 132         unsigned int mantissa0:19;
 133         unsigned int quiet_nan:1;
 134         unsigned int exponent:11;
 135         unsigned int negative:1;
 136 # endif
 137 #endif
 138       } ieee_nan;
 139   };
 140
 141 #define IEEE754_DOUBLE_BIAS     0x3ff /* Added to exponent.  */
 142
 143
 144 union ieee854_long_double
 145   {
 146     long double d;
 147
 148     /* This is the IEEE 854 double-extended-precision format.  */
 149     struct
 150       {
 151 #if     _IEEE754_BYTE_ORDER == _IEEE754_BIG_ENDIAN
 152         unsigned int negative:1;
 153         unsigned int exponent:15;
 154         unsigned int empty:16;
 155         unsigned int mantissa0:32;
 156         unsigned int mantissa1:32;
 157 #endif
 158 #if     _IEEE754_BYTE_ORDER == _IEEE754_LITTLE_ENDIAN
 159 # if    _IEEE754_FLOAT_WORD_ORDER == _IEEE754_BIG_ENDIAN
 160         unsigned int exponent:15;
 161         unsigned int negative:1;
 162         unsigned int empty:16;
 163         unsigned int mantissa0:32;
 164         unsigned int mantissa1:32;
 165 # else
 166         unsigned int mantissa1:32;
 167         unsigned int mantissa0:32;
 168         unsigned int exponent:15;
 169         unsigned int negative:1;
 170         unsigned int empty:16;
 171 # endif
 172 #endif
 173       } ieee;
 174
 175     /* This is for NaNs in the IEEE 854 double-extended-precision format.  */
 176     struct
 177       {
 178 #if     _IEEE754_BYTE_ORDER == _IEEE754_BIG_ENDIAN
 179         unsigned int negative:1;
 180         unsigned int exponent:15;
 181         unsigned int empty:16;
 182         unsigned int one:1;
 183         unsigned int quiet_nan:1;
 184         unsigned int mantissa0:30;
 185         unsigned int mantissa1:32;
 186 #endif
 187 #if     _IEEE754_BYTE_ORDER == _IEEE754_LITTLE_ENDIAN
 188 # if    _IEEE754_FLOAT_WORD_ORDER == _IEEE754_BIG_ENDIAN
 189         unsigned int exponent:15;
 190         unsigned int negative:1;
 191         unsigned int empty:16;
 192         unsigned int mantissa0:30;
 193         unsigned int quiet_nan:1;
 194         unsigned int one:1;
 195         unsigned int mantissa1:32;
 196 # else
 197         unsigned int mantissa1:32;
 198         unsigned int mantissa0:30;
 199         unsigned int quiet_nan:1;
 200         unsigned int one:1;
 201         unsigned int exponent:15;
 202         unsigned int negative:1;
 203         unsigned int empty:16;
 204 # endif
 205 #endif
 206       } ieee_nan;
 207   };
 208
 209 #define IEEE854_LONG_DOUBLE_BIAS 0x3fff
 210
 211 #ifdef __cplusplus
 212 }
 213 #endif
 214
 215 #endif /* ieee754.h */