floatformat.c revision 1.7
1/* IEEE floating point support routines, for GDB, the GNU Debugger. 2 Copyright (C) 1991-2020 Free Software Foundation, Inc. 3 4This file is part of GDB. 5 6This program is free software; you can redistribute it and/or modify 7it under the terms of the GNU General Public License as published by 8the Free Software Foundation; either version 2 of the License, or 9(at your option) any later version. 10 11This program is distributed in the hope that it will be useful, 12but WITHOUT ANY WARRANTY; without even the implied warranty of 13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14GNU General Public License for more details. 15 16You should have received a copy of the GNU General Public License 17along with this program; if not, write to the Free Software 18Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA. */ 19 20/* This is needed to pick up the NAN macro on some systems. */ 21#ifndef _GNU_SOURCE 22#define _GNU_SOURCE 23#endif 24 25#ifdef HAVE_CONFIG_H 26#include "config.h" 27#endif 28 29#include <math.h> 30 31#ifdef HAVE_STRING_H 32#include <string.h> 33#endif 34 35/* On some platforms, <float.h> provides DBL_QNAN. */ 36#ifdef STDC_HEADERS 37#include <float.h> 38#endif 39 40#include "ansidecl.h" 41#include "libiberty.h" 42#include "floatformat.h" 43 44#ifndef INFINITY 45#ifdef HUGE_VAL 46#define INFINITY HUGE_VAL 47#else 48#define INFINITY (1.0 / 0.0) 49#endif 50#endif 51 52#ifndef NAN 53#ifdef DBL_QNAN 54#define NAN DBL_QNAN 55#else 56#define NAN (0.0 / 0.0) 57#endif 58#endif 59 60static int mant_bits_set (const struct floatformat *, const unsigned char *); 61static unsigned long get_field (const unsigned char *, 62 enum floatformat_byteorders, 63 unsigned int, 64 unsigned int, 65 unsigned int); 66static int floatformat_always_valid (const struct floatformat *fmt, 67 const void *from); 68 69static int 70floatformat_always_valid (const struct floatformat *fmt ATTRIBUTE_UNUSED, 71 const void *from ATTRIBUTE_UNUSED) 72{ 73 return 1; 74} 75 76/* The odds that CHAR_BIT will be anything but 8 are low enough that I'm not 77 going to bother with trying to muck around with whether it is defined in 78 a system header, what we do if not, etc. */ 79#define FLOATFORMAT_CHAR_BIT 8 80 81/* floatformats for IEEE half, single and double, big and little endian. */ 82const struct floatformat floatformat_ieee_half_big = 83{ 84 floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10, 85 floatformat_intbit_no, 86 "floatformat_ieee_half_big", 87 floatformat_always_valid, 88 NULL 89}; 90const struct floatformat floatformat_ieee_half_little = 91{ 92 floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10, 93 floatformat_intbit_no, 94 "floatformat_ieee_half_little", 95 floatformat_always_valid, 96 NULL 97}; 98const struct floatformat floatformat_ieee_single_big = 99{ 100 floatformat_big, 32, 0, 1, 8, 127, 255, 9, 23, 101 floatformat_intbit_no, 102 "floatformat_ieee_single_big", 103 floatformat_always_valid, 104 NULL 105}; 106const struct floatformat floatformat_ieee_single_little = 107{ 108 floatformat_little, 32, 0, 1, 8, 127, 255, 9, 23, 109 floatformat_intbit_no, 110 "floatformat_ieee_single_little", 111 floatformat_always_valid, 112 NULL 113}; 114const struct floatformat floatformat_ieee_double_big = 115{ 116 floatformat_big, 64, 0, 1, 11, 1023, 2047, 12, 52, 117 floatformat_intbit_no, 118 "floatformat_ieee_double_big", 119 floatformat_always_valid, 120 NULL 121}; 122const struct floatformat floatformat_ieee_double_little = 123{ 124 floatformat_little, 64, 0, 1, 11, 1023, 2047, 12, 52, 125 floatformat_intbit_no, 126 "floatformat_ieee_double_little", 127 floatformat_always_valid, 128 NULL 129}; 130 131/* floatformat for IEEE double, little endian byte order, with big endian word 132 ordering, as on the ARM. */ 133 134const struct floatformat floatformat_ieee_double_littlebyte_bigword = 135{ 136 floatformat_littlebyte_bigword, 64, 0, 1, 11, 1023, 2047, 12, 52, 137 floatformat_intbit_no, 138 "floatformat_ieee_double_littlebyte_bigword", 139 floatformat_always_valid, 140 NULL 141}; 142 143/* floatformat for VAX. Not quite IEEE, but close enough. */ 144 145const struct floatformat floatformat_vax_f = 146{ 147 floatformat_vax, 32, 0, 1, 8, 129, 0, 9, 23, 148 floatformat_intbit_no, 149 "floatformat_vax_f", 150 floatformat_always_valid, 151 NULL 152}; 153const struct floatformat floatformat_vax_d = 154{ 155 floatformat_vax, 64, 0, 1, 8, 129, 0, 9, 55, 156 floatformat_intbit_no, 157 "floatformat_vax_d", 158 floatformat_always_valid, 159 NULL 160}; 161const struct floatformat floatformat_vax_g = 162{ 163 floatformat_vax, 64, 0, 1, 11, 1025, 0, 12, 52, 164 floatformat_intbit_no, 165 "floatformat_vax_g", 166 floatformat_always_valid, 167 NULL 168}; 169 170static int floatformat_i387_ext_is_valid (const struct floatformat *fmt, 171 const void *from); 172 173static int 174floatformat_i387_ext_is_valid (const struct floatformat *fmt, const void *from) 175{ 176 /* In the i387 double-extended format, if the exponent is all ones, 177 then the integer bit must be set. If the exponent is neither 0 178 nor ~0, the intbit must also be set. Only if the exponent is 179 zero can it be zero, and then it must be zero. */ 180 unsigned long exponent, int_bit; 181 const unsigned char *ufrom = (const unsigned char *) from; 182 183 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, 184 fmt->exp_start, fmt->exp_len); 185 int_bit = get_field (ufrom, fmt->byteorder, fmt->totalsize, 186 fmt->man_start, 1); 187 188 if ((exponent == 0) != (int_bit == 0)) 189 return 0; 190 else 191 return 1; 192} 193 194const struct floatformat floatformat_i387_ext = 195{ 196 floatformat_little, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64, 197 floatformat_intbit_yes, 198 "floatformat_i387_ext", 199 floatformat_i387_ext_is_valid, 200 NULL 201}; 202const struct floatformat floatformat_m68881_ext = 203{ 204 /* Note that the bits from 16 to 31 are unused. */ 205 floatformat_big, 96, 0, 1, 15, 0x3fff, 0x7fff, 32, 64, 206 floatformat_intbit_yes, 207 "floatformat_m68881_ext", 208 floatformat_always_valid, 209 NULL 210}; 211const struct floatformat floatformat_i960_ext = 212{ 213 /* Note that the bits from 0 to 15 are unused. */ 214 floatformat_little, 96, 16, 17, 15, 0x3fff, 0x7fff, 32, 64, 215 floatformat_intbit_yes, 216 "floatformat_i960_ext", 217 floatformat_always_valid, 218 NULL 219}; 220const struct floatformat floatformat_m88110_ext = 221{ 222 floatformat_big, 80, 0, 1, 15, 0x3fff, 0x7fff, 16, 64, 223 floatformat_intbit_yes, 224 "floatformat_m88110_ext", 225 floatformat_always_valid, 226 NULL 227}; 228const struct floatformat floatformat_m88110_harris_ext = 229{ 230 /* Harris uses raw format 128 bytes long, but the number is just an ieee 231 double, and the last 64 bits are wasted. */ 232 floatformat_big,128, 0, 1, 11, 0x3ff, 0x7ff, 12, 52, 233 floatformat_intbit_no, 234 "floatformat_m88110_ext_harris", 235 floatformat_always_valid, 236 NULL 237}; 238const struct floatformat floatformat_arm_ext_big = 239{ 240 /* Bits 1 to 16 are unused. */ 241 floatformat_big, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64, 242 floatformat_intbit_yes, 243 "floatformat_arm_ext_big", 244 floatformat_always_valid, 245 NULL 246}; 247const struct floatformat floatformat_arm_ext_littlebyte_bigword = 248{ 249 /* Bits 1 to 16 are unused. */ 250 floatformat_littlebyte_bigword, 96, 0, 17, 15, 0x3fff, 0x7fff, 32, 64, 251 floatformat_intbit_yes, 252 "floatformat_arm_ext_littlebyte_bigword", 253 floatformat_always_valid, 254 NULL 255}; 256const struct floatformat floatformat_ia64_spill_big = 257{ 258 floatformat_big, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64, 259 floatformat_intbit_yes, 260 "floatformat_ia64_spill_big", 261 floatformat_always_valid, 262 NULL 263}; 264const struct floatformat floatformat_ia64_spill_little = 265{ 266 floatformat_little, 128, 0, 1, 17, 65535, 0x1ffff, 18, 64, 267 floatformat_intbit_yes, 268 "floatformat_ia64_spill_little", 269 floatformat_always_valid, 270 NULL 271}; 272const struct floatformat floatformat_ia64_quad_big = 273{ 274 floatformat_big, 128, 0, 1, 15, 16383, 0x7fff, 16, 112, 275 floatformat_intbit_no, 276 "floatformat_ia64_quad_big", 277 floatformat_always_valid, 278 NULL 279}; 280const struct floatformat floatformat_ia64_quad_little = 281{ 282 floatformat_little, 128, 0, 1, 15, 16383, 0x7fff, 16, 112, 283 floatformat_intbit_no, 284 "floatformat_ia64_quad_little", 285 floatformat_always_valid, 286 NULL 287}; 288 289static int 290floatformat_ibm_long_double_is_valid (const struct floatformat *fmt, 291 const void *from) 292{ 293 const unsigned char *ufrom = (const unsigned char *) from; 294 const struct floatformat *hfmt = fmt->split_half; 295 long top_exp, bot_exp; 296 int top_nan = 0; 297 298 top_exp = get_field (ufrom, hfmt->byteorder, hfmt->totalsize, 299 hfmt->exp_start, hfmt->exp_len); 300 bot_exp = get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize, 301 hfmt->exp_start, hfmt->exp_len); 302 303 if ((unsigned long) top_exp == hfmt->exp_nan) 304 top_nan = mant_bits_set (hfmt, ufrom); 305 306 /* A NaN is valid with any low part. */ 307 if (top_nan) 308 return 1; 309 310 /* An infinity, zero or denormal requires low part 0 (positive or 311 negative). */ 312 if ((unsigned long) top_exp == hfmt->exp_nan || top_exp == 0) 313 { 314 if (bot_exp != 0) 315 return 0; 316 317 return !mant_bits_set (hfmt, ufrom + 8); 318 } 319 320 /* The top part is now a finite normal value. The long double value 321 is the sum of the two parts, and the top part must equal the 322 result of rounding the long double value to nearest double. Thus 323 the bottom part must be <= 0.5ulp of the top part in absolute 324 value, and if it is < 0.5ulp then the long double is definitely 325 valid. */ 326 if (bot_exp < top_exp - 53) 327 return 1; 328 if (bot_exp > top_exp - 53 && bot_exp != 0) 329 return 0; 330 if (bot_exp == 0) 331 { 332 /* The bottom part is 0 or denormal. Determine which, and if 333 denormal the first two set bits. */ 334 int first_bit = -1, second_bit = -1, cur_bit; 335 for (cur_bit = 0; (unsigned int) cur_bit < hfmt->man_len; cur_bit++) 336 if (get_field (ufrom + 8, hfmt->byteorder, hfmt->totalsize, 337 hfmt->man_start + cur_bit, 1)) 338 { 339 if (first_bit == -1) 340 first_bit = cur_bit; 341 else 342 { 343 second_bit = cur_bit; 344 break; 345 } 346 } 347 /* Bottom part 0 is OK. */ 348 if (first_bit == -1) 349 return 1; 350 /* The real exponent of the bottom part is -first_bit. */ 351 if (-first_bit < top_exp - 53) 352 return 1; 353 if (-first_bit > top_exp - 53) 354 return 0; 355 /* The bottom part is at least 0.5ulp of the top part. For this 356 to be OK, the bottom part must be exactly 0.5ulp (i.e. no 357 more bits set) and the top part must have last bit 0. */ 358 if (second_bit != -1) 359 return 0; 360 return !get_field (ufrom, hfmt->byteorder, hfmt->totalsize, 361 hfmt->man_start + hfmt->man_len - 1, 1); 362 } 363 else 364 { 365 /* The bottom part is at least 0.5ulp of the top part. For this 366 to be OK, it must be exactly 0.5ulp (i.e. no explicit bits 367 set) and the top part must have last bit 0. */ 368 if (get_field (ufrom, hfmt->byteorder, hfmt->totalsize, 369 hfmt->man_start + hfmt->man_len - 1, 1)) 370 return 0; 371 return !mant_bits_set (hfmt, ufrom + 8); 372 } 373} 374 375const struct floatformat floatformat_ibm_long_double_big = 376{ 377 floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52, 378 floatformat_intbit_no, 379 "floatformat_ibm_long_double_big", 380 floatformat_ibm_long_double_is_valid, 381 &floatformat_ieee_double_big 382}; 383 384const struct floatformat floatformat_ibm_long_double_little = 385{ 386 floatformat_little, 128, 0, 1, 11, 1023, 2047, 12, 52, 387 floatformat_intbit_no, 388 "floatformat_ibm_long_double_little", 389 floatformat_ibm_long_double_is_valid, 390 &floatformat_ieee_double_little 391}; 392 393 394#ifndef min 395#define min(a, b) ((a) < (b) ? (a) : (b)) 396#endif 397 398/* Return 1 if any bits are explicitly set in the mantissa of UFROM, 399 format FMT, 0 otherwise. */ 400static int 401mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom) 402{ 403 unsigned int mant_bits, mant_off; 404 int mant_bits_left; 405 406 mant_off = fmt->man_start; 407 mant_bits_left = fmt->man_len; 408 while (mant_bits_left > 0) 409 { 410 mant_bits = min (mant_bits_left, 32); 411 412 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, 413 mant_off, mant_bits) != 0) 414 return 1; 415 416 mant_off += mant_bits; 417 mant_bits_left -= mant_bits; 418 } 419 return 0; 420} 421 422/* Extract a field which starts at START and is LEN bits long. DATA and 423 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ 424static unsigned long 425get_field (const unsigned char *data, enum floatformat_byteorders order, 426 unsigned int total_len, unsigned int start, unsigned int len) 427{ 428 unsigned long result = 0; 429 unsigned int cur_byte; 430 int lo_bit, hi_bit, cur_bitshift = 0; 431 int nextbyte = (order == floatformat_little) ? 1 : -1; 432 433 /* Start is in big-endian bit order! Fix that first. */ 434 start = total_len - (start + len); 435 436 /* Start at the least significant part of the field. */ 437 if (order == floatformat_little) 438 cur_byte = start / FLOATFORMAT_CHAR_BIT; 439 else 440 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; 441 442 lo_bit = start % FLOATFORMAT_CHAR_BIT; 443 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); 444 445 do 446 { 447 unsigned int shifted = *(data + cur_byte) >> lo_bit; 448 unsigned int bits = hi_bit - lo_bit; 449 unsigned int mask = (1 << bits) - 1; 450 result |= (shifted & mask) << cur_bitshift; 451 len -= bits; 452 cur_bitshift += bits; 453 cur_byte += nextbyte; 454 lo_bit = 0; 455 hi_bit = min (len, FLOATFORMAT_CHAR_BIT); 456 } 457 while (len != 0); 458 459 return result; 460} 461 462/* Convert from FMT to a double. 463 FROM is the address of the extended float. 464 Store the double in *TO. */ 465 466void 467floatformat_to_double (const struct floatformat *fmt, 468 const void *from, double *to) 469{ 470 const unsigned char *ufrom = (const unsigned char *) from; 471 double dto; 472 long exponent; 473 unsigned long mant; 474 unsigned int mant_bits, mant_off; 475 int mant_bits_left; 476 477 /* Split values are not handled specially, since the top half has 478 the correctly rounded double value (in the only supported case of 479 split values). */ 480 481 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, 482 fmt->exp_start, fmt->exp_len); 483 484 /* If the exponent indicates a NaN, we don't have information to 485 decide what to do. So we handle it like IEEE, except that we 486 don't try to preserve the type of NaN. FIXME. */ 487 if ((unsigned long) exponent == fmt->exp_nan) 488 { 489 int nan = mant_bits_set (fmt, ufrom); 490 491 /* On certain systems (such as GNU/Linux), the use of the 492 INFINITY macro below may generate a warning that cannot be 493 silenced due to a bug in GCC (PR preprocessor/11931). The 494 preprocessor fails to recognise the __extension__ keyword in 495 conjunction with the GNU/C99 extension for hexadecimal 496 floating point constants and will issue a warning when 497 compiling with -pedantic. */ 498 if (nan) 499 dto = NAN; 500 else 501#ifdef __vax__ 502 dto = HUGE_VAL; 503#else 504 dto = INFINITY; 505#endif 506 507 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) 508 dto = -dto; 509 510 *to = dto; 511 512 return; 513 } 514 515 mant_bits_left = fmt->man_len; 516 mant_off = fmt->man_start; 517 dto = 0.0; 518 519 /* Build the result algebraically. Might go infinite, underflow, etc; 520 who cares. */ 521 522 /* For denorms use minimum exponent. */ 523 if (exponent == 0) 524 exponent = 1 - fmt->exp_bias; 525 else 526 { 527 exponent -= fmt->exp_bias; 528 529 /* If this format uses a hidden bit, explicitly add it in now. 530 Otherwise, increment the exponent by one to account for the 531 integer bit. */ 532 533 if (fmt->intbit == floatformat_intbit_no) 534 dto = ldexp (1.0, exponent); 535 else 536 exponent++; 537 } 538 539 while (mant_bits_left > 0) 540 { 541 mant_bits = min (mant_bits_left, 32); 542 543 mant = get_field (ufrom, fmt->byteorder, fmt->totalsize, 544 mant_off, mant_bits); 545 546 dto += ldexp ((double) mant, exponent - mant_bits); 547 exponent -= mant_bits; 548 mant_off += mant_bits; 549 mant_bits_left -= mant_bits; 550 } 551 552 /* Negate it if negative. */ 553 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) 554 dto = -dto; 555 *to = dto; 556} 557 558static void put_field (unsigned char *, enum floatformat_byteorders, 559 unsigned int, 560 unsigned int, 561 unsigned int, 562 unsigned long); 563 564/* Set a field which starts at START and is LEN bits long. DATA and 565 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ 566static void 567put_field (unsigned char *data, enum floatformat_byteorders order, 568 unsigned int total_len, unsigned int start, unsigned int len, 569 unsigned long stuff_to_put) 570{ 571 unsigned int cur_byte; 572 int lo_bit, hi_bit; 573 int nextbyte = (order == floatformat_little) ? 1 : -1; 574 575 /* Start is in big-endian bit order! Fix that first. */ 576 start = total_len - (start + len); 577 578 /* Start at the least significant part of the field. */ 579 if (order == floatformat_little) 580 cur_byte = start / FLOATFORMAT_CHAR_BIT; 581 else 582 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; 583 584 lo_bit = start % FLOATFORMAT_CHAR_BIT; 585 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); 586 587 do 588 { 589 unsigned char *byte_ptr = data + cur_byte; 590 unsigned int bits = hi_bit - lo_bit; 591 unsigned int mask = ((1 << bits) - 1) << lo_bit; 592 *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask); 593 stuff_to_put >>= bits; 594 len -= bits; 595 cur_byte += nextbyte; 596 lo_bit = 0; 597 hi_bit = min (len, FLOATFORMAT_CHAR_BIT); 598 } 599 while (len != 0); 600} 601 602/* The converse: convert the double *FROM to an extended float 603 and store where TO points. Neither FROM nor TO have any alignment 604 restrictions. */ 605 606void 607floatformat_from_double (const struct floatformat *fmt, 608 const double *from, void *to) 609{ 610 double dfrom; 611 int exponent; 612 double mant; 613 unsigned int mant_bits, mant_off; 614 int mant_bits_left; 615 unsigned char *uto = (unsigned char *) to; 616 617 dfrom = *from; 618 memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT); 619 620 /* Split values are not handled specially, since a bottom half of 621 zero is correct for any value representable as double (in the 622 only supported case of split values). */ 623 624 /* If negative, set the sign bit. */ 625 if (dfrom < 0) 626 { 627 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1); 628 dfrom = -dfrom; 629 } 630 631 if (dfrom == 0) 632 { 633 /* 0.0. */ 634 return; 635 } 636 637 if (dfrom != dfrom) 638 { 639 /* NaN. */ 640 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 641 fmt->exp_len, fmt->exp_nan); 642 /* Be sure it's not infinity, but NaN value is irrelevant. */ 643 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start, 644 32, 1); 645 return; 646 } 647 648 if (dfrom + dfrom == dfrom) 649 { 650 /* This can only happen for an infinite value (or zero, which we 651 already handled above). */ 652 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 653 fmt->exp_len, fmt->exp_nan); 654 return; 655 } 656 657 mant = frexp (dfrom, &exponent); 658 if (exponent + fmt->exp_bias - 1 > 0) 659 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 660 fmt->exp_len, exponent + fmt->exp_bias - 1); 661 else 662 { 663 /* Handle a denormalized number. FIXME: What should we do for 664 non-IEEE formats? */ 665 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 666 fmt->exp_len, 0); 667 mant = ldexp (mant, exponent + fmt->exp_bias - 1); 668 } 669 670 mant_bits_left = fmt->man_len; 671 mant_off = fmt->man_start; 672 while (mant_bits_left > 0) 673 { 674 unsigned long mant_long; 675 mant_bits = mant_bits_left < 32 ? mant_bits_left : 32; 676 677 mant *= 4294967296.0; 678 mant_long = (unsigned long)mant; 679 mant -= mant_long; 680 681 /* If the integer bit is implicit, and we are not creating a 682 denormalized number, then we need to discard it. */ 683 if ((unsigned int) mant_bits_left == fmt->man_len 684 && fmt->intbit == floatformat_intbit_no 685 && exponent + fmt->exp_bias - 1 > 0) 686 { 687 mant_long &= 0x7fffffff; 688 mant_bits -= 1; 689 } 690 else if (mant_bits < 32) 691 { 692 /* The bits we want are in the most significant MANT_BITS bits of 693 mant_long. Move them to the least significant. */ 694 mant_long >>= 32 - mant_bits; 695 } 696 697 put_field (uto, fmt->byteorder, fmt->totalsize, 698 mant_off, mant_bits, mant_long); 699 mant_off += mant_bits; 700 mant_bits_left -= mant_bits; 701 } 702} 703 704/* Return non-zero iff the data at FROM is a valid number in format FMT. */ 705 706int 707floatformat_is_valid (const struct floatformat *fmt, const void *from) 708{ 709 return fmt->is_valid (fmt, from); 710} 711 712 713#ifdef IEEE_DEBUG 714 715#include <stdio.h> 716 717/* This is to be run on a host which uses IEEE floating point. */ 718 719void 720ieee_test (double n) 721{ 722 double result; 723 724 floatformat_to_double (&floatformat_ieee_double_little, &n, &result); 725 if ((n != result && (! isnan (n) || ! isnan (result))) 726 || (n < 0 && result >= 0) 727 || (n >= 0 && result < 0)) 728 printf ("Differ(to): %.20g -> %.20g\n", n, result); 729 730 floatformat_from_double (&floatformat_ieee_double_little, &n, &result); 731 if ((n != result && (! isnan (n) || ! isnan (result))) 732 || (n < 0 && result >= 0) 733 || (n >= 0 && result < 0)) 734 printf ("Differ(from): %.20g -> %.20g\n", n, result); 735 736#if 0 737 { 738 char exten[16]; 739 740 floatformat_from_double (&floatformat_m68881_ext, &n, exten); 741 floatformat_to_double (&floatformat_m68881_ext, exten, &result); 742 if (n != result) 743 printf ("Differ(to+from): %.20g -> %.20g\n", n, result); 744 } 745#endif 746 747#if IEEE_DEBUG > 1 748 /* This is to be run on a host which uses 68881 format. */ 749 { 750 long double ex = *(long double *)exten; 751 if (ex != n) 752 printf ("Differ(from vs. extended): %.20g\n", n); 753 } 754#endif 755} 756 757int 758main (void) 759{ 760 ieee_test (0.0); 761 ieee_test (0.5); 762 ieee_test (1.1); 763 ieee_test (256.0); 764 ieee_test (0.12345); 765 ieee_test (234235.78907234); 766 ieee_test (-512.0); 767 ieee_test (-0.004321); 768 ieee_test (1.2E-70); 769 ieee_test (1.2E-316); 770 ieee_test (4.9406564584124654E-324); 771 ieee_test (- 4.9406564584124654E-324); 772 ieee_test (- 0.0); 773 ieee_test (- INFINITY); 774 ieee_test (- NAN); 775 ieee_test (INFINITY); 776 ieee_test (NAN); 777 return 0; 778} 779#endif 780