floatformat.c revision 1.8
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 393const struct floatformat floatformat_bfloat16_big = 394{ 395 floatformat_big, 16, 0, 1, 8, 127, 255, 9, 7, 396 floatformat_intbit_no, 397 "floatformat_bfloat16_big", 398 floatformat_always_valid, 399 NULL 400}; 401 402const struct floatformat floatformat_bfloat16_little = 403{ 404 floatformat_little, 16, 0, 1, 8, 127, 255, 9, 7, 405 floatformat_intbit_no, 406 "floatformat_bfloat16_little", 407 floatformat_always_valid, 408 NULL 409}; 410 411#ifndef min 412#define min(a, b) ((a) < (b) ? (a) : (b)) 413#endif 414 415/* Return 1 if any bits are explicitly set in the mantissa of UFROM, 416 format FMT, 0 otherwise. */ 417static int 418mant_bits_set (const struct floatformat *fmt, const unsigned char *ufrom) 419{ 420 unsigned int mant_bits, mant_off; 421 int mant_bits_left; 422 423 mant_off = fmt->man_start; 424 mant_bits_left = fmt->man_len; 425 while (mant_bits_left > 0) 426 { 427 mant_bits = min (mant_bits_left, 32); 428 429 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, 430 mant_off, mant_bits) != 0) 431 return 1; 432 433 mant_off += mant_bits; 434 mant_bits_left -= mant_bits; 435 } 436 return 0; 437} 438 439/* Extract a field which starts at START and is LEN bits long. DATA and 440 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ 441static unsigned long 442get_field (const unsigned char *data, enum floatformat_byteorders order, 443 unsigned int total_len, unsigned int start, unsigned int len) 444{ 445 unsigned long result = 0; 446 unsigned int cur_byte; 447 int lo_bit, hi_bit, cur_bitshift = 0; 448 int nextbyte = (order == floatformat_little) ? 1 : -1; 449 450 /* Start is in big-endian bit order! Fix that first. */ 451 start = total_len - (start + len); 452 453 /* Start at the least significant part of the field. */ 454 if (order == floatformat_little) 455 cur_byte = start / FLOATFORMAT_CHAR_BIT; 456 else 457 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; 458 459 lo_bit = start % FLOATFORMAT_CHAR_BIT; 460 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); 461 462 do 463 { 464 unsigned int shifted = *(data + cur_byte) >> lo_bit; 465 unsigned int bits = hi_bit - lo_bit; 466 unsigned int mask = (1 << bits) - 1; 467 result |= (shifted & mask) << cur_bitshift; 468 len -= bits; 469 cur_bitshift += bits; 470 cur_byte += nextbyte; 471 lo_bit = 0; 472 hi_bit = min (len, FLOATFORMAT_CHAR_BIT); 473 } 474 while (len != 0); 475 476 return result; 477} 478 479/* Convert from FMT to a double. 480 FROM is the address of the extended float. 481 Store the double in *TO. */ 482 483void 484floatformat_to_double (const struct floatformat *fmt, 485 const void *from, double *to) 486{ 487 const unsigned char *ufrom = (const unsigned char *) from; 488 double dto; 489 long exponent; 490 unsigned long mant; 491 unsigned int mant_bits, mant_off; 492 int mant_bits_left; 493 494 /* Split values are not handled specially, since the top half has 495 the correctly rounded double value (in the only supported case of 496 split values). */ 497 498 exponent = get_field (ufrom, fmt->byteorder, fmt->totalsize, 499 fmt->exp_start, fmt->exp_len); 500 501 /* If the exponent indicates a NaN, we don't have information to 502 decide what to do. So we handle it like IEEE, except that we 503 don't try to preserve the type of NaN. FIXME. */ 504 if ((unsigned long) exponent == fmt->exp_nan) 505 { 506 int nan = mant_bits_set (fmt, ufrom); 507 508 /* On certain systems (such as GNU/Linux), the use of the 509 INFINITY macro below may generate a warning that cannot be 510 silenced due to a bug in GCC (PR preprocessor/11931). The 511 preprocessor fails to recognise the __extension__ keyword in 512 conjunction with the GNU/C99 extension for hexadecimal 513 floating point constants and will issue a warning when 514 compiling with -pedantic. */ 515 if (nan) 516 dto = NAN; 517 else 518 dto = INFINITY; 519 520 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) 521 dto = -dto; 522 523 *to = dto; 524 525 return; 526 } 527 528 mant_bits_left = fmt->man_len; 529 mant_off = fmt->man_start; 530 dto = 0.0; 531 532 /* Build the result algebraically. Might go infinite, underflow, etc; 533 who cares. */ 534 535 /* For denorms use minimum exponent. */ 536 if (exponent == 0) 537 exponent = 1 - fmt->exp_bias; 538 else 539 { 540 exponent -= fmt->exp_bias; 541 542 /* If this format uses a hidden bit, explicitly add it in now. 543 Otherwise, increment the exponent by one to account for the 544 integer bit. */ 545 546 if (fmt->intbit == floatformat_intbit_no) 547 dto = ldexp (1.0, exponent); 548 else 549 exponent++; 550 } 551 552 while (mant_bits_left > 0) 553 { 554 mant_bits = min (mant_bits_left, 32); 555 556 mant = get_field (ufrom, fmt->byteorder, fmt->totalsize, 557 mant_off, mant_bits); 558 559 dto += ldexp ((double) mant, exponent - mant_bits); 560 exponent -= mant_bits; 561 mant_off += mant_bits; 562 mant_bits_left -= mant_bits; 563 } 564 565 /* Negate it if negative. */ 566 if (get_field (ufrom, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1)) 567 dto = -dto; 568 *to = dto; 569} 570 571static void put_field (unsigned char *, enum floatformat_byteorders, 572 unsigned int, 573 unsigned int, 574 unsigned int, 575 unsigned long); 576 577/* Set a field which starts at START and is LEN bits long. DATA and 578 TOTAL_LEN are the thing we are extracting it from, in byteorder ORDER. */ 579static void 580put_field (unsigned char *data, enum floatformat_byteorders order, 581 unsigned int total_len, unsigned int start, unsigned int len, 582 unsigned long stuff_to_put) 583{ 584 unsigned int cur_byte; 585 int lo_bit, hi_bit; 586 int nextbyte = (order == floatformat_little) ? 1 : -1; 587 588 /* Start is in big-endian bit order! Fix that first. */ 589 start = total_len - (start + len); 590 591 /* Start at the least significant part of the field. */ 592 if (order == floatformat_little) 593 cur_byte = start / FLOATFORMAT_CHAR_BIT; 594 else 595 cur_byte = (total_len - start - 1) / FLOATFORMAT_CHAR_BIT; 596 597 lo_bit = start % FLOATFORMAT_CHAR_BIT; 598 hi_bit = min (lo_bit + len, FLOATFORMAT_CHAR_BIT); 599 600 do 601 { 602 unsigned char *byte_ptr = data + cur_byte; 603 unsigned int bits = hi_bit - lo_bit; 604 unsigned int mask = ((1 << bits) - 1) << lo_bit; 605 *byte_ptr = (*byte_ptr & ~mask) | ((stuff_to_put << lo_bit) & mask); 606 stuff_to_put >>= bits; 607 len -= bits; 608 cur_byte += nextbyte; 609 lo_bit = 0; 610 hi_bit = min (len, FLOATFORMAT_CHAR_BIT); 611 } 612 while (len != 0); 613} 614 615/* The converse: convert the double *FROM to an extended float 616 and store where TO points. Neither FROM nor TO have any alignment 617 restrictions. */ 618 619void 620floatformat_from_double (const struct floatformat *fmt, 621 const double *from, void *to) 622{ 623 double dfrom; 624 int exponent; 625 double mant; 626 unsigned int mant_bits, mant_off; 627 int mant_bits_left; 628 unsigned char *uto = (unsigned char *) to; 629 630 dfrom = *from; 631 memset (uto, 0, fmt->totalsize / FLOATFORMAT_CHAR_BIT); 632 633 /* Split values are not handled specially, since a bottom half of 634 zero is correct for any value representable as double (in the 635 only supported case of split values). */ 636 637 /* If negative, set the sign bit. */ 638 if (dfrom < 0) 639 { 640 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->sign_start, 1, 1); 641 dfrom = -dfrom; 642 } 643 644 if (dfrom == 0) 645 { 646 /* 0.0. */ 647 return; 648 } 649 650 if (dfrom != dfrom) 651 { 652 /* NaN. */ 653 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 654 fmt->exp_len, fmt->exp_nan); 655 /* Be sure it's not infinity, but NaN value is irrelevant. */ 656 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->man_start, 657 32, 1); 658 return; 659 } 660 661 if (dfrom + dfrom == dfrom) 662 { 663 /* This can only happen for an infinite value (or zero, which we 664 already handled above). */ 665 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 666 fmt->exp_len, fmt->exp_nan); 667 return; 668 } 669 670 mant = frexp (dfrom, &exponent); 671 if (exponent + fmt->exp_bias - 1 > 0) 672 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 673 fmt->exp_len, exponent + fmt->exp_bias - 1); 674 else 675 { 676 /* Handle a denormalized number. FIXME: What should we do for 677 non-IEEE formats? */ 678 put_field (uto, fmt->byteorder, fmt->totalsize, fmt->exp_start, 679 fmt->exp_len, 0); 680 mant = ldexp (mant, exponent + fmt->exp_bias - 1); 681 } 682 683 mant_bits_left = fmt->man_len; 684 mant_off = fmt->man_start; 685 while (mant_bits_left > 0) 686 { 687 unsigned long mant_long; 688 mant_bits = mant_bits_left < 32 ? mant_bits_left : 32; 689 690 mant *= 4294967296.0; 691 mant_long = (unsigned long)mant; 692 mant -= mant_long; 693 694 /* If the integer bit is implicit, and we are not creating a 695 denormalized number, then we need to discard it. */ 696 if ((unsigned int) mant_bits_left == fmt->man_len 697 && fmt->intbit == floatformat_intbit_no 698 && exponent + fmt->exp_bias - 1 > 0) 699 { 700 mant_long &= 0x7fffffff; 701 mant_bits -= 1; 702 } 703 else if (mant_bits < 32) 704 { 705 /* The bits we want are in the most significant MANT_BITS bits of 706 mant_long. Move them to the least significant. */ 707 mant_long >>= 32 - mant_bits; 708 } 709 710 put_field (uto, fmt->byteorder, fmt->totalsize, 711 mant_off, mant_bits, mant_long); 712 mant_off += mant_bits; 713 mant_bits_left -= mant_bits; 714 } 715} 716 717/* Return non-zero iff the data at FROM is a valid number in format FMT. */ 718 719int 720floatformat_is_valid (const struct floatformat *fmt, const void *from) 721{ 722 return fmt->is_valid (fmt, from); 723} 724 725 726#ifdef IEEE_DEBUG 727 728#include <stdio.h> 729 730/* This is to be run on a host which uses IEEE floating point. */ 731 732void 733ieee_test (double n) 734{ 735 double result; 736 737 floatformat_to_double (&floatformat_ieee_double_little, &n, &result); 738 if ((n != result && (! isnan (n) || ! isnan (result))) 739 || (n < 0 && result >= 0) 740 || (n >= 0 && result < 0)) 741 printf ("Differ(to): %.20g -> %.20g\n", n, result); 742 743 floatformat_from_double (&floatformat_ieee_double_little, &n, &result); 744 if ((n != result && (! isnan (n) || ! isnan (result))) 745 || (n < 0 && result >= 0) 746 || (n >= 0 && result < 0)) 747 printf ("Differ(from): %.20g -> %.20g\n", n, result); 748 749#if 0 750 { 751 char exten[16]; 752 753 floatformat_from_double (&floatformat_m68881_ext, &n, exten); 754 floatformat_to_double (&floatformat_m68881_ext, exten, &result); 755 if (n != result) 756 printf ("Differ(to+from): %.20g -> %.20g\n", n, result); 757 } 758#endif 759 760#if IEEE_DEBUG > 1 761 /* This is to be run on a host which uses 68881 format. */ 762 { 763 long double ex = *(long double *)exten; 764 if (ex != n) 765 printf ("Differ(from vs. extended): %.20g\n", n); 766 } 767#endif 768} 769 770int 771main (void) 772{ 773 ieee_test (0.0); 774 ieee_test (0.5); 775 ieee_test (1.1); 776 ieee_test (256.0); 777 ieee_test (0.12345); 778 ieee_test (234235.78907234); 779 ieee_test (-512.0); 780 ieee_test (-0.004321); 781 ieee_test (1.2E-70); 782 ieee_test (1.2E-316); 783 ieee_test (4.9406564584124654E-324); 784 ieee_test (- 4.9406564584124654E-324); 785 ieee_test (- 0.0); 786 ieee_test (- INFINITY); 787 ieee_test (- NAN); 788 ieee_test (INFINITY); 789 ieee_test (NAN); 790 return 0; 791} 792#endif 793