Mercurial > hg > CbC > CbC_gcc
annotate libiberty/floatformat.c @ 67:f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
| author | nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp> |
|---|---|
| date | Tue, 22 Mar 2011 17:18:12 +0900 |
| parents | a06113de4d67 |
| children | 04ced10e8804 |
| rev | line source |
|---|---|
| 0 | 1 /* IEEE floating point support routines, for GDB, the GNU Debugger. |
|
67
f6334be47118
update gcc from gcc-4.6-20100522 to gcc-4.6-20110318
nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
0
diff
changeset
|
2 Copyright 1991, 1994, 1999, 2000, 2003, 2005, 2006, 2010 |
| 0 | 3 Free Software Foundation, Inc. |
| 4 | |
| 5 This file is part of GDB. | |
| 6 | |
| 7 This program is free software; you can redistribute it and/or modify | |
| 8 it under the terms of the GNU General Public License as published by | |
| 9 the Free Software Foundation; either version 2 of the License, or | |
| 10 (at your option) any later version. | |
| 11 | |
| 12 This program is distributed in the hope that it will be useful, | |
| 13 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 15 GNU General Public License for more details. | |
| 16 | |
| 17 You should have received a copy of the GNU General Public License | |
| 18 along with this program; if not, write to the Free Software | |
| 19 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ | |
| 20 | |
| 21 /* This is needed to pick up the NAN macro on some systems. */ | |
| 22 #define _GNU_SOURCE | |
| 23 | |
| 24 #ifdef HAVE_CONFIG_H | |
| 25 #include "config.h" | |
| 26 #endif | |
| 27 | |
| 28 #include <math.h> | |
| 29 | |
| 30 #ifdef HAVE_STRING_H | |
| 31 #include <string.h> | |
| 32 #endif | |
| 33 | |
| 34 /* On some platforms, <float.h> provides DBL_QNAN. */ | |
| 35 #ifdef STDC_HEADERS | |
| 36 #include <float.h> | |
| 37 #endif | |
| 38 | |
| 39 #include "ansidecl.h" | |
| 40 #include "libiberty.h" | |
| 41 #include "floatformat.h" | |
| 42 | |
| 43 #ifndef INFINITY | |
| 44 #ifdef HUGE_VAL | |
| 45 #define INFINITY HUGE_VAL | |
| 46 #else | |
| 47 #define INFINITY (1.0 / 0.0) | |
| 48 #endif | |
| 49 #endif | |
| 50 | |
| 51 #ifndef NAN | |
| 52 #ifdef DBL_QNAN | |
| 53 #define NAN DBL_QNAN | |
| 54 #else | |
| 55 #define NAN (0.0 / 0.0) | |
| 56 #endif | |
| 57 #endif | |
| 58 | |
| 59 static int mant_bits_set (const struct floatformat *, const unsigned char *); | |
| 60 static unsigned long get_field (const unsigned char *, | |
| 61 enum floatformat_byteorders, | |
| 62 unsigned int, | |
| 63 unsigned int, | |
| 64 unsigned int); | |
| 65 static int floatformat_always_valid (const struct floatformat *fmt, | |
| 66 const void *from); | |
| 67 | |
| 68 static int | |
| 69 floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED, | |
| 70 const void *from ATTRIBUTE_UNUSED) | |
| 71 { | |
| 72 return 1; | |
| 73 } | |
| 74 | |
| 75 /* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not | |
| 76 going to bother with trying to muck around with whether it is defined in | |
| 77 a system header, what we do if not, etc. */ | |
| 78 #define FLOATFORMAT_CHAR_BIT 8 | |
| 79 | |
|
67
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nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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changeset
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80 /* floatformats for IEEE half, single and double, big and little endian. */ |
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81 const struct floatformat floatformat_ieee_half_big = |
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82 { |
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83 floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10, |
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84 floatformat_intbit_no, |
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85 "floatformat_ieee_half_big", |
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86 floatformat_always_valid, |
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87 NULL |
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nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
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88 }; |
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nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
parents:
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89 const struct floatformat floatformat_ieee_half_little = |
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90 { |
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91 floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10, |
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92 floatformat_intbit_no, |
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93 "floatformat_ieee_half_little", |
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94 floatformat_always_valid, |
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95 NULL |
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nobuyasu <dimolto@cr.ie.u-ryukyu.ac.jp>
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96 }; |
| 0 | 97 const struct floatformat floatformat_ieee_single_big = |
| 98 { | |
| 99 floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23, | |
| 100 floatformat_intbit_no, | |
| 101 "floatformat_ieee_single_big", | |
| 102 floatformat_always_valid, | |
| 103 NULL | |
| 104 }; | |
| 105 const struct floatformat floatformat_ieee_single_little = | |
| 106 { | |
| 107 floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23, | |
| 108 floatformat_intbit_no, | |
| 109 "floatformat_ieee_single_little", | |
| 110 floatformat_always_valid, | |
| 111 NULL | |
| 112 }; | |
| 113 const struct floatformat floatformat_ieee_double_big = | |
| 114 { | |
| 115 floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52, | |
| 116 floatformat_intbit_no, | |
| 117 "floatformat_ieee_double_big", | |
| 118 floatformat_always_valid, | |
| 119 NULL | |
| 120 }; | |
| 121 const struct floatformat floatformat_ieee_double_little = | |
| 122 { | |
| 123 floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52, | |
| 124 floatformat_intbit_no, | |
| 125 "floatformat_ieee_double_little", | |
| 126 floatformat_always_valid, | |
| 127 NULL | |
| 128 }; | |
| 129 | |
| 130 /* floatformat for IEEE double, little endian byte order, with big endian word | |
| 131 ordering, as on the ARM. */ | |
| 132 | |
| 133 const struct floatformat floatformat_ieee_double_littlebyte_bigword = | |
| 134 { | |
| 135 floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52, | |
| 136 floatformat_intbit_no, | |
| 137 "floatformat_ieee_double_littlebyte_bigword", | |
| 138 floatformat_always_valid, | |
| 139 NULL | |
| 140 }; | |
| 141 | |
| 142 /* floatformat for VAX. Not quite IEEE, but close enough. */ | |
| 143 | |
| 144 const struct floatformat floatformat_vax_f = | |
| 145 { | |
| 146 floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23, | |
| 147 floatformat_intbit_no, | |
| 148 "floatformat_vax_f", | |
| 149 floatformat_always_valid, | |
| 150 NULL | |
| 151 }; | |
| 152 const struct floatformat floatformat_vax_d = | |
| 153 { | |
| 154 floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55, | |
| 155 floatformat_intbit_no, | |
| 156 "floatformat_vax_d", | |
| 157 floatformat_always_valid, | |
| 158 NULL | |
| 159 }; | |
| 160 const struct floatformat floatformat_vax_g = | |
| 161 { | |
| 162 floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52, | |
| 163 floatformat_intbit_no, | |
| 164 "floatformat_vax_g", | |
| 165 floatformat_always_valid, | |
| 166 NULL | |
| 167 }; | |
| 168 | |
| 169 static int floatformat_i387_ext_is_valid (const struct floatformat *fmt, | |
| 170 const void *from); | |
| 171 | |
| 172 static int | |
| 173 floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from) | |
| 174 { | |
| 175 /* In the i387 double-extended format, if the exponent is all ones, | |
| 176 then the integer bit must be set. If the exponent is neither 0 | |
| 177 nor ~0, the intbit must also be set. Only if the exponent is | |
| 178 zero can it be zero, and then it must be zero. */ | |
| 179 unsigned long exponent, int_bit; | |
| 180 const unsigned char *ufrom = (const unsigned char *) from; | |
| 181 | |
| 182 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, | |
| 183 fmt->exp_start, fmt->exp_len); | |
| 184 int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize, | |
| 185 fmt->man_start, 1); | |
| 186 | |
| 187 if ((exponent == 0) != (int_bit == 0)) | |
| 188 return 0; | |
| 189 else | |
| 190 return 1; | |
| 191 } | |
| 192 | |
| 193 const struct floatformat floatformat_i387_ext = | |
| 194 { | |
| 195 floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64, | |
| 196 floatformat_intbit_yes, | |
| 197 "floatformat_i387_ext", | |
| 198 floatformat_i387_ext_is_valid, | |
| 199 NULL | |
| 200 }; | |
| 201 const struct floatformat floatformat_m68881_ext = | |
| 202 { | |
| 203 /* Note that the bits from 16 to 31 are unused. */ | |
| 204 floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64, | |
| 205 floatformat_intbit_yes, | |
| 206 "floatformat_m68881_ext", | |
| 207 floatformat_always_valid, | |
| 208 NULL | |
| 209 }; | |
| 210 const struct floatformat floatformat_i960_ext = | |
| 211 { | |
| 212 /* Note that the bits from 0 to 15 are unused. */ | |
| 213 floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64, | |
| 214 floatformat_intbit_yes, | |
| 215 "floatformat_i960_ext", | |
| 216 floatformat_always_valid, | |
| 217 NULL | |
| 218 }; | |
| 219 const struct floatformat floatformat_m88110_ext = | |
| 220 { | |
| 221 floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64, | |
| 222 floatformat_intbit_yes, | |
| 223 "floatformat_m88110_ext", | |
| 224 floatformat_always_valid, | |
| 225 NULL | |
| 226 }; | |
| 227 const struct floatformat floatformat_m88110_harris_ext = | |
| 228 { | |
| 229 /* Harris uses raw format 128 bytes long, but the number is just an ieee | |
| 230 double, and the last 64 bits are wasted. */ | |
| 231 floatformat_big,128, 0, 1, 11, 0x3ff, 0x7ff, 12, 52, | |
| 232 floatformat_intbit_no, | |
| 233 "floatformat_m88110_ext_harris", | |
| 234 floatformat_always_valid, | |
| 235 NULL | |
| 236 }; | |
| 237 const struct floatformat floatformat_arm_ext_big = | |
| 238 { | |
| 239 /* Bits 1 to 16 are unused. */ | |
| 240 floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64, | |
| 241 floatformat_intbit_yes, | |
| 242 "floatformat_arm_ext_big", | |
| 243 floatformat_always_valid, | |
| 244 NULL | |
| 245 }; | |
| 246 const struct floatformat floatformat_arm_ext_littlebyte_bigword = | |
| 247 { | |
| 248 /* Bits 1 to 16 are unused. */ | |
| 249 floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64, | |
| 250 floatformat_intbit_yes, | |
| 251 "floatformat_arm_ext_littlebyte_bigword", | |
| 252 floatformat_always_valid, | |
| 253 NULL | |
| 254 }; | |
| 255 const struct floatformat floatformat_ia64_spill_big = | |
| 256 { | |
| 257 floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64, | |
| 258 floatformat_intbit_yes, | |
| 259 "floatformat_ia64_spill_big", | |
| 260 floatformat_always_valid, | |
| 261 NULL | |
| 262 }; | |
| 263 const struct floatformat floatformat_ia64_spill_little = | |
| 264 { | |
| 265 floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64, | |
| 266 floatformat_intbit_yes, | |
| 267 "floatformat_ia64_spill_little", | |
| 268 floatformat_always_valid, | |
| 269 NULL | |
| 270 }; | |
| 271 const struct floatformat floatformat_ia64_quad_big = | |
| 272 { | |
| 273 floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112, | |
| 274 floatformat_intbit_no, | |
| 275 "floatformat_ia64_quad_big", | |
| 276 floatformat_always_valid, | |
| 277 NULL | |
| 278 }; | |
| 279 const struct floatformat floatformat_ia64_quad_little = | |
| 280 { | |
| 281 floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112, | |
| 282 floatformat_intbit_no, | |
| 283 "floatformat_ia64_quad_little", | |
| 284 floatformat_always_valid, | |
| 285 NULL | |
| 286 }; | |
| 287 | |
| 288 static int | |
| 289 floatformat_ibm_long_double_is_valid (const struct floatformat *fmt, | |
| 290 const void *from) | |
| 291 { | |
| 292 const unsigned char *ufrom = (const unsigned char *) from; | |
| 293 const struct floatformat *hfmt = fmt->split_half; | |
| 294 long top_exp, bot_exp; | |
| 295 int top_nan = 0; | |
| 296 | |
| 297 top_exp = get_field (ufrom, hfmt->byteorder, hfmt->totalsize, | |
| 298 hfmt->exp_start, hfmt->exp_len); | |
| 299 bot_exp = get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize, | |
| 300 hfmt->exp_start, hfmt->exp_len); | |
| 301 | |
| 302 if ((unsigned long) top_exp == hfmt->exp_nan) | |
| 303 top_nan = mant_bits_set (hfmt, ufrom); | |
| 304 | |
| 305 /* A NaN is valid with any low part. */ | |
| 306 if (top_nan) | |
| 307 return 1; | |
| 308 | |
| 309 /* An infinity, zero or denormal requires low part 0 (positive or | |
| 310 negative). */ | |
| 311 if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0) | |
| 312 { | |
| 313 if (bot_exp != 0) | |
| 314 return 0; | |
| 315 | |
| 316 return !mant_bits_set (hfmt, ufrom + 8); | |
| 317 } | |
| 318 | |
| 319 /* The top part is now a finite normal value. The long double value | |
| 320 is the sum of the two parts, and the top part must equal the | |
| 321 result of rounding the long double value to nearest double. Thus | |
| 322 the bottom part must be <= 0.5ulp of the top part in absolute | |
| 323 value, and if it is < 0.5ulp then the long double is definitely | |
| 324 valid. */ | |
| 325 if (bot_exp < top_exp - 53) | |
| 326 return 1; | |
| 327 if (bot_exp > top_exp - 53 && bot_exp != 0) | |
| 328 return 0; | |
| 329 if (bot_exp == 0) | |
| 330 { | |
| 331 /* The bottom part is 0 or denormal. Determine which, and if | |
| 332 denormal the first two set bits. */ | |
| 333 int first_bit = -1, second_bit = -1, cur_bit; | |
| 334 for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++) | |
| 335 if (get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize, | |
| 336 hfmt->man_start + cur_bit, 1)) | |
| 337 { | |
| 338 if (first_bit == -1) | |
| 339 first_bit = cur_bit; | |
| 340 else | |
| 341 { | |
| 342 second_bit = cur_bit; | |
| 343 break; | |
| 344 } | |
| 345 } | |
| 346 /* Bottom part 0 is OK. */ | |
| 347 if (first_bit == -1) | |
| 348 return 1; | |
| 349 /* The real exponent of the bottom part is -first_bit. */ | |
| 350 if (-first_bit < top_exp - 53) | |
| 351 return 1; | |
| 352 if (-first_bit > top_exp - 53) | |
| 353 return 0; | |
| 354 /* The bottom part is at least 0.5ulp of the top part. For this | |
| 355 to be OK, the bottom part must be exactly 0.5ulp (i.e. no | |
| 356 more bits set) and the top part must have last bit 0. */ | |
| 357 if (second_bit != -1) | |
| 358 return 0; | |
| 359 return !get_field (ufrom, hfmt->byteorder, hfmt->totalsize, | |
| 360 hfmt->man_start + hfmt->man_len - 1, 1); | |
| 361 } | |
| 362 else | |
| 363 { | |
| 364 /* The bottom part is at least 0.5ulp of the top part. For this | |
| 365 to be OK, it must be exactly 0.5ulp (i.e. no explicit bits | |
| 366 set) and the top part must have last bit 0. */ | |
| 367 if (get_field (ufrom, hfmt->byteorder, hfmt->totalsize, | |
| 368 hfmt->man_start + hfmt->man_len - 1, 1)) | |
| 369 return 0; | |
| 370 return !mant_bits_set (hfmt, ufrom + 8); | |
| 371 } | |
| 372 } | |
| 373 | |
| 374 const struct floatformat floatformat_ibm_long_double = | |
| 375 { | |
| 376 floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52, | |
| 377 floatformat_intbit_no, | |
| 378 "floatformat_ibm_long_double", | |
| 379 floatformat_ibm_long_double_is_valid, | |
| 380 &floatformat_ieee_double_big | |
| 381 }; | |
| 382 | |
| 383 | |
| 384 #ifndef min | |
| 385 #define min(a, b) ((a) < (b) ? (a) : (b)) | |
| 386 #endif | |
| 387 | |
| 388 /* Return 1 if any bits are explicitly set in the mantissa of UFROM, | |
| 389 format FMT, 0 otherwise. */ | |
| 390 static int | |
| 391 mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom) | |
| 392 { | |
| 393 unsigned int mant_bits, mant_off; | |
| 394 int mant_bits_left; | |
| 395 | |
| 396 mant_off = fmt->man_start; | |
| 397 mant_bits_left = fmt->man_len; | |
| 398 while (mant_bits_left > 0) | |
| 399 { | |
| 400 mant_bits = min (mant_bits_left, 32); | |
| 401 | |
| 402 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, | |
| 403 mant_off, mant_bits) != 0) | |
| 404 return 1; | |
| 405 | |
| 406 mant_off += mant_bits; | |
| 407 mant_bits_left -= mant_bits; | |
| 408 } | |
| 409 return 0; | |
| 410 } | |
| 411 | |
| 412 /* Extract a field which starts at START and is LEN bits long. DATA and | |
| 413 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ | |
| 414 static unsigned long | |
| 415 get_field (const unsigned char *data, enum floatformat_byteorders order, | |
| 416 unsigned int total_len, unsigned int start, unsigned int len) | |
| 417 { | |
| 418 unsigned long result = 0; | |
| 419 unsigned int cur_byte; | |
| 420 int lo_bit, hi_bit, cur_bitshift = 0; | |
| 421 int nextbyte = (order == floatformat_little) ? 1 : -1; | |
| 422 | |
| 423 /* Start is in big-endian bit order! Fix that first. */ | |
| 424 start = total_len - (start + len); | |
| 425 | |
| 426 /* Start at the least significant part of the field. */ | |
| 427 if (order == floatformat_little) | |
| 428 cur_byte = start / FLOATFORMAT_CHAR_BIT; | |
| 429 else | |
| 430 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; | |
| 431 | |
| 432 lo_bit = start % FLOATFORMAT_CHAR_BIT; | |
| 433 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); | |
| 434 | |
| 435 do | |
| 436 { | |
| 437 unsigned int shifted = *(data + cur_byte) >> lo_bit; | |
| 438 unsigned int bits = hi_bit - lo_bit; | |
| 439 unsigned int mask = (1 << bits) - 1; | |
| 440 result |= (shifted & mask) << cur_bitshift; | |
| 441 len -= bits; | |
| 442 cur_bitshift += bits; | |
| 443 cur_byte += nextbyte; | |
| 444 lo_bit = 0; | |
| 445 hi_bit = min (len, FLOATFORMAT_CHAR_BIT); | |
| 446 } | |
| 447 while (len != 0); | |
| 448 | |
| 449 return result; | |
| 450 } | |
| 451 | |
| 452 /* Convert from FMT to a double. | |
| 453 FROM is the address of the extended float. | |
| 454 Store the double in *TO. */ | |
| 455 | |
| 456 void | |
| 457 floatformat_to_double (const struct floatformat *fmt, | |
| 458 const void *from, double *to) | |
| 459 { | |
| 460 const unsigned char *ufrom = (const unsigned char *) from; | |
| 461 double dto; | |
| 462 long exponent; | |
| 463 unsigned long mant; | |
| 464 unsigned int mant_bits, mant_off; | |
| 465 int mant_bits_left; | |
| 466 int special_exponent; /* It's a NaN, denorm or zero */ | |
| 467 | |
| 468 /* Split values are not handled specially, since the top half has | |
| 469 the correctly rounded double value (in the only supported case of | |
| 470 split values). */ | |
| 471 | |
| 472 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, | |
| 473 fmt->exp_start, fmt->exp_len); | |
| 474 | |
| 475 /* If the exponent indicates a NaN, we don't have information to | |
| 476 decide what to do. So we handle it like IEEE, except that we | |
| 477 don't try to preserve the type of NaN. FIXME. */ | |
| 478 if ((unsigned long) exponent == fmt->exp_nan) | |
| 479 { | |
| 480 int nan = mant_bits_set (fmt, ufrom); | |
| 481 | |
| 482 /* On certain systems (such as GNU/Linux), the use of the | |
| 483 INFINITY macro below may generate a warning that can not be | |
| 484 silenced due to a bug in GCC (PR preprocessor/11931). The | |
| 485 preprocessor fails to recognise the __extension__ keyword in | |
| 486 conjunction with the GNU/C99 extension for hexadecimal | |
| 487 floating point constants and will issue a warning when | |
| 488 compiling with -pedantic. */ | |
| 489 if (nan) | |
| 490 dto = NAN; | |
| 491 else | |
| 492 dto = INFINITY; | |
| 493 | |
| 494 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) | |
| 495 dto = -dto; | |
| 496 | |
| 497 *to = dto; | |
| 498 | |
| 499 return; | |
| 500 } | |
| 501 | |
| 502 mant_bits_left = fmt->man_len; | |
| 503 mant_off = fmt->man_start; | |
| 504 dto = 0.0; | |
| 505 | |
| 506 special_exponent = exponent == 0 || (unsigned long) exponent == fmt->exp_nan; | |
| 507 | |
| 508 /* Don't bias zero's, denorms or NaNs. */ | |
| 509 if (!special_exponent) | |
| 510 exponent -= fmt->exp_bias; | |
| 511 | |
| 512 /* Build the result algebraically. Might go infinite, underflow, etc; | |
| 513 who cares. */ | |
| 514 | |
| 515 /* If this format uses a hidden bit, explicitly add it in now. Otherwise, | |
| 516 increment the exponent by one to account for the integer bit. */ | |
| 517 | |
| 518 if (!special_exponent) | |
| 519 { | |
| 520 if (fmt->intbit == floatformat_intbit_no) | |
| 521 dto = ldexp (1.0, exponent); | |
| 522 else | |
| 523 exponent++; | |
| 524 } | |
| 525 | |
| 526 while (mant_bits_left > 0) | |
| 527 { | |
| 528 mant_bits = min (mant_bits_left, 32); | |
| 529 | |
| 530 mant = get_field (ufrom, fmt->byteorder, fmt->totalsize, | |
| 531 mant_off, mant_bits); | |
| 532 | |
| 533 /* Handle denormalized numbers. FIXME: What should we do for | |
| 534 non-IEEE formats? */ | |
| 535 if (special_exponent && exponent == 0 && mant != 0) | |
| 536 dto += ldexp ((double)mant, | |
| 537 (- fmt->exp_bias | |
| 538 - mant_bits | |
| 539 - (mant_off - fmt->man_start) | |
| 540 + 1)); | |
| 541 else | |
| 542 dto += ldexp ((double)mant, exponent - mant_bits); | |
| 543 if (exponent != 0) | |
| 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 <stdio.h> | |
| 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 (256.0); | |
| 760 ieee_test (0.12345); | |
| 761 ieee_test (234235.78907234); | |
| 762 ieee_test (-512.0); | |
| 763 ieee_test (-0.004321); | |
| 764 ieee_test (1.2E-70); | |
| 765 ieee_test (1.2E-316); | |
| 766 ieee_test (4.9406564584124654E-324); | |
| 767 ieee_test (- 4.9406564584124654E-324); | |
| 768 ieee_test (- 0.0); | |
| 769 ieee_test (- INFINITY); | |
| 770 ieee_test (- NAN); | |
| 771 ieee_test (INFINITY); | |
| 772 ieee_test (NAN); | |
| 773 return 0; | |
| 774 } | |
| 775 #endif |