1/* IEEE floating point support routines, for GDB, the GNU Debugger. 2 Copyright 1991, 1994, 1999, 2000, 2003, 2005, 2006, 2010, 2012 3 Free Software Foundation, Inc. 4 5This file is part of GDB. 6 7This program is free software; you can redistribute it and/or modify 8it under the terms of the GNU General Public License as published by 9the Free Software Foundation; either version 2 of the License, or 10(at your option) any later version. 11 12This program is distributed in the hope that it will be useful, 13but WITHOUT ANY WARRANTY; without even the implied warranty of 14MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15GNU General Public License for more details. 16 17You should have received a copy of the GNU General Public License 18along with this program; if not, write to the Free Software 19Foundation, 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 59static int mant_bits_set (const struct floatformat *, const unsigned char *); 60static unsigned long get_field (const unsigned char *, 61 enum floatformat_byteorders, 62 unsigned int, 63 unsigned int, 64 unsigned int); 65static int floatformat_always_valid (const struct floatformat *fmt, 66 const void *from); 67 68static int 69floatformat_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 80/* floatformats for IEEE half, single and double, big and little endian. */ 81const struct floatformat floatformat_ieee_half_big = 82{ 83 floatformat_big, 16, 0, 1, 5, 15, 31, 6, 10, 84 floatformat_intbit_no, 85 "floatformat_ieee_half_big", 86 floatformat_always_valid, 87 NULL 88}; 89const struct floatformat floatformat_ieee_half_little = 90{ 91 floatformat_little, 16, 0, 1, 5, 15, 31, 6, 10, 92 floatformat_intbit_no, 93 "floatformat_ieee_half_little", 94 floatformat_always_valid, 95 NULL 96}; 97const 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}; 105const 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}; 113const 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}; 121const 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 133const 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 144const 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}; 152const 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}; 160const 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 169static int floatformat_i387_ext_is_valid (const struct floatformat *fmt, 170 const void *from); 171 172static int 173floatformat_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 193const 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}; 201const 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}; 210const 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}; 219const 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}; 227const 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}; 237const 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}; 246const 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}; 255const 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}; 263const 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}; 271const 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}; 279const 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 288static int 289floatformat_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 374const struct floatformat floatformat_ibm_long_double_big = 375{ 376 floatformat_big, 128, 0, 1, 11, 1023, 2047, 12, 52, 377 floatformat_intbit_no, 378 "floatformat_ibm_long_double_big", 379 floatformat_ibm_long_double_is_valid, 380 &floatformat_ieee_double_big 381}; 382 383const struct floatformat floatformat_ibm_long_double_little = 384{ 385 floatformat_little, 128, 0, 1, 11, 1023, 2047, 12, 52, 386 floatformat_intbit_no, 387 "floatformat_ibm_long_double_little", 388 floatformat_ibm_long_double_is_valid, 389 &floatformat_ieee_double_little 390}; 391 392 393#ifndef min 394#define min(a, b) ((a) < (b) ? (a) : (b)) 395#endif 396 397/* Return 1 if any bits are explicitly set in the mantissa of UFROM, 398 format FMT, 0 otherwise. */ 399static int 400mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom) 401{ 402 unsigned int mant_bits, mant_off; 403 int mant_bits_left; 404 405 mant_off = fmt->man_start; 406 mant_bits_left = fmt->man_len; 407 while (mant_bits_left > 0) 408 { 409 mant_bits = min (mant_bits_left, 32); 410 411 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, 412 mant_off, mant_bits) != 0) 413 return 1; 414 415 mant_off += mant_bits; 416 mant_bits_left -= mant_bits; 417 } 418 return 0; 419} 420 421/* Extract a field which starts at START and is LEN bits long. DATA and 422 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ 423static unsigned long 424get_field (const unsigned char *data, enum floatformat_byteorders order, 425 unsigned int total_len, unsigned int start, unsigned int len) 426{ 427 unsigned long result = 0; 428 unsigned int cur_byte; 429 int lo_bit, hi_bit, cur_bitshift = 0; 430 int nextbyte = (order == floatformat_little) ? 1 : -1; 431 432 /* Start is in big-endian bit order! Fix that first. */ 433 start = total_len - (start + len); 434 435 /* Start at the least significant part of the field. */ 436 if (order == floatformat_little) 437 cur_byte = start / FLOATFORMAT_CHAR_BIT; 438 else 439 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; 440 441 lo_bit = start % FLOATFORMAT_CHAR_BIT; 442 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); 443 444 do 445 { 446 unsigned int shifted = *(data + cur_byte) >> lo_bit; 447 unsigned int bits = hi_bit - lo_bit; 448 unsigned int mask = (1 << bits) - 1; 449 result |= (shifted & mask) << cur_bitshift; 450 len -= bits; 451 cur_bitshift += bits; 452 cur_byte += nextbyte; 453 lo_bit = 0; 454 hi_bit = min (len, FLOATFORMAT_CHAR_BIT); 455 } 456 while (len != 0); 457 458 return result; 459} 460 461/* Convert from FMT to a double. 462 FROM is the address of the extended float. 463 Store the double in *TO. */ 464 465void 466floatformat_to_double (const struct floatformat *fmt, 467 const void *from, double *to) 468{ 469 const unsigned char *ufrom = (const unsigned char *) from; 470 double dto; 471 long exponent; 472 unsigned long mant; 473 unsigned int mant_bits, mant_off; 474 int mant_bits_left; 475 476 /* Split values are not handled specially, since the top half has 477 the correctly rounded double value (in the only supported case of 478 split values). */ 479 480 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, 481 fmt->exp_start, fmt->exp_len); 482 483 /* If the exponent indicates a NaN, we don't have information to 484 decide what to do. So we handle it like IEEE, except that we 485 don't try to preserve the type of NaN. FIXME. */ 486 if ((unsigned long) exponent == fmt->exp_nan) 487 { 488 int nan = mant_bits_set (fmt, ufrom); 489 490 /* On certain systems (such as GNU/Linux), the use of the 491 INFINITY macro below may generate a warning that can not be 492 silenced due to a bug in GCC (PR preprocessor/11931). The 493 preprocessor fails to recognise the __extension__ keyword in 494 conjunction with the GNU/C99 extension for hexadecimal 495 floating point constants and will issue a warning when 496 compiling with -pedantic. */ 497 if (nan) 498 dto = NAN; 499 else 500 dto = INFINITY; 501 502 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) 503 dto = -dto; 504 505 *to = dto; 506 507 return; 508 } 509 510 mant_bits_left = fmt->man_len; 511 mant_off = fmt->man_start; 512 dto = 0.0; 513 514 /* Build the result algebraically. Might go infinite, underflow, etc; 515 who cares. */ 516 517 /* For denorms use minimum exponent. */ 518 if (exponent == 0) 519 exponent = 1 - fmt->exp_bias; 520 else 521 { 522 exponent -= fmt->exp_bias; 523 524 /* If this format uses a hidden bit, explicitly add it in now. 525 Otherwise, increment the exponent by one to account for the 526 integer bit. */ 527 528 if (fmt->intbit == floatformat_intbit_no) 529 dto = ldexp (1.0, exponent); 530 else 531 exponent++; 532 } 533 534 while (mant_bits_left > 0) 535 { 536 mant_bits = min (mant_bits_left, 32); 537 538 mant = get_field (ufrom, fmt->byteorder, fmt->totalsize, 539 mant_off, mant_bits); 540 541 dto += ldexp ((double) mant, exponent - mant_bits); 542 exponent -= mant_bits; 543 mant_off += mant_bits; 544 mant_bits_left -= mant_bits; 545 } 546 547 /* Negate it if negative. */ 548 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) 549 dto = -dto; 550 *to = dto; 551} 552 553static void put_field (unsigned char *, enum floatformat_byteorders, 554 unsigned int, 555 unsigned int, 556 unsigned int, 557 unsigned long); 558 559/* Set a field which starts at START and is LEN bits long. DATA and 560 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ 561static void 562put_field (unsigned char *data, enum floatformat_byteorders order, 563 unsigned int total_len, unsigned int start, unsigned int len, 564 unsigned long stuff_to_put) 565{ 566 unsigned int cur_byte; 567 int lo_bit, hi_bit; 568 int nextbyte = (order == floatformat_little) ? 1 : -1; 569 570 /* Start is in big-endian bit order! Fix that first. */ 571 start = total_len - (start + len); 572 573 /* Start at the least significant part of the field. */ 574 if (order == floatformat_little) 575 cur_byte = start / FLOATFORMAT_CHAR_BIT; 576 else 577 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; 578 579 lo_bit = start % FLOATFORMAT_CHAR_BIT; 580 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); 581 582 do 583 { 584 unsigned char *byte_ptr = data + cur_byte; 585 unsigned int bits = hi_bit - lo_bit; 586 unsigned int mask = ((1 << bits) - 1) << lo_bit; 587 *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask); 588 stuff_to_put >>= bits; 589 len -= bits; 590 cur_byte += nextbyte; 591 lo_bit = 0; 592 hi_bit = min (len, FLOATFORMAT_CHAR_BIT); 593 } 594 while (len != 0); 595} 596 597/* The converse: convert the double *FROM to an extended float 598 and store where TO points. Neither FROM nor TO have any alignment 599 restrictions. */ 600 601void 602floatformat_from_double (const struct floatformat *fmt, 603 const double *from, void *to) 604{ 605 double dfrom; 606 int exponent; 607 double mant; 608 unsigned int mant_bits, mant_off; 609 int mant_bits_left; 610 unsigned char *uto = (unsigned char *) to; 611 612 dfrom = *from; 613 memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT); 614 615 /* Split values are not handled specially, since a bottom half of 616 zero is correct for any value representable as double (in the 617 only supported case of split values). */ 618 619 /* If negative, set the sign bit. */ 620 if (dfrom < 0) 621 { 622 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1); 623 dfrom = -dfrom; 624 } 625 626 if (dfrom == 0) 627 { 628 /* 0.0. */ 629 return; 630 } 631 632 if (dfrom != dfrom) 633 { 634 /* NaN. */ 635 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 636 fmt->exp_len, fmt->exp_nan); 637 /* Be sure it's not infinity, but NaN value is irrelevant. */ 638 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start, 639 32, 1); 640 return; 641 } 642 643 if (dfrom + dfrom == dfrom) 644 { 645 /* This can only happen for an infinite value (or zero, which we 646 already handled above). */ 647 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 648 fmt->exp_len, fmt->exp_nan); 649 return; 650 } 651 652 mant = frexp (dfrom, &exponent); 653 if (exponent + fmt->exp_bias - 1 > 0) 654 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 655 fmt->exp_len, exponent + fmt->exp_bias - 1); 656 else 657 { 658 /* Handle a denormalized number. FIXME: What should we do for 659 non-IEEE formats? */ 660 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 661 fmt->exp_len, 0); 662 mant = ldexp (mant, exponent + fmt->exp_bias - 1); 663 } 664 665 mant_bits_left = fmt->man_len; 666 mant_off = fmt->man_start; 667 while (mant_bits_left > 0) 668 { 669 unsigned long mant_long; 670 mant_bits = mant_bits_left < 32 ? mant_bits_left : 32; 671 672 mant *= 4294967296.0; 673 mant_long = (unsigned long)mant; 674 mant -= mant_long; 675 676 /* If the integer bit is implicit, and we are not creating a 677 denormalized number, then we need to discard it. */ 678 if ((unsigned int) mant_bits_left == fmt->man_len 679 && fmt->intbit == floatformat_intbit_no 680 && exponent + fmt->exp_bias - 1 > 0) 681 { 682 mant_long &= 0x7fffffff; 683 mant_bits -= 1; 684 } 685 else if (mant_bits < 32) 686 { 687 /* The bits we want are in the most significant MANT_BITS bits of 688 mant_long. Move them to the least significant. */ 689 mant_long >>= 32 - mant_bits; 690 } 691 692 put_field (uto, fmt->byteorder, fmt->totalsize, 693 mant_off, mant_bits, mant_long); 694 mant_off += mant_bits; 695 mant_bits_left -= mant_bits; 696 } 697} 698 699/* Return non-zero iff the data at FROM is a valid number in format FMT. */ 700 701int 702floatformat_is_valid (const struct floatformat *fmt, const void *from) 703{ 704 return fmt->is_valid (fmt, from); 705} 706 707 708#ifdef IEEE_DEBUG 709 710#include <stdio.h> 711 712/* This is to be run on a host which uses IEEE floating point. */ 713 714void 715ieee_test (double n) 716{ 717 double result; 718 719 floatformat_to_double (&floatformat_ieee_double_little, &n, &result); 720 if ((n != result && (! isnan (n) || ! isnan (result))) 721 || (n < 0 && result >= 0) 722 || (n >= 0 && result < 0)) 723 printf ("Differ(to): %.20g -> %.20g\n", n, result); 724 725 floatformat_from_double (&floatformat_ieee_double_little, &n, &result); 726 if ((n != result && (! isnan (n) || ! isnan (result))) 727 || (n < 0 && result >= 0) 728 || (n >= 0 && result < 0)) 729 printf ("Differ(from): %.20g -> %.20g\n", n, result); 730 731#if 0 732 { 733 char exten[16]; 734 735 floatformat_from_double (&floatformat_m68881_ext, &n, exten); 736 floatformat_to_double (&floatformat_m68881_ext, exten, &result); 737 if (n != result) 738 printf ("Differ(to+from): %.20g -> %.20g\n", n, result); 739 } 740#endif 741 742#if IEEE_DEBUG > 1 743 /* This is to be run on a host which uses 68881 format. */ 744 { 745 long double ex = *(long double *)exten; 746 if (ex != n) 747 printf ("Differ(from vs. extended): %.20g\n", n); 748 } 749#endif 750} 751 752int 753main (void) 754{ 755 ieee_test (0.0); 756 ieee_test (0.5); 757 ieee_test (1.1); 758 ieee_test (256.0); 759 ieee_test (0.12345); 760 ieee_test (234235.78907234); 761 ieee_test (-512.0); 762 ieee_test (-0.004321); 763 ieee_test (1.2E-70); 764 ieee_test (1.2E-316); 765 ieee_test (4.9406564584124654E-324); 766 ieee_test (- 4.9406564584124654E-324); 767 ieee_test (- 0.0); 768 ieee_test (- INFINITY); 769 ieee_test (- NAN); 770 ieee_test (INFINITY); 771 ieee_test (NAN); 772 return 0; 773} 774#endif 775