gcc/dfp.c

   1 /* Decimal floating point support.
   2    Copyright (C) 2005, 2006, 2007, 2008, 2009 Free Software
   3    Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  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 "tm_p.h"
  28 #include "dfp.h"
  29
  30 /* The order of the following headers is important for making sure
  31    decNumber structure is large enough to hold decimal128 digits.  */
  32
  33 #include "decimal128.h"
  34 #include "decimal128Local.h"
  35 #include "decimal64.h"
  36 #include "decimal32.h"
  37 #include "decNumber.h"
  38
  39 #ifndef WORDS_BIGENDIAN
  40 #define WORDS_BIGENDIAN 0
  41 #endif
  42
  43 /* Initialize R (a real with the decimal flag set) from DN.  Can
  44    utilize status passed in via CONTEXT, if a previous operation had
  45    interesting status.  */
  46
  47 static void
  48 decimal_from_decnumber (REAL_VALUE_TYPE *r, decNumber *dn, decContext *context)
  49 {
  50   memset (r, 0, sizeof (REAL_VALUE_TYPE));
  51
  52   r->cl = rvc_normal;
  53   if (decNumberIsNaN (dn))
  54     r->cl = rvc_nan;
  55   if (decNumberIsInfinite (dn))
  56     r->cl = rvc_inf;
  57   if (context->status & DEC_Overflow)
  58     r->cl = rvc_inf;
  59   if (decNumberIsNegative (dn))
  60     r->sign = 1;
  61   r->decimal = 1;
  62
  63   if (r->cl != rvc_normal)
  64     return;
  65
  66   decContextDefault (context, DEC_INIT_DECIMAL128);
  67   context->traps = 0;
  68
  69   decimal128FromNumber ((decimal128 *) r->sig, dn, context);
  70 }
  71
  72 /* Create decimal encoded R from string S.  */
  73
  74 void
  75 decimal_real_from_string (REAL_VALUE_TYPE *r, const char *s)
  76 {
  77   decNumber dn;
  78   decContext set;
  79   decContextDefault (&set, DEC_INIT_DECIMAL128);
  80   set.traps = 0;
  81
  82   decNumberFromString (&dn, s, &set);
  83
  84   /* It would be more efficient to store directly in decNumber format,
  85      but that is impractical from current data structure size.
  86      Encoding as a decimal128 is much more compact.  */
  87   decimal_from_decnumber (r, &dn, &set);
  88 }
  89
  90 /* Initialize a decNumber from a REAL_VALUE_TYPE.  */
  91
  92 static void
  93 decimal_to_decnumber (const REAL_VALUE_TYPE *r, decNumber *dn)
  94 {
  95   decContext set;
  96   decContextDefault (&set, DEC_INIT_DECIMAL128);
  97   set.traps = 0;
  98
  99   switch (r->cl)
 100     {
 101     case rvc_zero:
 102       decNumberZero (dn);
 103       break;
 104     case rvc_inf:
 105       decNumberFromString (dn, "Infinity", &set);
 106       break;
 107     case rvc_nan:
 108       if (r->signalling)
 109         decNumberFromString (dn, "snan", &set);
 110       else
 111         decNumberFromString (dn, "nan", &set);
 112       break;
 113     case rvc_normal:
 114       gcc_assert (r->decimal);
 115       decimal128ToNumber ((const decimal128 *) r->sig, dn);
 116       break;
 117     default:
 118       gcc_unreachable ();
 119     }
 120
 121   /* Fix up sign bit.  */
 122   if (r->sign != decNumberIsNegative (dn))
 123     dn->bits ^= DECNEG;
 124 }
 125
 126 /* Encode a real into an IEEE 754 decimal32 type.  */
 127
 128 void
 129 encode_decimal32 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 130                   long *buf, const REAL_VALUE_TYPE *r)
 131 {
 132   decNumber dn;
 133   decimal32 d32;
 134   decContext set;
 135   int32_t image;
 136
 137   decContextDefault (&set, DEC_INIT_DECIMAL128);
 138   set.traps = 0;
 139
 140   decimal_to_decnumber (r, &dn);
 141   decimal32FromNumber (&d32, &dn, &set);
 142
 143   memcpy (&image, d32.bytes, sizeof (int32_t));
 144   buf[0] = image;
 145 }
 146
 147 /* Decode an IEEE 754 decimal32 type into a real.  */
 148
 149 void
 150 decode_decimal32 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 151                   REAL_VALUE_TYPE *r, const long *buf)
 152 {
 153   decNumber dn;
 154   decimal32 d32;
 155   decContext set;
 156   int32_t image;
 157
 158   decContextDefault (&set, DEC_INIT_DECIMAL128);
 159   set.traps = 0;
 160
 161   image = buf[0];
 162   memcpy (&d32.bytes, &image, sizeof (int32_t));
 163
 164   decimal32ToNumber (&d32, &dn);
 165   decimal_from_decnumber (r, &dn, &set);
 166 }
 167
 168 /* Encode a real into an IEEE 754 decimal64 type.  */
 169
 170 void
 171 encode_decimal64 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 172                   long *buf, const REAL_VALUE_TYPE *r)
 173 {
 174   decNumber dn;
 175   decimal64 d64;
 176   decContext set;
 177   int32_t image;
 178
 179   decContextDefault (&set, DEC_INIT_DECIMAL128);
 180   set.traps = 0;
 181
 182   decimal_to_decnumber (r, &dn);
 183   decimal64FromNumber (&d64, &dn, &set);
 184
 185   if (WORDS_BIGENDIAN == FLOAT_WORDS_BIG_ENDIAN)
 186     {
 187       memcpy (&image, &d64.bytes[0], sizeof (int32_t));
 188       buf[0] = image;
 189       memcpy (&image, &d64.bytes[4], sizeof (int32_t));
 190       buf[1] = image;
 191     }
 192   else
 193     {
 194       memcpy (&image, &d64.bytes[4], sizeof (int32_t));
 195       buf[0] = image;
 196       memcpy (&image, &d64.bytes[0], sizeof (int32_t));
 197       buf[1] = image;
 198     }
 199 }
 200
 201 /* Decode an IEEE 754 decimal64 type into a real.  */
 202
 203 void
 204 decode_decimal64 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 205                   REAL_VALUE_TYPE *r, const long *buf)
 206 {
 207   decNumber dn;
 208   decimal64 d64;
 209   decContext set;
 210   int32_t image;
 211
 212   decContextDefault (&set, DEC_INIT_DECIMAL128);
 213   set.traps = 0;
 214
 215   if (WORDS_BIGENDIAN == FLOAT_WORDS_BIG_ENDIAN)
 216     {
 217       image = buf[0];
 218       memcpy (&d64.bytes[0], &image, sizeof (int32_t));
 219       image = buf[1];
 220       memcpy (&d64.bytes[4], &image, sizeof (int32_t));
 221     }
 222   else
 223     {
 224       image = buf[1];
 225       memcpy (&d64.bytes[0], &image, sizeof (int32_t));
 226       image = buf[0];
 227       memcpy (&d64.bytes[4], &image, sizeof (int32_t));
 228     }
 229
 230   decimal64ToNumber (&d64, &dn);
 231   decimal_from_decnumber (r, &dn, &set);
 232 }
 233
 234 /* Encode a real into an IEEE 754 decimal128 type.  */
 235
 236 void
 237 encode_decimal128 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 238                    long *buf, const REAL_VALUE_TYPE *r)
 239 {
 240   decNumber dn;
 241   decContext set;
 242   decimal128 d128;
 243   int32_t image;
 244
 245   decContextDefault (&set, DEC_INIT_DECIMAL128);
 246   set.traps = 0;
 247
 248   decimal_to_decnumber (r, &dn);
 249   decimal128FromNumber (&d128, &dn, &set);
 250
 251   if (WORDS_BIGENDIAN == FLOAT_WORDS_BIG_ENDIAN)
 252     {
 253       memcpy (&image, &d128.bytes[0], sizeof (int32_t));
 254       buf[0] = image;
 255       memcpy (&image, &d128.bytes[4], sizeof (int32_t));
 256       buf[1] = image;
 257       memcpy (&image, &d128.bytes[8], sizeof (int32_t));
 258       buf[2] = image;
 259       memcpy (&image, &d128.bytes[12], sizeof (int32_t));
 260       buf[3] = image;
 261     }
 262   else
 263     {
 264       memcpy (&image, &d128.bytes[12], sizeof (int32_t));
 265       buf[0] = image;
 266       memcpy (&image, &d128.bytes[8], sizeof (int32_t));
 267       buf[1] = image;
 268       memcpy (&image, &d128.bytes[4], sizeof (int32_t));
 269       buf[2] = image;
 270       memcpy (&image, &d128.bytes[0], sizeof (int32_t));
 271       buf[3] = image;
 272     }
 273 }
 274
 275 /* Decode an IEEE 754 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   int32_t image;
 285
 286   decContextDefault (&set, DEC_INIT_DECIMAL128);
 287   set.traps = 0;
 288
 289   if (WORDS_BIGENDIAN == FLOAT_WORDS_BIG_ENDIAN)
 290     {
 291       image = buf[0];
 292       memcpy (&d128.bytes[0],  &image, sizeof (int32_t));
 293       image = buf[1];
 294       memcpy (&d128.bytes[4],  &image, sizeof (int32_t));
 295       image = buf[2];
 296       memcpy (&d128.bytes[8],  &image, sizeof (int32_t));
 297       image = buf[3];
 298       memcpy (&d128.bytes[12], &image, sizeof (int32_t));
 299     }
 300   else
 301     {
 302       image = buf[3];
 303       memcpy (&d128.bytes[0],  &image, sizeof (int32_t));
 304       image = buf[2];
 305       memcpy (&d128.bytes[4],  &image, sizeof (int32_t));
 306       image = buf[1];
 307       memcpy (&d128.bytes[8],  &image, sizeof (int32_t));
 308       image = buf[0];
 309       memcpy (&d128.bytes[12], &image, sizeof (int32_t));
 310     }
 311
 312   decimal128ToNumber (&d128, &dn);
 313   decimal_from_decnumber (r, &dn, &set);
 314 }
 315
 316 /* Helper function to convert from a binary real internal
 317    representation.  */
 318
 319 static void
 320 decimal_to_binary (REAL_VALUE_TYPE *to, const REAL_VALUE_TYPE *from,
 321                    enum machine_mode mode)
 322 {
 323   char string[256];
 324   const decimal128 *const d128 = (const decimal128 *) from->sig;
 325
 326   decimal128ToString (d128, string);
 327   real_from_string3 (to, string, mode);
 328 }
 329
 330
 331 /* Helper function to convert from a binary real internal
 332    representation.  */
 333
 334 static void
 335 decimal_from_binary (REAL_VALUE_TYPE *to, const REAL_VALUE_TYPE *from)
 336 {
 337   char string[256];
 338
 339   /* We convert to string, then to decNumber then to decimal128.  */
 340   real_to_decimal (string, from, sizeof (string), 0, 1);
 341   decimal_real_from_string (to, string);
 342 }
 343
 344 /* Helper function to real.c:do_compare() to handle decimal internal
 345    representation including when one of the operands is still in the
 346    binary internal representation.  */
 347
 348 int
 349 decimal_do_compare (const REAL_VALUE_TYPE *a, const REAL_VALUE_TYPE *b,
 350                     int nan_result)
 351 {
 352   decContext set;
 353   decNumber dn, dn2, dn3;
 354   REAL_VALUE_TYPE a1, b1;
 355
 356   /* If either operand is non-decimal, create temporary versions.  */
 357   if (!a->decimal)
 358     {
 359       decimal_from_binary (&a1, a);
 360       a = &a1;
 361     }
 362   if (!b->decimal)
 363     {
 364       decimal_from_binary (&b1, b);
 365       b = &b1;
 366     }
 367
 368   /* Convert into decNumber form for comparison operation.  */
 369   decContextDefault (&set, DEC_INIT_DECIMAL128);
 370   set.traps = 0;
 371   decimal128ToNumber ((const decimal128 *) a->sig, &dn2);
 372   decimal128ToNumber ((const decimal128 *) b->sig, &dn3);
 373
 374   /* Finally, do the comparison.  */
 375   decNumberCompare (&dn, &dn2, &dn3, &set);
 376
 377   /* Return the comparison result.  */
 378   if (decNumberIsNaN (&dn))
 379     return nan_result;
 380   else if (decNumberIsZero (&dn))
 381     return 0;
 382   else if (decNumberIsNegative (&dn))
 383     return -1;
 384   else
 385     return 1;
 386 }
 387
 388 /* Helper to round_for_format, handling decimal float types.  */
 389
 390 void
 391 decimal_round_for_format (const struct real_format *fmt, REAL_VALUE_TYPE *r)
 392 {
 393   decNumber dn;
 394   decContext set;
 395
 396   /* Real encoding occurs later.  */
 397   if (r->cl != rvc_normal)
 398     return;
 399
 400   decContextDefault (&set, DEC_INIT_DECIMAL128);
 401   set.traps = 0;
 402   decimal128ToNumber ((decimal128 *) r->sig, &dn);
 403
 404   if (fmt == &decimal_quad_format)
 405     {
 406       /* The internal format is already in this format.  */
 407       return;
 408     }
 409   else if (fmt == &decimal_single_format)
 410     {
 411       decimal32 d32;
 412       decContextDefault (&set, DEC_INIT_DECIMAL32);
 413       set.traps = 0;
 414
 415       decimal32FromNumber (&d32, &dn, &set);
 416       decimal32ToNumber (&d32, &dn);
 417     }
 418   else if (fmt == &decimal_double_format)
 419     {
 420       decimal64 d64;
 421       decContextDefault (&set, DEC_INIT_DECIMAL64);
 422       set.traps = 0;
 423
 424       decimal64FromNumber (&d64, &dn, &set);
 425       decimal64ToNumber (&d64, &dn);
 426     }
 427   else
 428     gcc_unreachable ();
 429
 430   decimal_from_decnumber (r, &dn, &set);
 431 }
 432
 433 /* Extend or truncate to a new mode.  Handles conversions between
 434    binary and decimal types.  */
 435
 436 void
 437 decimal_real_convert (REAL_VALUE_TYPE *r, enum machine_mode mode,
 438                       const REAL_VALUE_TYPE *a)
 439 {
 440   const struct real_format *fmt = REAL_MODE_FORMAT (mode);
 441
 442   if (a->decimal && fmt->b == 10)
 443     return;
 444   if (a->decimal)
 445       decimal_to_binary (r, a, mode);
 446   else
 447       decimal_from_binary (r, a);
 448 }
 449
 450 /* Render R_ORIG as a decimal floating point constant.  Emit DIGITS
 451    significant digits in the result, bounded by BUF_SIZE.  If DIGITS
 452    is 0, choose the maximum for the representation.  If
 453    CROP_TRAILING_ZEROS, strip trailing zeros.  Currently, not honoring
 454    DIGITS or CROP_TRAILING_ZEROS.  */
 455
 456 void
 457 decimal_real_to_decimal (char *str, const REAL_VALUE_TYPE *r_orig,
 458                          size_t buf_size,
 459                          size_t digits ATTRIBUTE_UNUSED,
 460                          int crop_trailing_zeros ATTRIBUTE_UNUSED)
 461 {
 462   const decimal128 *const d128 = (const decimal128*) r_orig->sig;
 463
 464   /* decimal128ToString requires space for at least 24 characters;
 465      Require two more for suffix.  */
 466   gcc_assert (buf_size >= 24);
 467   decimal128ToString (d128, str);
 468 }
 469
 470 static bool
 471 decimal_do_add (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 472                 const REAL_VALUE_TYPE *op1, int subtract_p)
 473 {
 474   decNumber dn;
 475   decContext set;
 476   decNumber dn2, dn3;
 477
 478   decimal_to_decnumber (op0, &dn2);
 479   decimal_to_decnumber (op1, &dn3);
 480
 481   decContextDefault (&set, DEC_INIT_DECIMAL128);
 482   set.traps = 0;
 483
 484   if (subtract_p)
 485     decNumberSubtract (&dn, &dn2, &dn3, &set);
 486   else
 487     decNumberAdd (&dn, &dn2, &dn3, &set);
 488
 489   decimal_from_decnumber (r, &dn, &set);
 490
 491   /* Return true, if inexact.  */
 492   return (set.status & DEC_Inexact);
 493 }
 494
 495 /* Compute R = OP0 * OP1.  */
 496
 497 static bool
 498 decimal_do_multiply (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 499                      const REAL_VALUE_TYPE *op1)
 500 {
 501   decContext set;
 502   decNumber dn, dn2, dn3;
 503
 504   decimal_to_decnumber (op0, &dn2);
 505   decimal_to_decnumber (op1, &dn3);
 506
 507   decContextDefault (&set, DEC_INIT_DECIMAL128);
 508   set.traps = 0;
 509
 510   decNumberMultiply (&dn, &dn2, &dn3, &set);
 511   decimal_from_decnumber (r, &dn, &set);
 512
 513   /* Return true, if inexact.  */
 514   return (set.status & DEC_Inexact);
 515 }
 516
 517 /* Compute R = OP0 / OP1.  */
 518
 519 static bool
 520 decimal_do_divide (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 521                    const REAL_VALUE_TYPE *op1)
 522 {
 523   decContext set;
 524   decNumber dn, dn2, dn3;
 525
 526   decimal_to_decnumber (op0, &dn2);
 527   decimal_to_decnumber (op1, &dn3);
 528
 529   decContextDefault (&set, DEC_INIT_DECIMAL128);
 530   set.traps = 0;
 531
 532   decNumberDivide (&dn, &dn2, &dn3, &set);
 533   decimal_from_decnumber (r, &dn, &set);
 534
 535   /* Return true, if inexact.  */
 536   return (set.status & DEC_Inexact);
 537 }
 538
 539 /* Set R to A truncated to an integral value toward zero (decimal
 540    floating point).  */
 541
 542 void
 543 decimal_do_fix_trunc (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *a)
 544 {
 545   decNumber dn, dn2;
 546   decContext set;
 547
 548   decContextDefault (&set, DEC_INIT_DECIMAL128);
 549   set.traps = 0;
 550   set.round = DEC_ROUND_DOWN;
 551   decimal128ToNumber ((const decimal128 *) a->sig, &dn2);
 552
 553   decNumberToIntegralValue (&dn, &dn2, &set);
 554   decimal_from_decnumber (r, &dn, &set);
 555 }
 556
 557 /* Render decimal float value R as an integer.  */
 558
 559 HOST_WIDE_INT
 560 decimal_real_to_integer (const REAL_VALUE_TYPE *r)
 561 {
 562   decContext set;
 563   decNumber dn, dn2, dn3;
 564   REAL_VALUE_TYPE to;
 565   char string[256];
 566
 567   decContextDefault (&set, DEC_INIT_DECIMAL128);
 568   set.traps = 0;
 569   set.round = DEC_ROUND_DOWN;
 570   decimal128ToNumber ((const decimal128 *) r->sig, &dn);
 571
 572   decNumberToIntegralValue (&dn2, &dn, &set);
 573   decNumberZero (&dn3);
 574   decNumberRescale (&dn, &dn2, &dn3, &set);
 575
 576   /* Convert to REAL_VALUE_TYPE and call appropriate conversion
 577      function.  */
 578   decNumberToString (&dn, string);
 579   real_from_string (&to, string);
 580   return real_to_integer (&to);
 581 }
 582
 583 /* Likewise, but to an integer pair, HI+LOW.  */
 584
 585 void
 586 decimal_real_to_integer2 (HOST_WIDE_INT *plow, HOST_WIDE_INT *phigh,
 587                           const REAL_VALUE_TYPE *r)
 588 {
 589   decContext set;
 590   decNumber dn, dn2, dn3;
 591   REAL_VALUE_TYPE to;
 592   char string[256];
 593
 594   decContextDefault (&set, DEC_INIT_DECIMAL128);
 595   set.traps = 0;
 596   set.round = DEC_ROUND_DOWN;
 597   decimal128ToNumber ((const decimal128 *) r->sig, &dn);
 598
 599   decNumberToIntegralValue (&dn2, &dn, &set);
 600   decNumberZero (&dn3);
 601   decNumberRescale (&dn, &dn2, &dn3, &set);
 602
 603   /* Convert to REAL_VALUE_TYPE and call appropriate conversion
 604      function.  */
 605   decNumberToString (&dn, string);
 606   real_from_string (&to, string);
 607   real_to_integer2 (plow, phigh, &to);
 608 }
 609
 610 /* Perform the decimal floating point operation described by CODE.
 611    For a unary operation, OP1 will be NULL.  This function returns
 612    true if the result may be inexact due to loss of precision.  */
 613
 614 bool
 615 decimal_real_arithmetic (REAL_VALUE_TYPE *r, enum tree_code code,
 616                          const REAL_VALUE_TYPE *op0,
 617                          const REAL_VALUE_TYPE *op1)
 618 {
 619   REAL_VALUE_TYPE a, b;
 620
 621   /* If either operand is non-decimal, create temporaries.  */
 622   if (!op0->decimal)
 623     {
 624       decimal_from_binary (&a, op0);
 625       op0 = &a;
 626     }
 627   if (op1 && !op1->decimal)
 628     {
 629       decimal_from_binary (&b, op1);
 630       op1 = &b;
 631     }
 632
 633   switch (code)
 634     {
 635     case PLUS_EXPR:
 636       return decimal_do_add (r, op0, op1, 0);
 637
 638     case MINUS_EXPR:
 639       return decimal_do_add (r, op0, op1, 1);
 640
 641     case MULT_EXPR:
 642       return decimal_do_multiply (r, op0, op1);
 643
 644     case RDIV_EXPR:
 645       return decimal_do_divide (r, op0, op1);
 646
 647     case MIN_EXPR:
 648       if (op1->cl == rvc_nan)
 649         *r = *op1;
 650       else if (real_compare (UNLT_EXPR, op0, op1))
 651         *r = *op0;
 652       else
 653         *r = *op1;
 654       return false;
 655
 656     case MAX_EXPR:
 657       if (op1->cl == rvc_nan)
 658         *r = *op1;
 659       else if (real_compare (LT_EXPR, op0, op1))
 660         *r = *op1;
 661       else
 662         *r = *op0;
 663       return false;
 664
 665     case NEGATE_EXPR:
 666       {
 667         *r = *op0;
 668         /* Flip sign bit.  */
 669         decimal128FlipSign ((decimal128 *) r->sig);
 670         /* Keep sign field in sync.  */
 671         r->sign ^= 1;
 672       }
 673       return false;
 674
 675     case ABS_EXPR:
 676       {
 677         *r = *op0;
 678         /* Clear sign bit.  */
 679         decimal128ClearSign ((decimal128 *) r->sig);
 680         /* Keep sign field in sync.  */
 681         r->sign = 0;
 682       }
 683       return false;
 684
 685     case FIX_TRUNC_EXPR:
 686       decimal_do_fix_trunc (r, op0);
 687       return false;
 688
 689     default:
 690       gcc_unreachable ();
 691     }
 692 }
 693
 694 /* Fills R with the largest finite value representable in mode MODE.
 695    If SIGN is nonzero, R is set to the most negative finite value.  */
 696
 697 void
 698 decimal_real_maxval (REAL_VALUE_TYPE *r, int sign, enum machine_mode mode)
 699 {
 700   const char *max;
 701
 702   switch (mode)
 703     {
 704     case SDmode:
 705       max = "9.999999E96";
 706       break;
 707     case DDmode:
 708       max = "9.999999999999999E384";
 709       break;
 710     case TDmode:
 711       max = "9.999999999999999999999999999999999E6144";
 712       break;
 713     default:
 714       gcc_unreachable ();
 715     }
 716
 717   decimal_real_from_string (r, max);
 718   if (sign)
 719     decimal128SetSign ((decimal128 *) r->sig, 1);
 720 }