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Rev | Author | Line No. | Line |
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5191 | serge | 1 | /* IEEE floating point support routines, for GDB, the GNU Debugger. |
6324 | serge | 2 | Copyright 1991, 1994, 1999, 2000, 2003, 2005, 2006, 2010, 2012, 2015 |
5191 | serge | 3 | Free Software Foundation, Inc. |
4 | |||
5 | This file is part of GDB. |
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6 | |||
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 | |||
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 | |||
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 | |||
21 | /* This is needed to pick up the NAN macro on some systems. */ |
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6324 | serge | 22 | #ifndef _GNU_SOURCE |
5191 | serge | 23 | #define _GNU_SOURCE |
6324 | serge | 24 | #endif |
5191 | serge | 25 | |
26 | #ifdef HAVE_CONFIG_H |
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27 | #include "config.h" |
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28 | #endif |
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29 | |||
30 | #include |
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31 | |||
32 | #ifdef HAVE_STRING_H |
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33 | #include |
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34 | #endif |
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35 | |||
36 | /* On some platforms, |
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37 | #ifdef STDC_HEADERS |
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38 | #include |
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39 | #endif |
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40 | |||
41 | #include "ansidecl.h" |
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42 | #include "libiberty.h" |
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43 | #include "floatformat.h" |
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44 | |||
45 | #ifndef INFINITY |
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46 | #ifdef HUGE_VAL |
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47 | #define INFINITY HUGE_VAL |
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48 | #else |
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49 | #define INFINITY (1.0 / 0.0) |
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50 | #endif |
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51 | #endif |
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52 | |||
53 | #ifndef NAN |
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54 | #ifdef DBL_QNAN |
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55 | #define NAN DBL_QNAN |
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56 | #else |
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57 | #define NAN (0.0 / 0.0) |
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58 | #endif |
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59 | #endif |
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60 | |||
61 | static int mant_bits_set (const struct floatformat *, const unsigned char *); |
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62 | static unsigned long get_field (const unsigned char *, |
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63 | enum floatformat_byteorders, |
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64 | unsigned int, |
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65 | unsigned int, |
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66 | unsigned int); |
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67 | static int floatformat_always_valid (const struct floatformat *fmt, |
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68 | const void *from); |
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69 | |||
70 | static int |
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71 | floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED, |
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72 | const void *from ATTRIBUTE_UNUSED) |
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73 | { |
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74 | return 1; |
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75 | } |
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76 | |||
77 | /* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not |
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78 | going to bother with trying to muck around with whether it is defined in |
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79 | a system header, what we do if not, etc. */ |
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80 | #define FLOATFORMAT_CHAR_BIT 8 |
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81 | |||
82 | /* floatformats for IEEE half, single and double, big and little endian. */ |
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83 | const struct floatformat floatformat_ieee_half_big = |
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84 | { |
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85 | floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10, |
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86 | floatformat_intbit_no, |
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87 | "floatformat_ieee_half_big", |
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88 | floatformat_always_valid, |
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89 | NULL |
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90 | }; |
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91 | const struct floatformat floatformat_ieee_half_little = |
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92 | { |
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93 | floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10, |
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94 | floatformat_intbit_no, |
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95 | "floatformat_ieee_half_little", |
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96 | floatformat_always_valid, |
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97 | NULL |
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98 | }; |
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99 | const struct floatformat floatformat_ieee_single_big = |
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100 | { |
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101 | floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23, |
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102 | floatformat_intbit_no, |
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103 | "floatformat_ieee_single_big", |
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104 | floatformat_always_valid, |
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105 | NULL |
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106 | }; |
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107 | const struct floatformat floatformat_ieee_single_little = |
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108 | { |
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109 | floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23, |
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110 | floatformat_intbit_no, |
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111 | "floatformat_ieee_single_little", |
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112 | floatformat_always_valid, |
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113 | NULL |
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114 | }; |
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115 | const struct floatformat floatformat_ieee_double_big = |
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116 | { |
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117 | floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52, |
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118 | floatformat_intbit_no, |
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119 | "floatformat_ieee_double_big", |
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120 | floatformat_always_valid, |
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121 | NULL |
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122 | }; |
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123 | const struct floatformat floatformat_ieee_double_little = |
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124 | { |
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125 | floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52, |
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126 | floatformat_intbit_no, |
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127 | "floatformat_ieee_double_little", |
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128 | floatformat_always_valid, |
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129 | NULL |
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130 | }; |
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131 | |||
132 | /* floatformat for IEEE double, little endian byte order, with big endian word |
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133 | ordering, as on the ARM. */ |
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134 | |||
135 | const struct floatformat floatformat_ieee_double_littlebyte_bigword = |
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136 | { |
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137 | floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52, |
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138 | floatformat_intbit_no, |
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139 | "floatformat_ieee_double_littlebyte_bigword", |
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140 | floatformat_always_valid, |
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141 | NULL |
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142 | }; |
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143 | |||
144 | /* floatformat for VAX. Not quite IEEE, but close enough. */ |
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145 | |||
146 | const struct floatformat floatformat_vax_f = |
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147 | { |
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148 | floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23, |
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149 | floatformat_intbit_no, |
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150 | "floatformat_vax_f", |
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151 | floatformat_always_valid, |
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152 | NULL |
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153 | }; |
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154 | const struct floatformat floatformat_vax_d = |
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155 | { |
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156 | floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55, |
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157 | floatformat_intbit_no, |
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158 | "floatformat_vax_d", |
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159 | floatformat_always_valid, |
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160 | NULL |
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161 | }; |
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162 | const struct floatformat floatformat_vax_g = |
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163 | { |
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164 | floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52, |
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165 | floatformat_intbit_no, |
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166 | "floatformat_vax_g", |
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167 | floatformat_always_valid, |
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168 | NULL |
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169 | }; |
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170 | |||
171 | static int floatformat_i387_ext_is_valid (const struct floatformat *fmt, |
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172 | const void *from); |
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173 | |||
174 | static int |
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175 | floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from) |
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176 | { |
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177 | /* In the i387 double-extended format, if the exponent is all ones, |
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178 | then the integer bit must be set. If the exponent is neither 0 |
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179 | nor ~0, the intbit must also be set. Only if the exponent is |
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180 | zero can it be zero, and then it must be zero. */ |
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181 | unsigned long exponent, int_bit; |
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182 | const unsigned char *ufrom = (const unsigned char *) from; |
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183 | |||
184 | exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, |
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185 | fmt->exp_start, fmt->exp_len); |
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186 | int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize, |
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187 | fmt->man_start, 1); |
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188 | |||
189 | if ((exponent == 0) != (int_bit == 0)) |
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190 | return 0; |
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191 | else |
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192 | return 1; |
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193 | } |
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194 | |||
195 | const struct floatformat floatformat_i387_ext = |
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196 | { |
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197 | floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64, |
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198 | floatformat_intbit_yes, |
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199 | "floatformat_i387_ext", |
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200 | floatformat_i387_ext_is_valid, |
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201 | NULL |
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202 | }; |
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203 | const struct floatformat floatformat_m68881_ext = |
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204 | { |
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205 | /* Note that the bits from 16 to 31 are unused. */ |
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206 | floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64, |
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207 | floatformat_intbit_yes, |
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208 | "floatformat_m68881_ext", |
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209 | floatformat_always_valid, |
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210 | NULL |
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211 | }; |
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212 | const struct floatformat floatformat_i960_ext = |
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213 | { |
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214 | /* Note that the bits from 0 to 15 are unused. */ |
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215 | floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64, |
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216 | floatformat_intbit_yes, |
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217 | "floatformat_i960_ext", |
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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_m88110_ext = |
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222 | { |
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223 | floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64, |
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224 | floatformat_intbit_yes, |
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225 | "floatformat_m88110_ext", |
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226 | floatformat_always_valid, |
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227 | NULL |
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228 | }; |
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229 | const struct floatformat floatformat_m88110_harris_ext = |
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230 | { |
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231 | /* Harris uses raw format 128 bytes long, but the number is just an ieee |
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232 | double, and the last 64 bits are wasted. */ |
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233 | floatformat_big,128, 0, 1, 11, 0x3ff, 0x7ff, 12, 52, |
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234 | floatformat_intbit_no, |
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235 | "floatformat_m88110_ext_harris", |
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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_arm_ext_big = |
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240 | { |
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241 | /* Bits 1 to 16 are unused. */ |
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242 | floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64, |
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243 | floatformat_intbit_yes, |
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244 | "floatformat_arm_ext_big", |
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245 | floatformat_always_valid, |
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246 | NULL |
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247 | }; |
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248 | const struct floatformat floatformat_arm_ext_littlebyte_bigword = |
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249 | { |
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250 | /* Bits 1 to 16 are unused. */ |
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251 | floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64, |
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252 | floatformat_intbit_yes, |
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253 | "floatformat_arm_ext_littlebyte_bigword", |
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254 | floatformat_always_valid, |
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255 | NULL |
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256 | }; |
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257 | const struct floatformat floatformat_ia64_spill_big = |
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258 | { |
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259 | floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64, |
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260 | floatformat_intbit_yes, |
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261 | "floatformat_ia64_spill_big", |
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262 | floatformat_always_valid, |
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263 | NULL |
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264 | }; |
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265 | const struct floatformat floatformat_ia64_spill_little = |
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266 | { |
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267 | floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64, |
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268 | floatformat_intbit_yes, |
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269 | "floatformat_ia64_spill_little", |
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270 | floatformat_always_valid, |
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271 | NULL |
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272 | }; |
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273 | const struct floatformat floatformat_ia64_quad_big = |
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274 | { |
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275 | floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112, |
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276 | floatformat_intbit_no, |
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277 | "floatformat_ia64_quad_big", |
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278 | floatformat_always_valid, |
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279 | NULL |
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280 | }; |
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281 | const struct floatformat floatformat_ia64_quad_little = |
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282 | { |
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283 | floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112, |
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284 | floatformat_intbit_no, |
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285 | "floatformat_ia64_quad_little", |
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286 | floatformat_always_valid, |
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287 | NULL |
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288 | }; |
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289 | |||
290 | static int |
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291 | floatformat_ibm_long_double_is_valid (const struct floatformat *fmt, |
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292 | const void *from) |
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293 | { |
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294 | const unsigned char *ufrom = (const unsigned char *) from; |
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295 | const struct floatformat *hfmt = fmt->split_half; |
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296 | long top_exp, bot_exp; |
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297 | int top_nan = 0; |
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298 | |||
299 | top_exp = get_field (ufrom, hfmt->byteorder, hfmt->totalsize, |
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300 | hfmt->exp_start, hfmt->exp_len); |
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301 | bot_exp = get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize, |
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302 | hfmt->exp_start, hfmt->exp_len); |
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303 | |||
304 | if ((unsigned long) top_exp == hfmt->exp_nan) |
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305 | top_nan = mant_bits_set (hfmt, ufrom); |
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306 | |||
307 | /* A NaN is valid with any low part. */ |
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308 | if (top_nan) |
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309 | return 1; |
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310 | |||
311 | /* An infinity, zero or denormal requires low part 0 (positive or |
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312 | negative). */ |
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313 | if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0) |
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314 | { |
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315 | if (bot_exp != 0) |
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316 | return 0; |
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317 | |||
318 | return !mant_bits_set (hfmt, ufrom + 8); |
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319 | } |
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320 | |||
321 | /* The top part is now a finite normal value. The long double value |
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322 | is the sum of the two parts, and the top part must equal the |
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323 | result of rounding the long double value to nearest double. Thus |
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324 | the bottom part must be <= 0.5ulp of the top part in absolute |
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325 | value, and if it is < 0.5ulp then the long double is definitely |
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326 | valid. */ |
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327 | if (bot_exp < top_exp - 53) |
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328 | return 1; |
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329 | if (bot_exp > top_exp - 53 && bot_exp != 0) |
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330 | return 0; |
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331 | if (bot_exp == 0) |
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332 | { |
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333 | /* The bottom part is 0 or denormal. Determine which, and if |
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334 | denormal the first two set bits. */ |
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335 | int first_bit = -1, second_bit = -1, cur_bit; |
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336 | for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++) |
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337 | if (get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize, |
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338 | hfmt->man_start + cur_bit, 1)) |
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339 | { |
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340 | if (first_bit == -1) |
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341 | first_bit = cur_bit; |
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342 | else |
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343 | { |
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344 | second_bit = cur_bit; |
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345 | break; |
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346 | } |
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347 | } |
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348 | /* Bottom part 0 is OK. */ |
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349 | if (first_bit == -1) |
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350 | return 1; |
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351 | /* The real exponent of the bottom part is -first_bit. */ |
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352 | if (-first_bit < top_exp - 53) |
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353 | return 1; |
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354 | if (-first_bit > top_exp - 53) |
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355 | return 0; |
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356 | /* The bottom part is at least 0.5ulp of the top part. For this |
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357 | to be OK, the bottom part must be exactly 0.5ulp (i.e. no |
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358 | more bits set) and the top part must have last bit 0. */ |
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359 | if (second_bit != -1) |
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360 | return 0; |
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361 | return !get_field (ufrom, hfmt->byteorder, hfmt->totalsize, |
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362 | hfmt->man_start + hfmt->man_len - 1, 1); |
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363 | } |
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364 | else |
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365 | { |
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366 | /* The bottom part is at least 0.5ulp of the top part. For this |
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367 | to be OK, it must be exactly 0.5ulp (i.e. no explicit bits |
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368 | set) and the top part must have last bit 0. */ |
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369 | if (get_field (ufrom, hfmt->byteorder, hfmt->totalsize, |
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370 | hfmt->man_start + hfmt->man_len - 1, 1)) |
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371 | return 0; |
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372 | return !mant_bits_set (hfmt, ufrom + 8); |
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373 | } |
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374 | } |
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375 | |||
376 | const struct floatformat floatformat_ibm_long_double_big = |
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377 | { |
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378 | floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52, |
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379 | floatformat_intbit_no, |
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380 | "floatformat_ibm_long_double_big", |
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381 | floatformat_ibm_long_double_is_valid, |
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382 | &floatformat_ieee_double_big |
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383 | }; |
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384 | |||
385 | const struct floatformat floatformat_ibm_long_double_little = |
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386 | { |
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387 | floatformat_little, 128, 0, 1, 11, 1023, 2047, 12, 52, |
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388 | floatformat_intbit_no, |
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389 | "floatformat_ibm_long_double_little", |
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390 | floatformat_ibm_long_double_is_valid, |
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391 | &floatformat_ieee_double_little |
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392 | }; |
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393 | |||
394 | |||
395 | #ifndef min |
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396 | #define min(a, b) ((a) < (b) ? (a) : (b)) |
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397 | #endif |
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398 | |||
399 | /* Return 1 if any bits are explicitly set in the mantissa of UFROM, |
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400 | format FMT, 0 otherwise. */ |
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401 | static int |
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402 | mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom) |
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403 | { |
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404 | unsigned int mant_bits, mant_off; |
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405 | int mant_bits_left; |
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406 | |||
407 | mant_off = fmt->man_start; |
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408 | mant_bits_left = fmt->man_len; |
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409 | while (mant_bits_left > 0) |
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410 | { |
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411 | mant_bits = min (mant_bits_left, 32); |
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412 | |||
413 | if (get_field (ufrom, fmt->byteorder, fmt->totalsize, |
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414 | mant_off, mant_bits) != 0) |
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415 | return 1; |
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416 | |||
417 | mant_off += mant_bits; |
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418 | mant_bits_left -= mant_bits; |
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419 | } |
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420 | return 0; |
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421 | } |
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422 | |||
423 | /* Extract a field which starts at START and is LEN bits long. DATA and |
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424 | TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ |
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425 | static unsigned long |
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426 | get_field (const unsigned char *data, enum floatformat_byteorders order, |
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427 | unsigned int total_len, unsigned int start, unsigned int len) |
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428 | { |
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429 | unsigned long result = 0; |
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430 | unsigned int cur_byte; |
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431 | int lo_bit, hi_bit, cur_bitshift = 0; |
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432 | int nextbyte = (order == floatformat_little) ? 1 : -1; |
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433 | |||
434 | /* Start is in big-endian bit order! Fix that first. */ |
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435 | start = total_len - (start + len); |
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436 | |||
437 | /* Start at the least significant part of the field. */ |
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438 | if (order == floatformat_little) |
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439 | cur_byte = start / FLOATFORMAT_CHAR_BIT; |
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440 | else |
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441 | cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; |
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442 | |||
443 | lo_bit = start % FLOATFORMAT_CHAR_BIT; |
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444 | hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); |
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445 | |||
446 | do |
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447 | { |
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448 | unsigned int shifted = *(data + cur_byte) >> lo_bit; |
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449 | unsigned int bits = hi_bit - lo_bit; |
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450 | unsigned int mask = (1 << bits) - 1; |
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451 | result |= (shifted & mask) << cur_bitshift; |
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452 | len -= bits; |
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453 | cur_bitshift += bits; |
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454 | cur_byte += nextbyte; |
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455 | lo_bit = 0; |
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456 | hi_bit = min (len, FLOATFORMAT_CHAR_BIT); |
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457 | } |
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458 | while (len != 0); |
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459 | |||
460 | return result; |
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461 | } |
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462 | |||
463 | /* Convert from FMT to a double. |
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464 | FROM is the address of the extended float. |
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465 | Store the double in *TO. */ |
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466 | |||
467 | void |
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468 | floatformat_to_double (const struct floatformat *fmt, |
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469 | const void *from, double *to) |
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470 | { |
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471 | const unsigned char *ufrom = (const unsigned char *) from; |
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472 | double dto; |
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473 | long exponent; |
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474 | unsigned long mant; |
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475 | unsigned int mant_bits, mant_off; |
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476 | int mant_bits_left; |
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477 | |||
478 | /* Split values are not handled specially, since the top half has |
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479 | the correctly rounded double value (in the only supported case of |
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480 | split values). */ |
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481 | |||
482 | exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, |
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483 | fmt->exp_start, fmt->exp_len); |
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484 | |||
485 | /* If the exponent indicates a NaN, we don't have information to |
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486 | decide what to do. So we handle it like IEEE, except that we |
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487 | don't try to preserve the type of NaN. FIXME. */ |
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488 | if ((unsigned long) exponent == fmt->exp_nan) |
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489 | { |
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490 | int nan = mant_bits_set (fmt, ufrom); |
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491 | |||
492 | /* On certain systems (such as GNU/Linux), the use of the |
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493 | INFINITY macro below may generate a warning that can not be |
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494 | silenced due to a bug in GCC (PR preprocessor/11931). The |
||
495 | preprocessor fails to recognise the __extension__ keyword in |
||
496 | conjunction with the GNU/C99 extension for hexadecimal |
||
497 | floating point constants and will issue a warning when |
||
498 | compiling with -pedantic. */ |
||
499 | if (nan) |
||
500 | dto = NAN; |
||
501 | else |
||
502 | dto = INFINITY; |
||
503 | |||
504 | if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) |
||
505 | dto = -dto; |
||
506 | |||
507 | *to = dto; |
||
508 | |||
509 | return; |
||
510 | } |
||
511 | |||
512 | mant_bits_left = fmt->man_len; |
||
513 | mant_off = fmt->man_start; |
||
514 | dto = 0.0; |
||
515 | |||
516 | /* Build the result algebraically. Might go infinite, underflow, etc; |
||
517 | who cares. */ |
||
518 | |||
519 | /* For denorms use minimum exponent. */ |
||
520 | if (exponent == 0) |
||
521 | exponent = 1 - fmt->exp_bias; |
||
522 | else |
||
523 | { |
||
524 | exponent -= fmt->exp_bias; |
||
525 | |||
526 | /* If this format uses a hidden bit, explicitly add it in now. |
||
527 | Otherwise, increment the exponent by one to account for the |
||
528 | integer bit. */ |
||
529 | |||
530 | if (fmt->intbit == floatformat_intbit_no) |
||
531 | dto = ldexp (1.0, exponent); |
||
532 | else |
||
533 | exponent++; |
||
534 | } |
||
535 | |||
536 | while (mant_bits_left > 0) |
||
537 | { |
||
538 | mant_bits = min (mant_bits_left, 32); |
||
539 | |||
540 | mant = get_field (ufrom, fmt->byteorder, fmt->totalsize, |
||
541 | mant_off, mant_bits); |
||
542 | |||
543 | dto += ldexp ((double) mant, exponent - mant_bits); |
||
544 | exponent -= mant_bits; |
||
545 | mant_off += mant_bits; |
||
546 | mant_bits_left -= mant_bits; |
||
547 | } |
||
548 | |||
549 | /* Negate it if negative. */ |
||
550 | if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) |
||
551 | dto = -dto; |
||
552 | *to = dto; |
||
553 | } |
||
554 | |||
555 | static void put_field (unsigned char *, enum floatformat_byteorders, |
||
556 | unsigned int, |
||
557 | unsigned int, |
||
558 | unsigned int, |
||
559 | unsigned long); |
||
560 | |||
561 | /* Set a field which starts at START and is LEN bits long. DATA and |
||
562 | TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ |
||
563 | static void |
||
564 | put_field (unsigned char *data, enum floatformat_byteorders order, |
||
565 | unsigned int total_len, unsigned int start, unsigned int len, |
||
566 | unsigned long stuff_to_put) |
||
567 | { |
||
568 | unsigned int cur_byte; |
||
569 | int lo_bit, hi_bit; |
||
570 | int nextbyte = (order == floatformat_little) ? 1 : -1; |
||
571 | |||
572 | /* Start is in big-endian bit order! Fix that first. */ |
||
573 | start = total_len - (start + len); |
||
574 | |||
575 | /* Start at the least significant part of the field. */ |
||
576 | if (order == floatformat_little) |
||
577 | cur_byte = start / FLOATFORMAT_CHAR_BIT; |
||
578 | else |
||
579 | cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; |
||
580 | |||
581 | lo_bit = start % FLOATFORMAT_CHAR_BIT; |
||
582 | hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); |
||
583 | |||
584 | do |
||
585 | { |
||
586 | unsigned char *byte_ptr = data + cur_byte; |
||
587 | unsigned int bits = hi_bit - lo_bit; |
||
588 | unsigned int mask = ((1 << bits) - 1) << lo_bit; |
||
589 | *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask); |
||
590 | stuff_to_put >>= bits; |
||
591 | len -= bits; |
||
592 | cur_byte += nextbyte; |
||
593 | lo_bit = 0; |
||
594 | hi_bit = min (len, FLOATFORMAT_CHAR_BIT); |
||
595 | } |
||
596 | while (len != 0); |
||
597 | } |
||
598 | |||
599 | /* The converse: convert the double *FROM to an extended float |
||
600 | and store where TO points. Neither FROM nor TO have any alignment |
||
601 | restrictions. */ |
||
602 | |||
603 | void |
||
604 | floatformat_from_double (const struct floatformat *fmt, |
||
605 | const double *from, void *to) |
||
606 | { |
||
607 | double dfrom; |
||
608 | int exponent; |
||
609 | double mant; |
||
610 | unsigned int mant_bits, mant_off; |
||
611 | int mant_bits_left; |
||
612 | unsigned char *uto = (unsigned char *) to; |
||
613 | |||
614 | dfrom = *from; |
||
615 | memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT); |
||
616 | |||
617 | /* Split values are not handled specially, since a bottom half of |
||
618 | zero is correct for any value representable as double (in the |
||
619 | only supported case of split values). */ |
||
620 | |||
621 | /* If negative, set the sign bit. */ |
||
622 | if (dfrom < 0) |
||
623 | { |
||
624 | put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1); |
||
625 | dfrom = -dfrom; |
||
626 | } |
||
627 | |||
628 | if (dfrom == 0) |
||
629 | { |
||
630 | /* 0.0. */ |
||
631 | return; |
||
632 | } |
||
633 | |||
634 | if (dfrom != dfrom) |
||
635 | { |
||
636 | /* NaN. */ |
||
637 | put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, |
||
638 | fmt->exp_len, fmt->exp_nan); |
||
639 | /* Be sure it's not infinity, but NaN value is irrelevant. */ |
||
640 | put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start, |
||
641 | 32, 1); |
||
642 | return; |
||
643 | } |
||
644 | |||
645 | if (dfrom + dfrom == dfrom) |
||
646 | { |
||
647 | /* This can only happen for an infinite value (or zero, which we |
||
648 | already handled above). */ |
||
649 | put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, |
||
650 | fmt->exp_len, fmt->exp_nan); |
||
651 | return; |
||
652 | } |
||
653 | |||
654 | mant = frexp (dfrom, &exponent); |
||
655 | if (exponent + fmt->exp_bias - 1 > 0) |
||
656 | put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, |
||
657 | fmt->exp_len, exponent + fmt->exp_bias - 1); |
||
658 | else |
||
659 | { |
||
660 | /* Handle a denormalized number. FIXME: What should we do for |
||
661 | non-IEEE formats? */ |
||
662 | put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, |
||
663 | fmt->exp_len, 0); |
||
664 | mant = ldexp (mant, exponent + fmt->exp_bias - 1); |
||
665 | } |
||
666 | |||
667 | mant_bits_left = fmt->man_len; |
||
668 | mant_off = fmt->man_start; |
||
669 | while (mant_bits_left > 0) |
||
670 | { |
||
671 | unsigned long mant_long; |
||
672 | mant_bits = mant_bits_left < 32 ? mant_bits_left : 32; |
||
673 | |||
674 | mant *= 4294967296.0; |
||
675 | mant_long = (unsigned long)mant; |
||
676 | mant -= mant_long; |
||
677 | |||
678 | /* If the integer bit is implicit, and we are not creating a |
||
679 | denormalized number, then we need to discard it. */ |
||
680 | if ((unsigned int) mant_bits_left == fmt->man_len |
||
681 | && fmt->intbit == floatformat_intbit_no |
||
682 | && exponent + fmt->exp_bias - 1 > 0) |
||
683 | { |
||
684 | mant_long &= 0x7fffffff; |
||
685 | mant_bits -= 1; |
||
686 | } |
||
687 | else if (mant_bits < 32) |
||
688 | { |
||
689 | /* The bits we want are in the most significant MANT_BITS bits of |
||
690 | mant_long. Move them to the least significant. */ |
||
691 | mant_long >>= 32 - mant_bits; |
||
692 | } |
||
693 | |||
694 | put_field (uto, fmt->byteorder, fmt->totalsize, |
||
695 | mant_off, mant_bits, mant_long); |
||
696 | mant_off += mant_bits; |
||
697 | mant_bits_left -= mant_bits; |
||
698 | } |
||
699 | } |
||
700 | |||
701 | /* Return non-zero iff the data at FROM is a valid number in format FMT. */ |
||
702 | |||
703 | int |
||
704 | floatformat_is_valid (const struct floatformat *fmt, const void *from) |
||
705 | { |
||
706 | return fmt->is_valid (fmt, from); |
||
707 | } |
||
708 | |||
709 | |||
710 | #ifdef IEEE_DEBUG |
||
711 | |||
712 | #include |
||
713 | |||
714 | /* This is to be run on a host which uses IEEE floating point. */ |
||
715 | |||
716 | void |
||
717 | ieee_test (double n) |
||
718 | { |
||
719 | double result; |
||
720 | |||
721 | floatformat_to_double (&floatformat_ieee_double_little, &n, &result); |
||
722 | if ((n != result && (! isnan (n) || ! isnan (result))) |
||
723 | || (n < 0 && result >= 0) |
||
724 | || (n >= 0 && result < 0)) |
||
725 | printf ("Differ(to): %.20g -> %.20g\n", n, result); |
||
726 | |||
727 | floatformat_from_double (&floatformat_ieee_double_little, &n, &result); |
||
728 | if ((n != result && (! isnan (n) || ! isnan (result))) |
||
729 | || (n < 0 && result >= 0) |
||
730 | || (n >= 0 && result < 0)) |
||
731 | printf ("Differ(from): %.20g -> %.20g\n", n, result); |
||
732 | |||
733 | #if 0 |
||
734 | { |
||
735 | char exten[16]; |
||
736 | |||
737 | floatformat_from_double (&floatformat_m68881_ext, &n, exten); |
||
738 | floatformat_to_double (&floatformat_m68881_ext, exten, &result); |
||
739 | if (n != result) |
||
740 | printf ("Differ(to+from): %.20g -> %.20g\n", n, result); |
||
741 | } |
||
742 | #endif |
||
743 | |||
744 | #if IEEE_DEBUG > 1 |
||
745 | /* This is to be run on a host which uses 68881 format. */ |
||
746 | { |
||
747 | long double ex = *(long double *)exten; |
||
748 | if (ex != n) |
||
749 | printf ("Differ(from vs. extended): %.20g\n", n); |
||
750 | } |
||
751 | #endif |
||
752 | } |
||
753 | |||
754 | int |
||
755 | main (void) |
||
756 | { |
||
757 | ieee_test (0.0); |
||
758 | ieee_test (0.5); |
||
759 | ieee_test (1.1); |
||
760 | ieee_test (256.0); |
||
761 | ieee_test (0.12345); |
||
762 | ieee_test (234235.78907234); |
||
763 | ieee_test (-512.0); |
||
764 | ieee_test (-0.004321); |
||
765 | ieee_test (1.2E-70); |
||
766 | ieee_test (1.2E-316); |
||
767 | ieee_test (4.9406564584124654E-324); |
||
768 | ieee_test (- 4.9406564584124654E-324); |
||
769 | ieee_test (- 0.0); |
||
770 | ieee_test (- INFINITY); |
||
771 | ieee_test (- NAN); |
||
772 | ieee_test (INFINITY); |
||
773 | ieee_test (NAN); |
||
774 | return 0; |
||
775 | } |
||
776 | #endif>>>>>>>><>><>><>><>><>>>>>>=> |