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0
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1 /* IEEE floating point support routines, for GDB, the GNU Debugger.
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2 Copyright 1991, 1994, 1999, 2000, 2003, 2005, 2006
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3 Free Software Foundation, Inc.
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4
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5 This file is part of GDB.
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6
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7 This program is free software; you can redistribute it and/or modify
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8 it under the terms of the GNU General Public License as published by
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9 the Free Software Foundation; either version 2 of the License, or
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10 (at your option) any later version.
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11
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12 This program is distributed in the hope that it will be useful,
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13 but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 GNU General Public License for more details.
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16
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17 You should have received a copy of the GNU General Public License
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18 along with this program; if not, write to the Free Software
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19 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */
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20
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21 /* This is needed to pick up the NAN macro on some systems. */
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22 #define _GNU_SOURCE
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23
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24 #ifdef HAVE_CONFIG_H
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25 #include "config.h"
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26 #endif
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27
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28 #include <math.h>
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29
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30 #ifdef HAVE_STRING_H
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31 #include <string.h>
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32 #endif
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33
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34 /* On some platforms, <float.h> provides DBL_QNAN. */
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35 #ifdef STDC_HEADERS
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36 #include <float.h>
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37 #endif
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38
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39 #include "ansidecl.h"
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40 #include "libiberty.h"
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41 #include "floatformat.h"
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42
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43 #ifndef INFINITY
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44 #ifdef HUGE_VAL
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45 #define INFINITY HUGE_VAL
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46 #else
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47 #define INFINITY (1.0 / 0.0)
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48 #endif
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49 #endif
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50
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51 #ifndef NAN
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52 #ifdef DBL_QNAN
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53 #define NAN DBL_QNAN
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54 #else
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55 #define NAN (0.0 / 0.0)
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56 #endif
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57 #endif
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58
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59 static int mant_bits_set (const struct floatformat *, const unsigned char *);
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60 static unsigned long get_field (const unsigned char *,
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61 enum floatformat_byteorders,
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62 unsigned int,
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63 unsigned int,
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64 unsigned int);
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65 static int floatformat_always_valid (const struct floatformat *fmt,
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66 const void *from);
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67
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68 static int
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69 floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED,
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70 const void *from ATTRIBUTE_UNUSED)
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71 {
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72 return 1;
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73 }
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74
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75 /* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not
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76 going to bother with trying to muck around with whether it is defined in
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77 a system header, what we do if not, etc. */
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78 #define FLOATFORMAT_CHAR_BIT 8
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79
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80 /* floatformats for IEEE single and double, big and little endian. */
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81 const struct floatformat floatformat_ieee_single_big =
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82 {
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83 floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23,
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84 floatformat_intbit_no,
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85 "floatformat_ieee_single_big",
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86 floatformat_always_valid,
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87 NULL
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88 };
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89 const struct floatformat floatformat_ieee_single_little =
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90 {
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91 floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23,
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92 floatformat_intbit_no,
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93 "floatformat_ieee_single_little",
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94 floatformat_always_valid,
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95 NULL
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96 };
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97 const struct floatformat floatformat_ieee_double_big =
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98 {
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99 floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52,
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100 floatformat_intbit_no,
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101 "floatformat_ieee_double_big",
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102 floatformat_always_valid,
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103 NULL
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104 };
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105 const struct floatformat floatformat_ieee_double_little =
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106 {
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107 floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52,
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108 floatformat_intbit_no,
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109 "floatformat_ieee_double_little",
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110 floatformat_always_valid,
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111 NULL
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112 };
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113
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114 /* floatformat for IEEE double, little endian byte order, with big endian word
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115 ordering, as on the ARM. */
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116
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117 const struct floatformat floatformat_ieee_double_littlebyte_bigword =
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118 {
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119 floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52,
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120 floatformat_intbit_no,
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121 "floatformat_ieee_double_littlebyte_bigword",
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122 floatformat_always_valid,
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123 NULL
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124 };
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125
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126 /* floatformat for VAX. Not quite IEEE, but close enough. */
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127
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128 const struct floatformat floatformat_vax_f =
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129 {
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130 floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23,
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131 floatformat_intbit_no,
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132 "floatformat_vax_f",
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133 floatformat_always_valid,
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134 NULL
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135 };
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136 const struct floatformat floatformat_vax_d =
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137 {
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138 floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55,
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139 floatformat_intbit_no,
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140 "floatformat_vax_d",
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141 floatformat_always_valid,
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142 NULL
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143 };
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144 const struct floatformat floatformat_vax_g =
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145 {
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146 floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52,
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147 floatformat_intbit_no,
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148 "floatformat_vax_g",
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149 floatformat_always_valid,
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150 NULL
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151 };
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152
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153 static int floatformat_i387_ext_is_valid (const struct floatformat *fmt,
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154 const void *from);
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155
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156 static int
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157 floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from)
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158 {
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159 /* In the i387 double-extended format, if the exponent is all ones,
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160 then the integer bit must be set. If the exponent is neither 0
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161 nor ~0, the intbit must also be set. Only if the exponent is
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162 zero can it be zero, and then it must be zero. */
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163 unsigned long exponent, int_bit;
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164 const unsigned char *ufrom = (const unsigned char *) from;
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165
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166 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
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167 fmt->exp_start, fmt->exp_len);
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168 int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize,
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169 fmt->man_start, 1);
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170
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171 if ((exponent == 0) != (int_bit == 0))
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172 return 0;
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173 else
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174 return 1;
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175 }
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176
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177 const struct floatformat floatformat_i387_ext =
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178 {
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179 floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
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180 floatformat_intbit_yes,
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181 "floatformat_i387_ext",
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182 floatformat_i387_ext_is_valid,
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183 NULL
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184 };
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185 const struct floatformat floatformat_m68881_ext =
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186 {
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187 /* Note that the bits from 16 to 31 are unused. */
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188 floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64,
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189 floatformat_intbit_yes,
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190 "floatformat_m68881_ext",
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191 floatformat_always_valid,
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192 NULL
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193 };
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194 const struct floatformat floatformat_i960_ext =
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195 {
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196 /* Note that the bits from 0 to 15 are unused. */
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197 floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64,
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198 floatformat_intbit_yes,
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199 "floatformat_i960_ext",
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200 floatformat_always_valid,
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201 NULL
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202 };
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203 const struct floatformat floatformat_m88110_ext =
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204 {
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205 floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64,
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206 floatformat_intbit_yes,
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207 "floatformat_m88110_ext",
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208 floatformat_always_valid,
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209 NULL
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210 };
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211 const struct floatformat floatformat_m88110_harris_ext =
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212 {
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213 /* Harris uses raw format 128 bytes long, but the number is just an ieee
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214 double, and the last 64 bits are wasted. */
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215 floatformat_big,128, 0, 1, 11, 0x3ff, 0x7ff, 12, 52,
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216 floatformat_intbit_no,
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217 "floatformat_m88110_ext_harris",
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218 floatformat_always_valid,
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219 NULL
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220 };
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221 const struct floatformat floatformat_arm_ext_big =
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222 {
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223 /* Bits 1 to 16 are unused. */
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224 floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
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225 floatformat_intbit_yes,
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226 "floatformat_arm_ext_big",
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227 floatformat_always_valid,
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228 NULL
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229 };
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230 const struct floatformat floatformat_arm_ext_littlebyte_bigword =
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231 {
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232 /* Bits 1 to 16 are unused. */
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233 floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64,
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234 floatformat_intbit_yes,
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235 "floatformat_arm_ext_littlebyte_bigword",
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236 floatformat_always_valid,
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237 NULL
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238 };
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239 const struct floatformat floatformat_ia64_spill_big =
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240 {
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241 floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
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242 floatformat_intbit_yes,
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243 "floatformat_ia64_spill_big",
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244 floatformat_always_valid,
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245 NULL
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246 };
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247 const struct floatformat floatformat_ia64_spill_little =
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248 {
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249 floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64,
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250 floatformat_intbit_yes,
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251 "floatformat_ia64_spill_little",
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252 floatformat_always_valid,
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253 NULL
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254 };
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255 const struct floatformat floatformat_ia64_quad_big =
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256 {
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257 floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
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258 floatformat_intbit_no,
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259 "floatformat_ia64_quad_big",
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260 floatformat_always_valid,
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261 NULL
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262 };
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263 const struct floatformat floatformat_ia64_quad_little =
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264 {
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265 floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112,
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266 floatformat_intbit_no,
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267 "floatformat_ia64_quad_little",
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268 floatformat_always_valid,
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269 NULL
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270 };
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271
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272 static int
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273 floatformat_ibm_long_double_is_valid (const struct floatformat *fmt,
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274 const void *from)
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275 {
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276 const unsigned char *ufrom = (const unsigned char *) from;
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277 const struct floatformat *hfmt = fmt->split_half;
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278 long top_exp, bot_exp;
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279 int top_nan = 0;
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280
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281 top_exp = get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
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282 hfmt->exp_start, hfmt->exp_len);
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283 bot_exp = get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize,
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284 hfmt->exp_start, hfmt->exp_len);
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285
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286 if ((unsigned long) top_exp == hfmt->exp_nan)
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287 top_nan = mant_bits_set (hfmt, ufrom);
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288
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289 /* A NaN is valid with any low part. */
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290 if (top_nan)
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291 return 1;
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292
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293 /* An infinity, zero or denormal requires low part 0 (positive or
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294 negative). */
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295 if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0)
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296 {
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297 if (bot_exp != 0)
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298 return 0;
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299
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300 return !mant_bits_set (hfmt, ufrom + 8);
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301 }
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302
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303 /* The top part is now a finite normal value. The long double value
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304 is the sum of the two parts, and the top part must equal the
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305 result of rounding the long double value to nearest double. Thus
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306 the bottom part must be <= 0.5ulp of the top part in absolute
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307 value, and if it is < 0.5ulp then the long double is definitely
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308 valid. */
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309 if (bot_exp < top_exp - 53)
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310 return 1;
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311 if (bot_exp > top_exp - 53 && bot_exp != 0)
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312 return 0;
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313 if (bot_exp == 0)
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314 {
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315 /* The bottom part is 0 or denormal. Determine which, and if
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316 denormal the first two set bits. */
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317 int first_bit = -1, second_bit = -1, cur_bit;
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318 for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++)
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319 if (get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize,
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320 hfmt->man_start + cur_bit, 1))
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321 {
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322 if (first_bit == -1)
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323 first_bit = cur_bit;
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324 else
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325 {
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326 second_bit = cur_bit;
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327 break;
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328 }
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329 }
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330 /* Bottom part 0 is OK. */
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331 if (first_bit == -1)
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332 return 1;
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333 /* The real exponent of the bottom part is -first_bit. */
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334 if (-first_bit < top_exp - 53)
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335 return 1;
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336 if (-first_bit > top_exp - 53)
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337 return 0;
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338 /* The bottom part is at least 0.5ulp of the top part. For this
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339 to be OK, the bottom part must be exactly 0.5ulp (i.e. no
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340 more bits set) and the top part must have last bit 0. */
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341 if (second_bit != -1)
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342 return 0;
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343 return !get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
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344 hfmt->man_start + hfmt->man_len - 1, 1);
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345 }
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346 else
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347 {
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348 /* The bottom part is at least 0.5ulp of the top part. For this
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349 to be OK, it must be exactly 0.5ulp (i.e. no explicit bits
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350 set) and the top part must have last bit 0. */
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351 if (get_field (ufrom, hfmt->byteorder, hfmt->totalsize,
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352 hfmt->man_start + hfmt->man_len - 1, 1))
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353 return 0;
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354 return !mant_bits_set (hfmt, ufrom + 8);
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355 }
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356 }
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357
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358 const struct floatformat floatformat_ibm_long_double =
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359 {
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360 floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52,
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361 floatformat_intbit_no,
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362 "floatformat_ibm_long_double",
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363 floatformat_ibm_long_double_is_valid,
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364 &floatformat_ieee_double_big
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365 };
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366
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367
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368 #ifndef min
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369 #define min(a, b) ((a) < (b) ? (a) : (b))
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370 #endif
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371
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372 /* Return 1 if any bits are explicitly set in the mantissa of UFROM,
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373 format FMT, 0 otherwise. */
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374 static int
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375 mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom)
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376 {
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377 unsigned int mant_bits, mant_off;
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378 int mant_bits_left;
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379
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380 mant_off = fmt->man_start;
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381 mant_bits_left = fmt->man_len;
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382 while (mant_bits_left > 0)
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383 {
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384 mant_bits = min (mant_bits_left, 32);
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385
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386 if (get_field (ufrom, fmt->byteorder, fmt->totalsize,
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387 mant_off, mant_bits) != 0)
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388 return 1;
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389
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390 mant_off += mant_bits;
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391 mant_bits_left -= mant_bits;
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392 }
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393 return 0;
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394 }
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395
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396 /* Extract a field which starts at START and is LEN bits long. DATA and
|
|
|
397 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
|
|
|
398 static unsigned long
|
|
|
399 get_field (const unsigned char *data, enum floatformat_byteorders order,
|
|
|
400 unsigned int total_len, unsigned int start, unsigned int len)
|
|
|
401 {
|
|
|
402 unsigned long result = 0;
|
|
|
403 unsigned int cur_byte;
|
|
|
404 int lo_bit, hi_bit, cur_bitshift = 0;
|
|
|
405 int nextbyte = (order == floatformat_little) ? 1 : -1;
|
|
|
406
|
|
|
407 /* Start is in big-endian bit order! Fix that first. */
|
|
|
408 start = total_len - (start + len);
|
|
|
409
|
|
|
410 /* Start at the least significant part of the field. */
|
|
|
411 if (order == floatformat_little)
|
|
|
412 cur_byte = start / FLOATFORMAT_CHAR_BIT;
|
|
|
413 else
|
|
|
414 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
|
|
|
415
|
|
|
416 lo_bit = start % FLOATFORMAT_CHAR_BIT;
|
|
|
417 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
|
|
|
418
|
|
|
419 do
|
|
|
420 {
|
|
|
421 unsigned int shifted = *(data + cur_byte) >> lo_bit;
|
|
|
422 unsigned int bits = hi_bit - lo_bit;
|
|
|
423 unsigned int mask = (1 << bits) - 1;
|
|
|
424 result |= (shifted & mask) << cur_bitshift;
|
|
|
425 len -= bits;
|
|
|
426 cur_bitshift += bits;
|
|
|
427 cur_byte += nextbyte;
|
|
|
428 lo_bit = 0;
|
|
|
429 hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
|
|
|
430 }
|
|
|
431 while (len != 0);
|
|
|
432
|
|
|
433 return result;
|
|
|
434 }
|
|
|
435
|
|
|
436 /* Convert from FMT to a double.
|
|
|
437 FROM is the address of the extended float.
|
|
|
438 Store the double in *TO. */
|
|
|
439
|
|
|
440 void
|
|
|
441 floatformat_to_double (const struct floatformat *fmt,
|
|
|
442 const void *from, double *to)
|
|
|
443 {
|
|
|
444 const unsigned char *ufrom = (const unsigned char *) from;
|
|
|
445 double dto;
|
|
|
446 long exponent;
|
|
|
447 unsigned long mant;
|
|
|
448 unsigned int mant_bits, mant_off;
|
|
|
449 int mant_bits_left;
|
|
|
450 int special_exponent; /* It's a NaN, denorm or zero */
|
|
|
451
|
|
|
452 /* Split values are not handled specially, since the top half has
|
|
|
453 the correctly rounded double value (in the only supported case of
|
|
|
454 split values). */
|
|
|
455
|
|
|
456 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize,
|
|
|
457 fmt->exp_start, fmt->exp_len);
|
|
|
458
|
|
|
459 /* If the exponent indicates a NaN, we don't have information to
|
|
|
460 decide what to do. So we handle it like IEEE, except that we
|
|
|
461 don't try to preserve the type of NaN. FIXME. */
|
|
|
462 if ((unsigned long) exponent == fmt->exp_nan)
|
|
|
463 {
|
|
|
464 int nan = mant_bits_set (fmt, ufrom);
|
|
|
465
|
|
|
466 /* On certain systems (such as GNU/Linux), the use of the
|
|
|
467 INFINITY macro below may generate a warning that can not be
|
|
|
468 silenced due to a bug in GCC (PR preprocessor/11931). The
|
|
|
469 preprocessor fails to recognise the __extension__ keyword in
|
|
|
470 conjunction with the GNU/C99 extension for hexadecimal
|
|
|
471 floating point constants and will issue a warning when
|
|
|
472 compiling with -pedantic. */
|
|
|
473 if (nan)
|
|
|
474 dto = NAN;
|
|
|
475 else
|
|
|
476 dto = INFINITY;
|
|
|
477
|
|
|
478 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
|
|
|
479 dto = -dto;
|
|
|
480
|
|
|
481 *to = dto;
|
|
|
482
|
|
|
483 return;
|
|
|
484 }
|
|
|
485
|
|
|
486 mant_bits_left = fmt->man_len;
|
|
|
487 mant_off = fmt->man_start;
|
|
|
488 dto = 0.0;
|
|
|
489
|
|
|
490 special_exponent = exponent == 0 || (unsigned long) exponent == fmt->exp_nan;
|
|
|
491
|
|
|
492 /* Don't bias zero's, denorms or NaNs. */
|
|
|
493 if (!special_exponent)
|
|
|
494 exponent -= fmt->exp_bias;
|
|
|
495
|
|
|
496 /* Build the result algebraically. Might go infinite, underflow, etc;
|
|
|
497 who cares. */
|
|
|
498
|
|
|
499 /* If this format uses a hidden bit, explicitly add it in now. Otherwise,
|
|
|
500 increment the exponent by one to account for the integer bit. */
|
|
|
501
|
|
|
502 if (!special_exponent)
|
|
|
503 {
|
|
|
504 if (fmt->intbit == floatformat_intbit_no)
|
|
|
505 dto = ldexp (1.0, exponent);
|
|
|
506 else
|
|
|
507 exponent++;
|
|
|
508 }
|
|
|
509
|
|
|
510 while (mant_bits_left > 0)
|
|
|
511 {
|
|
|
512 mant_bits = min (mant_bits_left, 32);
|
|
|
513
|
|
|
514 mant = get_field (ufrom, fmt->byteorder, fmt->totalsize,
|
|
|
515 mant_off, mant_bits);
|
|
|
516
|
|
|
517 /* Handle denormalized numbers. FIXME: What should we do for
|
|
|
518 non-IEEE formats? */
|
|
|
519 if (special_exponent && exponent == 0 && mant != 0)
|
|
|
520 dto += ldexp ((double)mant,
|
|
|
521 (- fmt->exp_bias
|
|
|
522 - mant_bits
|
|
|
523 - (mant_off - fmt->man_start)
|
|
|
524 + 1));
|
|
|
525 else
|
|
|
526 dto += ldexp ((double)mant, exponent - mant_bits);
|
|
|
527 if (exponent != 0)
|
|
|
528 exponent -= mant_bits;
|
|
|
529 mant_off += mant_bits;
|
|
|
530 mant_bits_left -= mant_bits;
|
|
|
531 }
|
|
|
532
|
|
|
533 /* Negate it if negative. */
|
|
|
534 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1))
|
|
|
535 dto = -dto;
|
|
|
536 *to = dto;
|
|
|
537 }
|
|
|
538
|
|
|
539 static void put_field (unsigned char *, enum floatformat_byteorders,
|
|
|
540 unsigned int,
|
|
|
541 unsigned int,
|
|
|
542 unsigned int,
|
|
|
543 unsigned long);
|
|
|
544
|
|
|
545 /* Set a field which starts at START and is LEN bits long. DATA and
|
|
|
546 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */
|
|
|
547 static void
|
|
|
548 put_field (unsigned char *data, enum floatformat_byteorders order,
|
|
|
549 unsigned int total_len, unsigned int start, unsigned int len,
|
|
|
550 unsigned long stuff_to_put)
|
|
|
551 {
|
|
|
552 unsigned int cur_byte;
|
|
|
553 int lo_bit, hi_bit;
|
|
|
554 int nextbyte = (order == floatformat_little) ? 1 : -1;
|
|
|
555
|
|
|
556 /* Start is in big-endian bit order! Fix that first. */
|
|
|
557 start = total_len - (start + len);
|
|
|
558
|
|
|
559 /* Start at the least significant part of the field. */
|
|
|
560 if (order == floatformat_little)
|
|
|
561 cur_byte = start / FLOATFORMAT_CHAR_BIT;
|
|
|
562 else
|
|
|
563 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT;
|
|
|
564
|
|
|
565 lo_bit = start % FLOATFORMAT_CHAR_BIT;
|
|
|
566 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT);
|
|
|
567
|
|
|
568 do
|
|
|
569 {
|
|
|
570 unsigned char *byte_ptr = data + cur_byte;
|
|
|
571 unsigned int bits = hi_bit - lo_bit;
|
|
|
572 unsigned int mask = ((1 << bits) - 1) << lo_bit;
|
|
|
573 *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask);
|
|
|
574 stuff_to_put >>= bits;
|
|
|
575 len -= bits;
|
|
|
576 cur_byte += nextbyte;
|
|
|
577 lo_bit = 0;
|
|
|
578 hi_bit = min (len, FLOATFORMAT_CHAR_BIT);
|
|
|
579 }
|
|
|
580 while (len != 0);
|
|
|
581 }
|
|
|
582
|
|
|
583 /* The converse: convert the double *FROM to an extended float
|
|
|
584 and store where TO points. Neither FROM nor TO have any alignment
|
|
|
585 restrictions. */
|
|
|
586
|
|
|
587 void
|
|
|
588 floatformat_from_double (const struct floatformat *fmt,
|
|
|
589 const double *from, void *to)
|
|
|
590 {
|
|
|
591 double dfrom;
|
|
|
592 int exponent;
|
|
|
593 double mant;
|
|
|
594 unsigned int mant_bits, mant_off;
|
|
|
595 int mant_bits_left;
|
|
|
596 unsigned char *uto = (unsigned char *) to;
|
|
|
597
|
|
|
598 dfrom = *from;
|
|
|
599 memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT);
|
|
|
600
|
|
|
601 /* Split values are not handled specially, since a bottom half of
|
|
|
602 zero is correct for any value representable as double (in the
|
|
|
603 only supported case of split values). */
|
|
|
604
|
|
|
605 /* If negative, set the sign bit. */
|
|
|
606 if (dfrom < 0)
|
|
|
607 {
|
|
|
608 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1);
|
|
|
609 dfrom = -dfrom;
|
|
|
610 }
|
|
|
611
|
|
|
612 if (dfrom == 0)
|
|
|
613 {
|
|
|
614 /* 0.0. */
|
|
|
615 return;
|
|
|
616 }
|
|
|
617
|
|
|
618 if (dfrom != dfrom)
|
|
|
619 {
|
|
|
620 /* NaN. */
|
|
|
621 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
|
|
|
622 fmt->exp_len, fmt->exp_nan);
|
|
|
623 /* Be sure it's not infinity, but NaN value is irrelevant. */
|
|
|
624 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start,
|
|
|
625 32, 1);
|
|
|
626 return;
|
|
|
627 }
|
|
|
628
|
|
|
629 if (dfrom + dfrom == dfrom)
|
|
|
630 {
|
|
|
631 /* This can only happen for an infinite value (or zero, which we
|
|
|
632 already handled above). */
|
|
|
633 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
|
|
|
634 fmt->exp_len, fmt->exp_nan);
|
|
|
635 return;
|
|
|
636 }
|
|
|
637
|
|
|
638 mant = frexp (dfrom, &exponent);
|
|
|
639 if (exponent + fmt->exp_bias - 1 > 0)
|
|
|
640 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
|
|
|
641 fmt->exp_len, exponent + fmt->exp_bias - 1);
|
|
|
642 else
|
|
|
643 {
|
|
|
644 /* Handle a denormalized number. FIXME: What should we do for
|
|
|
645 non-IEEE formats? */
|
|
|
646 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start,
|
|
|
647 fmt->exp_len, 0);
|
|
|
648 mant = ldexp (mant, exponent + fmt->exp_bias - 1);
|
|
|
649 }
|
|
|
650
|
|
|
651 mant_bits_left = fmt->man_len;
|
|
|
652 mant_off = fmt->man_start;
|
|
|
653 while (mant_bits_left > 0)
|
|
|
654 {
|
|
|
655 unsigned long mant_long;
|
|
|
656 mant_bits = mant_bits_left < 32 ? mant_bits_left : 32;
|
|
|
657
|
|
|
658 mant *= 4294967296.0;
|
|
|
659 mant_long = (unsigned long)mant;
|
|
|
660 mant -= mant_long;
|
|
|
661
|
|
|
662 /* If the integer bit is implicit, and we are not creating a
|
|
|
663 denormalized number, then we need to discard it. */
|
|
|
664 if ((unsigned int) mant_bits_left == fmt->man_len
|
|
|
665 && fmt->intbit == floatformat_intbit_no
|
|
|
666 && exponent + fmt->exp_bias - 1 > 0)
|
|
|
667 {
|
|
|
668 mant_long &= 0x7fffffff;
|
|
|
669 mant_bits -= 1;
|
|
|
670 }
|
|
|
671 else if (mant_bits < 32)
|
|
|
672 {
|
|
|
673 /* The bits we want are in the most significant MANT_BITS bits of
|
|
|
674 mant_long. Move them to the least significant. */
|
|
|
675 mant_long >>= 32 - mant_bits;
|
|
|
676 }
|
|
|
677
|
|
|
678 put_field (uto, fmt->byteorder, fmt->totalsize,
|
|
|
679 mant_off, mant_bits, mant_long);
|
|
|
680 mant_off += mant_bits;
|
|
|
681 mant_bits_left -= mant_bits;
|
|
|
682 }
|
|
|
683 }
|
|
|
684
|
|
|
685 /* Return non-zero iff the data at FROM is a valid number in format FMT. */
|
|
|
686
|
|
|
687 int
|
|
|
688 floatformat_is_valid (const struct floatformat *fmt, const void *from)
|
|
|
689 {
|
|
|
690 return fmt->is_valid (fmt, from);
|
|
|
691 }
|
|
|
692
|
|
|
693
|
|
|
694 #ifdef IEEE_DEBUG
|
|
|
695
|
|
|
696 #include <stdio.h>
|
|
|
697
|
|
|
698 /* This is to be run on a host which uses IEEE floating point. */
|
|
|
699
|
|
|
700 void
|
|
|
701 ieee_test (double n)
|
|
|
702 {
|
|
|
703 double result;
|
|
|
704
|
|
|
705 floatformat_to_double (&floatformat_ieee_double_little, &n, &result);
|
|
|
706 if ((n != result && (! isnan (n) || ! isnan (result)))
|
|
|
707 || (n < 0 && result >= 0)
|
|
|
708 || (n >= 0 && result < 0))
|
|
|
709 printf ("Differ(to): %.20g -> %.20g\n", n, result);
|
|
|
710
|
|
|
711 floatformat_from_double (&floatformat_ieee_double_little, &n, &result);
|
|
|
712 if ((n != result && (! isnan (n) || ! isnan (result)))
|
|
|
713 || (n < 0 && result >= 0)
|
|
|
714 || (n >= 0 && result < 0))
|
|
|
715 printf ("Differ(from): %.20g -> %.20g\n", n, result);
|
|
|
716
|
|
|
717 #if 0
|
|
|
718 {
|
|
|
719 char exten[16];
|
|
|
720
|
|
|
721 floatformat_from_double (&floatformat_m68881_ext, &n, exten);
|
|
|
722 floatformat_to_double (&floatformat_m68881_ext, exten, &result);
|
|
|
723 if (n != result)
|
|
|
724 printf ("Differ(to+from): %.20g -> %.20g\n", n, result);
|
|
|
725 }
|
|
|
726 #endif
|
|
|
727
|
|
|
728 #if IEEE_DEBUG > 1
|
|
|
729 /* This is to be run on a host which uses 68881 format. */
|
|
|
730 {
|
|
|
731 long double ex = *(long double *)exten;
|
|
|
732 if (ex != n)
|
|
|
733 printf ("Differ(from vs. extended): %.20g\n", n);
|
|
|
734 }
|
|
|
735 #endif
|
|
|
736 }
|
|
|
737
|
|
|
738 int
|
|
|
739 main (void)
|
|
|
740 {
|
|
|
741 ieee_test (0.0);
|
|
|
742 ieee_test (0.5);
|
|
|
743 ieee_test (256.0);
|
|
|
744 ieee_test (0.12345);
|
|
|
745 ieee_test (234235.78907234);
|
|
|
746 ieee_test (-512.0);
|
|
|
747 ieee_test (-0.004321);
|
|
|
748 ieee_test (1.2E-70);
|
|
|
749 ieee_test (1.2E-316);
|
|
|
750 ieee_test (4.9406564584124654E-324);
|
|
|
751 ieee_test (- 4.9406564584124654E-324);
|
|
|
752 ieee_test (- 0.0);
|
|
|
753 ieee_test (- INFINITY);
|
|
|
754 ieee_test (- NAN);
|
|
|
755 ieee_test (INFINITY);
|
|
|
756 ieee_test (NAN);
|
|
|
757 return 0;
|
|
|
758 }
|
|
|
759 #endif
|
