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 3, 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 COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "tm.h"
  24 #include "tree.h"
  25 #include "toplev.h"
  26 #include "real.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 "decimal64.h"
  35 #include "decimal32.h"
  36 #include "decNumber.h"
  37
  38 static uint32_t
  39 dfp_byte_swap (uint32_t in)
  40 {
  41   uint32_t out = 0;
  42   unsigned char *p = (unsigned char *) &out;
  43   union {
  44     uint32_t i;
  45     unsigned char b[4];
  46   } u;
  47
  48   u.i = in;
  49   p[0] = u.b[3];
  50   p[1] = u.b[2];
  51   p[2] = u.b[1];
  52   p[3] = u.b[0];
  53
  54   return out;
  55 }
  56
  57 /* Initialize R (a real with the decimal flag set) from DN.  Can
  58    utilize status passed in via CONTEXT, if a previous operation had
  59    interesting status.  */
  60
  61 static void
  62 decimal_from_decnumber (REAL_VALUE_TYPE *r, decNumber *dn, decContext *context)
  63 {
  64   memset (r, 0, sizeof (REAL_VALUE_TYPE));
  65
  66   r->cl = rvc_normal;
  67   if (decNumberIsZero (dn))
  68     r->cl = rvc_zero;
  69   if (decNumberIsNaN (dn))
  70     r->cl = rvc_nan;
  71   if (decNumberIsInfinite (dn))
  72     r->cl = rvc_inf;
  73   if (context->status & DEC_Overflow)
  74     r->cl = rvc_inf;
  75   if (decNumberIsNegative (dn))
  76     r->sign = 1;
  77   r->decimal = 1;
  78
  79   if (r->cl != rvc_normal)
  80     return;
  81
  82   decContextDefault (context, DEC_INIT_DECIMAL128);
  83   context->traps = 0;
  84
  85   decimal128FromNumber ((decimal128 *) r->sig, dn, context);
  86 }
  87
  88 /* Create decimal encoded R from string S.  */
  89
  90 void
  91 decimal_real_from_string (REAL_VALUE_TYPE *r, const char *s)
  92 {
  93   decNumber dn;
  94   decContext set;
  95   decContextDefault (&set, DEC_INIT_DECIMAL128);
  96   set.traps = 0;
  97
  98   decNumberFromString (&dn, (char *) s, &set);
  99
 100   /* It would be more efficient to store directly in decNumber format,
 101      but that is impractical from current data structure size.
 102      Encoding as a decimal128 is much more compact.  */
 103   decimal_from_decnumber (r, &dn, &set);
 104 }
 105
 106 /* Initialize a decNumber from a REAL_VALUE_TYPE.  */
 107
 108 static void
 109 decimal_to_decnumber (const REAL_VALUE_TYPE *r, decNumber *dn)
 110 {
 111   decContext set;
 112   decContextDefault (&set, DEC_INIT_DECIMAL128);
 113   set.traps = 0;
 114
 115   switch (r->cl)
 116     {
 117     case rvc_zero:
 118       decNumberZero (dn);
 119       break;
 120     case rvc_inf:
 121       decNumberFromString (dn, (char *)"Infinity", &set);
 122       break;
 123     case rvc_nan:
 124       if (r->signalling)
 125         decNumberFromString (dn, (char *)"snan", &set);
 126       else
 127         decNumberFromString (dn, (char *)"nan", &set);
 128       break;
 129     case rvc_normal:
 130       gcc_assert (r->decimal);
 131       decimal128ToNumber ((decimal128 *) r->sig, dn);
 132       break;
 133     default:
 134       gcc_unreachable ();
 135     }
 136
 137   /* Fix up sign bit.  */
 138   if (r->sign != decNumberIsNegative (dn))
 139     dn->bits ^= DECNEG;
 140 }
 141
 142 /* Encode a real into an IEEE 754R decimal32 type.  */
 143
 144 void
 145 encode_decimal32 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 146                   long *buf, const REAL_VALUE_TYPE *r)
 147 {
 148   decNumber dn;
 149   decimal32 d32;
 150   decContext set;
 151
 152   decContextDefault (&set, DEC_INIT_DECIMAL128);
 153   set.traps = 0;
 154
 155   decimal_to_decnumber (r, &dn);
 156   decimal32FromNumber (&d32, &dn, &set);
 157
 158   if (FLOAT_WORDS_BIG_ENDIAN)
 159     buf[0] = *(uint32_t *) d32.bytes;
 160   else
 161     buf[0] = dfp_byte_swap (*(uint32_t *) d32.bytes);
 162 }
 163
 164 /* Decode an IEEE 754R decimal32 type into a real.  */
 165
 166 void
 167 decode_decimal32 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 168                   REAL_VALUE_TYPE *r, const long *buf)
 169 {
 170   decNumber dn;
 171   decimal32 d32;
 172   decContext set;
 173
 174   decContextDefault (&set, DEC_INIT_DECIMAL128);
 175   set.traps = 0;
 176
 177   if (FLOAT_WORDS_BIG_ENDIAN)
 178     *((uint32_t *) d32.bytes) = (uint32_t) buf[0];
 179   else
 180     *((uint32_t *) d32.bytes) = dfp_byte_swap ((uint32_t) buf[0]);
 181
 182   decimal32ToNumber (&d32, &dn);
 183   decimal_from_decnumber (r, &dn, &set);
 184 }
 185
 186 /* Encode a real into an IEEE 754R decimal64 type.  */
 187
 188 void
 189 encode_decimal64 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 190                   long *buf, const REAL_VALUE_TYPE *r)
 191 {
 192   decNumber dn;
 193   decimal64 d64;
 194   decContext set;
 195
 196   decContextDefault (&set, DEC_INIT_DECIMAL128);
 197   set.traps = 0;
 198
 199   decimal_to_decnumber (r, &dn);
 200   decimal64FromNumber (&d64, &dn, &set);
 201
 202   if (FLOAT_WORDS_BIG_ENDIAN)
 203     {
 204       buf[0] = *(uint32_t *) &d64.bytes[0];
 205       buf[1] = *(uint32_t *) &d64.bytes[4];
 206     }
 207   else
 208     {
 209       buf[1] = dfp_byte_swap (*(uint32_t *) &d64.bytes[0]);
 210       buf[0] = dfp_byte_swap (*(uint32_t *) &d64.bytes[4]);
 211     }
 212 }
 213
 214 /* Decode an IEEE 754R decimal64 type into a real.  */
 215
 216 void
 217 decode_decimal64 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 218                   REAL_VALUE_TYPE *r, const long *buf)
 219 {
 220   decNumber dn;
 221   decimal64 d64;
 222   decContext set;
 223
 224   decContextDefault (&set, DEC_INIT_DECIMAL128);
 225   set.traps = 0;
 226
 227   if (FLOAT_WORDS_BIG_ENDIAN)
 228     {
 229       *((uint32_t *) &d64.bytes[0]) = (uint32_t) buf[0];
 230       *((uint32_t *) &d64.bytes[4]) = (uint32_t) buf[1];
 231     }
 232   else
 233     {
 234       *((uint32_t *) &d64.bytes[0]) = dfp_byte_swap ((uint32_t) buf[1]);
 235       *((uint32_t *) &d64.bytes[4]) = dfp_byte_swap ((uint32_t) buf[0]);
 236     }
 237
 238   decimal64ToNumber (&d64, &dn);
 239   decimal_from_decnumber (r, &dn, &set);
 240 }
 241
 242 /* Encode a real into an IEEE 754R decimal128 type.  */
 243
 244 void
 245 encode_decimal128 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 246                    long *buf, const REAL_VALUE_TYPE *r)
 247 {
 248   decNumber dn;
 249   decContext set;
 250   decimal128 d128;
 251
 252   decContextDefault (&set, DEC_INIT_DECIMAL128);
 253   set.traps = 0;
 254
 255   decimal_to_decnumber (r, &dn);
 256   decimal128FromNumber (&d128, &dn, &set);
 257
 258   if (FLOAT_WORDS_BIG_ENDIAN)
 259     {
 260       buf[0] = *(uint32_t *) &d128.bytes[0];
 261       buf[1] = *(uint32_t *) &d128.bytes[4];
 262       buf[2] = *(uint32_t *) &d128.bytes[8];
 263       buf[3] = *(uint32_t *) &d128.bytes[12];
 264     }
 265   else
 266     {
 267       buf[0] = dfp_byte_swap (*(uint32_t *) &d128.bytes[12]);
 268       buf[1] = dfp_byte_swap (*(uint32_t *) &d128.bytes[8]);
 269       buf[2] = dfp_byte_swap (*(uint32_t *) &d128.bytes[4]);
 270       buf[3] = dfp_byte_swap (*(uint32_t *) &d128.bytes[0]);
 271     }
 272 }
 273
 274 /* Decode an IEEE 754R decimal128 type into a real.  */
 275
 276 void
 277 decode_decimal128 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 278                    REAL_VALUE_TYPE *r, const long *buf)
 279 {
 280   decNumber dn;
 281   decimal128 d128;
 282   decContext set;
 283
 284   decContextDefault (&set, DEC_INIT_DECIMAL128);
 285   set.traps = 0;
 286
 287   if (FLOAT_WORDS_BIG_ENDIAN)
 288     {
 289       *((uint32_t *) &d128.bytes[0])  = (uint32_t) buf[0];
 290       *((uint32_t *) &d128.bytes[4])  = (uint32_t) buf[1];
 291       *((uint32_t *) &d128.bytes[8])  = (uint32_t) buf[2];
 292       *((uint32_t *) &d128.bytes[12]) = (uint32_t) buf[3];
 293     }
 294   else
 295     {
 296       *((uint32_t *) &d128.bytes[0])  = dfp_byte_swap ((uint32_t) buf[3]);
 297       *((uint32_t *) &d128.bytes[4])  = dfp_byte_swap ((uint32_t) buf[2]);
 298       *((uint32_t *) &d128.bytes[8])  = dfp_byte_swap ((uint32_t) buf[1]);
 299       *((uint32_t *) &d128.bytes[12]) = dfp_byte_swap ((uint32_t) buf[0]);
 300     }
 301
 302   decimal128ToNumber (&d128, &dn);
 303   decimal_from_decnumber (r, &dn, &set);
 304 }
 305
 306 /* Helper function to convert from a binary real internal
 307    representation.  */
 308
 309 static void
 310 decimal_to_binary (REAL_VALUE_TYPE *to, const REAL_VALUE_TYPE *from,
 311                    enum machine_mode mode)
 312 {
 313   char string[256];
 314   decimal128 *d128;
 315   d128 = (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 ((decimal128 *) a->sig, &dn2);
 363   decimal128ToNumber ((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   decimal128 *d128 = (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 ((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 ((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 ((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         decimal128 *d128;
 659         *r = *op0;
 660         d128 = (decimal128 *) r->sig;
 661         /* Flip high bit.  */
 662         d128->bytes[0] ^= 1 << 7;
 663         /* Keep sign field in sync.  */
 664         r->sign ^= 1;
 665       }
 666       return false;
 667
 668     case ABS_EXPR:
 669       {
 670         decimal128 *d128;
 671         *r = *op0;
 672         d128 = (decimal128 *) r->sig;
 673         /* Clear high bit.  */
 674         d128->bytes[0] &= 0x7f;
 675         /* Keep sign field in sync.  */
 676         r->sign = 0;
 677       }
 678       return false;
 679
 680     case FIX_TRUNC_EXPR:
 681       decimal_do_fix_trunc (r, op0);
 682       return false;
 683
 684     default:
 685       gcc_unreachable ();
 686     }
 687 }
 688
 689 /* Fills R with the largest finite value representable in mode MODE.
 690    If SIGN is nonzero, R is set to the most negative finite value.  */
 691
 692 void
 693 decimal_real_maxval (REAL_VALUE_TYPE *r, int sign, enum machine_mode mode)
 694 {
 695   char *max;
 696
 697   switch (mode)
 698     {
 699     case SDmode:
 700       max = (char *) "9.999999E96";
 701       break;
 702     case DDmode:
 703       max = (char *) "9.999999999999999E384";
 704       break;
 705     case TDmode:
 706       max = (char *) "9.999999999999999999999999999999999E6144";
 707       break;
 708     default:
 709       gcc_unreachable ();
 710     }
 711
 712   decimal_real_from_string (r, max);
 713   if (sign)
 714     r->sig[0] |= 0x80000000;
 715 }