gcc/dfp.c

   1 /* Decimal floating point support.
   2    Copyright (C) 2005, 2006, 2007 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 2, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING.  If not, write to the Free
  18 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301, USA.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "tree.h"
  26 #include "toplev.h"
  27 #include "real.h"
  28 #include "tm_p.h"
  29 #include "dfp.h"
  30
  31 /* The order of the following headers is important for making sure
  32    decNumber structure is large enough to hold decimal128 digits.  */
  33
  34 #include "decimal128.h"
  35 #include "decimal64.h"
  36 #include "decimal32.h"
  37 #include "decNumber.h"
  38
  39 static uint32_t
  40 dfp_byte_swap (uint32_t in)
  41 {
  42   uint32_t out = 0;
  43   unsigned char *p = (unsigned char *) &out;
  44   union {
  45     uint32_t i;
  46     unsigned char b[4];
  47   } u;
  48
  49   u.i = in;
  50   p[0] = u.b[3];
  51   p[1] = u.b[2];
  52   p[2] = u.b[1];
  53   p[3] = u.b[0];
  54
  55   return out;
  56 }
  57
  58 /* Initialize R (a real with the decimal flag set) from DN.  Can
  59    utilize status passed in via CONTEXT, if a previous operation had
  60    interesting status.  */
  61
  62 static void
  63 decimal_from_decnumber (REAL_VALUE_TYPE *r, decNumber *dn, decContext *context)
  64 {
  65   memset (r, 0, sizeof (REAL_VALUE_TYPE));
  66
  67   r->cl = rvc_normal;
  68   if (decNumberIsZero (dn))
  69     r->cl = rvc_zero;
  70   if (decNumberIsNaN (dn))
  71     r->cl = rvc_nan;
  72   if (decNumberIsInfinite (dn))
  73     r->cl = rvc_inf;
  74   if (context->status & DEC_Overflow)
  75     r->cl = rvc_inf;
  76   if (decNumberIsNegative (dn))
  77     r->sign = 1;
  78   r->decimal = 1;
  79
  80   if (r->cl != rvc_normal)
  81     return;
  82
  83   decContextDefault (context, DEC_INIT_DECIMAL128);
  84   context->traps = 0;
  85
  86   decimal128FromNumber ((decimal128 *) r->sig, dn, context);
  87 }
  88
  89 /* Create decimal encoded R from string S.  */
  90
  91 void
  92 decimal_real_from_string (REAL_VALUE_TYPE *r, const char *s)
  93 {
  94   decNumber dn;
  95   decContext set;
  96   decContextDefault (&set, DEC_INIT_DECIMAL128);
  97   set.traps = 0;
  98
  99   decNumberFromString (&dn, s, &set);
 100
 101   /* It would be more efficient to store directly in decNumber format,
 102      but that is impractical from current data structure size.
 103      Encoding as a decimal128 is much more compact.  */
 104   decimal_from_decnumber (r, &dn, &set);
 105 }
 106
 107 /* Initialize a decNumber from a REAL_VALUE_TYPE.  */
 108
 109 static void
 110 decimal_to_decnumber (const REAL_VALUE_TYPE *r, decNumber *dn)
 111 {
 112   decContext set;
 113   decContextDefault (&set, DEC_INIT_DECIMAL128);
 114   set.traps = 0;
 115
 116   switch (r->cl)
 117     {
 118     case rvc_zero:
 119       decNumberZero (dn);
 120       break;
 121     case rvc_inf:
 122       decNumberFromString (dn, "Infinity", &set);
 123       break;
 124     case rvc_nan:
 125       if (r->signalling)
 126         decNumberFromString (dn, "snan", &set);
 127       else
 128         decNumberFromString (dn, "nan", &set);
 129       break;
 130     case rvc_normal:
 131       gcc_assert (r->decimal);
 132       decimal128ToNumber ((const decimal128 *) r->sig, dn);
 133       break;
 134     default:
 135       gcc_unreachable ();
 136     }
 137
 138   /* Fix up sign bit.  */
 139   if (r->sign != decNumberIsNegative (dn))
 140     dn->bits ^= DECNEG;
 141 }
 142
 143 /* Encode a real into an IEEE 754R decimal32 type.  */
 144
 145 void
 146 encode_decimal32 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 147                   long *buf, const REAL_VALUE_TYPE *r)
 148 {
 149   decNumber dn;
 150   decimal32 d32;
 151   decContext set;
 152
 153   decContextDefault (&set, DEC_INIT_DECIMAL128);
 154   set.traps = 0;
 155
 156   decimal_to_decnumber (r, &dn);
 157   decimal32FromNumber (&d32, &dn, &set);
 158
 159   if (FLOAT_WORDS_BIG_ENDIAN)
 160     buf[0] = *(uint32_t *) d32.bytes;
 161   else
 162     buf[0] = dfp_byte_swap (*(uint32_t *) d32.bytes);
 163 }
 164
 165 /* Decode an IEEE 754R decimal32 type into a real.  */
 166
 167 void
 168 decode_decimal32 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 169                   REAL_VALUE_TYPE *r, const long *buf)
 170 {
 171   decNumber dn;
 172   decimal32 d32;
 173   decContext set;
 174
 175   decContextDefault (&set, DEC_INIT_DECIMAL128);
 176   set.traps = 0;
 177
 178   if (FLOAT_WORDS_BIG_ENDIAN)
 179     *((uint32_t *) d32.bytes) = (uint32_t) buf[0];
 180   else
 181     *((uint32_t *) d32.bytes) = dfp_byte_swap ((uint32_t) buf[0]);
 182
 183   decimal32ToNumber (&d32, &dn);
 184   decimal_from_decnumber (r, &dn, &set);
 185 }
 186
 187 /* Encode a real into an IEEE 754R decimal64 type.  */
 188
 189 void
 190 encode_decimal64 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 191                   long *buf, const REAL_VALUE_TYPE *r)
 192 {
 193   decNumber dn;
 194   decimal64 d64;
 195   decContext set;
 196
 197   decContextDefault (&set, DEC_INIT_DECIMAL128);
 198   set.traps = 0;
 199
 200   decimal_to_decnumber (r, &dn);
 201   decimal64FromNumber (&d64, &dn, &set);
 202
 203   if (FLOAT_WORDS_BIG_ENDIAN)
 204     {
 205       buf[0] = *(uint32_t *) &d64.bytes[0];
 206       buf[1] = *(uint32_t *) &d64.bytes[4];
 207     }
 208   else
 209     {
 210       buf[1] = dfp_byte_swap (*(uint32_t *) &d64.bytes[0]);
 211       buf[0] = dfp_byte_swap (*(uint32_t *) &d64.bytes[4]);
 212     }
 213 }
 214
 215 /* Decode an IEEE 754R decimal64 type into a real.  */
 216
 217 void
 218 decode_decimal64 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 219                   REAL_VALUE_TYPE *r, const long *buf)
 220 {
 221   decNumber dn;
 222   decimal64 d64;
 223   decContext set;
 224
 225   decContextDefault (&set, DEC_INIT_DECIMAL128);
 226   set.traps = 0;
 227
 228   if (FLOAT_WORDS_BIG_ENDIAN)
 229     {
 230       *((uint32_t *) &d64.bytes[0]) = (uint32_t) buf[0];
 231       *((uint32_t *) &d64.bytes[4]) = (uint32_t) buf[1];
 232     }
 233   else
 234     {
 235       *((uint32_t *) &d64.bytes[0]) = dfp_byte_swap ((uint32_t) buf[1]);
 236       *((uint32_t *) &d64.bytes[4]) = dfp_byte_swap ((uint32_t) buf[0]);
 237     }
 238
 239   decimal64ToNumber (&d64, &dn);
 240   decimal_from_decnumber (r, &dn, &set);
 241 }
 242
 243 /* Encode a real into an IEEE 754R decimal128 type.  */
 244
 245 void
 246 encode_decimal128 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 247                    long *buf, const REAL_VALUE_TYPE *r)
 248 {
 249   decNumber dn;
 250   decContext set;
 251   decimal128 d128;
 252
 253   decContextDefault (&set, DEC_INIT_DECIMAL128);
 254   set.traps = 0;
 255
 256   decimal_to_decnumber (r, &dn);
 257   decimal128FromNumber (&d128, &dn, &set);
 258
 259   if (FLOAT_WORDS_BIG_ENDIAN)
 260     {
 261       buf[0] = *(uint32_t *) &d128.bytes[0];
 262       buf[1] = *(uint32_t *) &d128.bytes[4];
 263       buf[2] = *(uint32_t *) &d128.bytes[8];
 264       buf[3] = *(uint32_t *) &d128.bytes[12];
 265     }
 266   else
 267     {
 268       buf[0] = dfp_byte_swap (*(uint32_t *) &d128.bytes[12]);
 269       buf[1] = dfp_byte_swap (*(uint32_t *) &d128.bytes[8]);
 270       buf[2] = dfp_byte_swap (*(uint32_t *) &d128.bytes[4]);
 271       buf[3] = dfp_byte_swap (*(uint32_t *) &d128.bytes[0]);
 272     }
 273 }
 274
 275 /* Decode an IEEE 754R decimal128 type into a real.  */
 276
 277 void
 278 decode_decimal128 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 279                    REAL_VALUE_TYPE *r, const long *buf)
 280 {
 281   decNumber dn;
 282   decimal128 d128;
 283   decContext set;
 284
 285   decContextDefault (&set, DEC_INIT_DECIMAL128);
 286   set.traps = 0;
 287
 288   if (FLOAT_WORDS_BIG_ENDIAN)
 289     {
 290       *((uint32_t *) &d128.bytes[0])  = (uint32_t) buf[0];
 291       *((uint32_t *) &d128.bytes[4])  = (uint32_t) buf[1];
 292       *((uint32_t *) &d128.bytes[8])  = (uint32_t) buf[2];
 293       *((uint32_t *) &d128.bytes[12]) = (uint32_t) buf[3];
 294     }
 295   else
 296     {
 297       *((uint32_t *) &d128.bytes[0])  = dfp_byte_swap ((uint32_t) buf[3]);
 298       *((uint32_t *) &d128.bytes[4])  = dfp_byte_swap ((uint32_t) buf[2]);
 299       *((uint32_t *) &d128.bytes[8])  = dfp_byte_swap ((uint32_t) buf[1]);
 300       *((uint32_t *) &d128.bytes[12]) = dfp_byte_swap ((uint32_t) buf[0]);
 301     }
 302
 303   decimal128ToNumber (&d128, &dn);
 304   decimal_from_decnumber (r, &dn, &set);
 305 }
 306
 307 /* Helper function to convert from a binary real internal
 308    representation.  */
 309
 310 static void
 311 decimal_to_binary (REAL_VALUE_TYPE *to, const REAL_VALUE_TYPE *from,
 312                    enum machine_mode mode)
 313 {
 314   char string[256];
 315   const decimal128 *const d128 = (const decimal128 *) from->sig;
 316
 317   decimal128ToString (d128, string);
 318   real_from_string3 (to, string, mode);
 319 }
 320
 321
 322 /* Helper function to convert from a binary real internal
 323    representation.  */
 324
 325 static void
 326 decimal_from_binary (REAL_VALUE_TYPE *to, const REAL_VALUE_TYPE *from)
 327 {
 328   char string[256];
 329
 330   /* We convert to string, then to decNumber then to decimal128.  */
 331   real_to_decimal (string, from, sizeof (string), 0, 1);
 332   decimal_real_from_string (to, string);
 333 }
 334
 335 /* Helper function to real.c:do_compare() to handle decimal internal
 336    representation including when one of the operands is still in the
 337    binary internal representation.  */
 338
 339 int
 340 decimal_do_compare (const REAL_VALUE_TYPE *a, const REAL_VALUE_TYPE *b,
 341                     int nan_result)
 342 {
 343   decContext set;
 344   decNumber dn, dn2, dn3;
 345   REAL_VALUE_TYPE a1, b1;
 346
 347   /* If either operand is non-decimal, create temporary versions.  */
 348   if (!a->decimal)
 349     {
 350       decimal_from_binary (&a1, a);
 351       a = &a1;
 352     }
 353   if (!b->decimal)
 354     {
 355       decimal_from_binary (&b1, b);
 356       b = &b1;
 357     }
 358
 359   /* Convert into decNumber form for comparison operation.  */
 360   decContextDefault (&set, DEC_INIT_DECIMAL128);
 361   set.traps = 0;
 362   decimal128ToNumber ((const decimal128 *) a->sig, &dn2);
 363   decimal128ToNumber ((const decimal128 *) b->sig, &dn3);
 364
 365   /* Finally, do the comparison.  */
 366   decNumberCompare (&dn, &dn2, &dn3, &set);
 367
 368   /* Return the comparison result.  */
 369   if (decNumberIsNaN (&dn))
 370     return nan_result;
 371   else if (decNumberIsZero (&dn))
 372     return 0;
 373   else if (decNumberIsNegative (&dn))
 374     return -1;
 375   else
 376     return 1;
 377 }
 378
 379 /* Helper to round_for_format, handling decimal float types.  */
 380
 381 void
 382 decimal_round_for_format (const struct real_format *fmt, REAL_VALUE_TYPE *r)
 383 {
 384   decNumber dn;
 385   decContext set;
 386
 387   /* Real encoding occurs later.  */
 388   if (r->cl != rvc_normal)
 389     return;
 390
 391   decContextDefault (&set, DEC_INIT_DECIMAL128);
 392   set.traps = 0;
 393   decimal128ToNumber ((decimal128 *) r->sig, &dn);
 394
 395   if (fmt == &decimal_quad_format)
 396     {
 397       /* The internal format is already in this format.  */
 398       return;
 399     }
 400   else if (fmt == &decimal_single_format)
 401     {
 402       decimal32 d32;
 403       decContextDefault (&set, DEC_INIT_DECIMAL32);
 404       set.traps = 0;
 405
 406       decimal32FromNumber (&d32, &dn, &set);
 407       decimal32ToNumber (&d32, &dn);
 408     }
 409   else if (fmt == &decimal_double_format)
 410     {
 411       decimal64 d64;
 412       decContextDefault (&set, DEC_INIT_DECIMAL64);
 413       set.traps = 0;
 414
 415       decimal64FromNumber (&d64, &dn, &set);
 416       decimal64ToNumber (&d64, &dn);
 417     }
 418   else
 419     gcc_unreachable ();
 420
 421   decimal_from_decnumber (r, &dn, &set);
 422 }
 423
 424 /* Extend or truncate to a new mode.  Handles conversions between
 425    binary and decimal types.  */
 426
 427 void
 428 decimal_real_convert (REAL_VALUE_TYPE *r, enum machine_mode mode,
 429                       const REAL_VALUE_TYPE *a)
 430 {
 431   const struct real_format *fmt = REAL_MODE_FORMAT (mode);
 432
 433   if (a->decimal && fmt->b == 10)
 434     return;
 435   if (a->decimal)
 436       decimal_to_binary (r, a, mode);
 437   else
 438       decimal_from_binary (r, a);
 439 }
 440
 441 /* Render R_ORIG as a decimal floating point constant.  Emit DIGITS
 442    significant digits in the result, bounded by BUF_SIZE.  If DIGITS
 443    is 0, choose the maximum for the representation.  If
 444    CROP_TRAILING_ZEROS, strip trailing zeros.  Currently, not honoring
 445    DIGITS or CROP_TRAILING_ZEROS.  */
 446
 447 void
 448 decimal_real_to_decimal (char *str, const REAL_VALUE_TYPE *r_orig,
 449                          size_t buf_size,
 450                          size_t digits ATTRIBUTE_UNUSED,
 451                          int crop_trailing_zeros ATTRIBUTE_UNUSED)
 452 {
 453   const decimal128 *const d128 = (const decimal128*) r_orig->sig;
 454
 455   /* decimal128ToString requires space for at least 24 characters;
 456      Require two more for suffix.  */
 457   gcc_assert (buf_size >= 24);
 458   decimal128ToString (d128, str);
 459 }
 460
 461 static bool
 462 decimal_do_add (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 463                 const REAL_VALUE_TYPE *op1, int subtract_p)
 464 {
 465   decNumber dn;
 466   decContext set;
 467   decNumber dn2, dn3;
 468
 469   decimal_to_decnumber (op0, &dn2);
 470   decimal_to_decnumber (op1, &dn3);
 471
 472   decContextDefault (&set, DEC_INIT_DECIMAL128);
 473   set.traps = 0;
 474
 475   if (subtract_p)
 476     decNumberSubtract (&dn, &dn2, &dn3, &set);
 477   else
 478     decNumberAdd (&dn, &dn2, &dn3, &set);
 479
 480   decimal_from_decnumber (r, &dn, &set);
 481
 482   /* Return true, if inexact.  */
 483   return (set.status & DEC_Inexact);
 484 }
 485
 486 /* Compute R = OP0 * OP1.  */
 487
 488 static bool
 489 decimal_do_multiply (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 490                      const REAL_VALUE_TYPE *op1)
 491 {
 492   decContext set;
 493   decNumber dn, dn2, dn3;
 494
 495   decimal_to_decnumber (op0, &dn2);
 496   decimal_to_decnumber (op1, &dn3);
 497
 498   decContextDefault (&set, DEC_INIT_DECIMAL128);
 499   set.traps = 0;
 500
 501   decNumberMultiply (&dn, &dn2, &dn3, &set);
 502   decimal_from_decnumber (r, &dn, &set);
 503
 504   /* Return true, if inexact.  */
 505   return (set.status & DEC_Inexact);
 506 }
 507
 508 /* Compute R = OP0 / OP1.  */
 509
 510 static bool
 511 decimal_do_divide (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 512                    const REAL_VALUE_TYPE *op1)
 513 {
 514   decContext set;
 515   decNumber dn, dn2, dn3;
 516
 517   decimal_to_decnumber (op0, &dn2);
 518   decimal_to_decnumber (op1, &dn3);
 519
 520   decContextDefault (&set, DEC_INIT_DECIMAL128);
 521   set.traps = 0;
 522
 523   decNumberDivide (&dn, &dn2, &dn3, &set);
 524   decimal_from_decnumber (r, &dn, &set);
 525
 526   /* Return true, if inexact.  */
 527   return (set.status & DEC_Inexact);
 528 }
 529
 530 /* Set R to A truncated to an integral value toward zero (decimal
 531    floating point).  */
 532
 533 void
 534 decimal_do_fix_trunc (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *a)
 535 {
 536   decNumber dn, dn2;
 537   decContext set;
 538
 539   decContextDefault (&set, DEC_INIT_DECIMAL128);
 540   set.traps = 0;
 541   set.round = DEC_ROUND_DOWN;
 542   decimal128ToNumber ((const decimal128 *) a->sig, &dn2);
 543
 544   decNumberToIntegralValue (&dn, &dn2, &set);
 545   decimal_from_decnumber (r, &dn, &set);
 546 }
 547
 548 /* Render decimal float value R as an integer.  */
 549
 550 HOST_WIDE_INT
 551 decimal_real_to_integer (const REAL_VALUE_TYPE *r)
 552 {
 553   decContext set;
 554   decNumber dn, dn2, dn3;
 555   REAL_VALUE_TYPE to;
 556   char string[256];
 557
 558   decContextDefault (&set, DEC_INIT_DECIMAL128);
 559   set.traps = 0;
 560   set.round = DEC_ROUND_DOWN;
 561   decimal128ToNumber ((const decimal128 *) r->sig, &dn);
 562
 563   decNumberToIntegralValue (&dn2, &dn, &set);
 564   decNumberZero (&dn3);
 565   decNumberRescale (&dn, &dn2, &dn3, &set);
 566
 567   /* Convert to REAL_VALUE_TYPE and call appropriate conversion
 568      function.  */
 569   decNumberToString (&dn, string);
 570   real_from_string (&to, string);
 571   return real_to_integer (&to);
 572 }
 573
 574 /* Likewise, but to an integer pair, HI+LOW.  */
 575
 576 void
 577 decimal_real_to_integer2 (HOST_WIDE_INT *plow, HOST_WIDE_INT *phigh,
 578                           const REAL_VALUE_TYPE *r)
 579 {
 580   decContext set;
 581   decNumber dn, dn2, dn3;
 582   REAL_VALUE_TYPE to;
 583   char string[256];
 584
 585   decContextDefault (&set, DEC_INIT_DECIMAL128);
 586   set.traps = 0;
 587   set.round = DEC_ROUND_DOWN;
 588   decimal128ToNumber ((const decimal128 *) r->sig, &dn);
 589
 590   decNumberToIntegralValue (&dn2, &dn, &set);
 591   decNumberZero (&dn3);
 592   decNumberRescale (&dn, &dn2, &dn3, &set);
 593
 594   /* Conver to REAL_VALUE_TYPE and call appropriate conversion
 595      function.  */
 596   decNumberToString (&dn, string);
 597   real_from_string (&to, string);
 598   real_to_integer2 (plow, phigh, &to);
 599 }
 600
 601 /* Perform the decimal floating point operation described by CODE.
 602    For a unary operation, OP1 will be NULL.  This function returns
 603    true if the result may be inexact due to loss of precision.  */
 604
 605 bool
 606 decimal_real_arithmetic (REAL_VALUE_TYPE *r, enum tree_code code,
 607                          const REAL_VALUE_TYPE *op0,
 608                          const REAL_VALUE_TYPE *op1)
 609 {
 610   REAL_VALUE_TYPE a, b;
 611
 612   /* If either operand is non-decimal, create temporaries.  */
 613   if (!op0->decimal)
 614     {
 615       decimal_from_binary (&a, op0);
 616       op0 = &a;
 617     }
 618   if (op1 && !op1->decimal)
 619     {
 620       decimal_from_binary (&b, op1);
 621       op1 = &b;
 622     }
 623
 624   switch (code)
 625     {
 626     case PLUS_EXPR:
 627       return decimal_do_add (r, op0, op1, 0);
 628
 629     case MINUS_EXPR:
 630       return decimal_do_add (r, op0, op1, 1);
 631
 632     case MULT_EXPR:
 633       return decimal_do_multiply (r, op0, op1);
 634
 635     case RDIV_EXPR:
 636       return decimal_do_divide (r, op0, op1);
 637
 638     case MIN_EXPR:
 639       if (op1->cl == rvc_nan)
 640         *r = *op1;
 641       else if (real_compare (UNLT_EXPR, op0, op1))
 642         *r = *op0;
 643       else
 644         *r = *op1;
 645       return false;
 646
 647     case MAX_EXPR:
 648       if (op1->cl == rvc_nan)
 649         *r = *op1;
 650       else if (real_compare (LT_EXPR, op0, op1))
 651         *r = *op1;
 652       else
 653         *r = *op0;
 654       return false;
 655
 656     case NEGATE_EXPR:
 657       {
 658         *r = *op0;
 659         /* Flip sign bit.  */
 660         decimal128FlipSign ((decimal128 *) r->sig);
 661         /* Keep sign field in sync.  */
 662         r->sign ^= 1;
 663       }
 664       return false;
 665
 666     case ABS_EXPR:
 667       {
 668         *r = *op0;
 669         /* Clear sign bit.  */
 670         decimal128ClearSign ((decimal128 *) r->sig);
 671         /* Keep sign field in sync.  */
 672         r->sign = 0;
 673       }
 674       return false;
 675
 676     case FIX_TRUNC_EXPR:
 677       decimal_do_fix_trunc (r, op0);
 678       return false;
 679
 680     default:
 681       gcc_unreachable ();
 682     }
 683 }
 684
 685 /* Fills R with the largest finite value representable in mode MODE.
 686    If SIGN is nonzero, R is set to the most negative finite value.  */
 687
 688 void
 689 decimal_real_maxval (REAL_VALUE_TYPE *r, int sign, enum machine_mode mode)
 690 {
 691   const char *max;
 692
 693   switch (mode)
 694     {
 695     case SDmode:
 696       max = "9.999999E96";
 697       break;
 698     case DDmode:
 699       max = "9.999999999999999E384";
 700       break;
 701     case TDmode:
 702       max = "9.999999999999999999999999999999999E6144";
 703       break;
 704     default:
 705       gcc_unreachable ();
 706     }
 707
 708   decimal_real_from_string (r, max);
 709   if (sign)
 710     decimal128SetSign ((decimal128 *) r->sig, 1);
 711 }