gcc/dfp.c

   1 /* Decimal floating point support.
   2    Copyright (C) 2005, 2006 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, (char *) 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, (char *)"Infinity", &set);
 123       break;
 124     case rvc_nan:
 125       if (r->signalling)
 126         decNumberFromString (dn, (char *)"snan", &set);
 127       else
 128         decNumberFromString (dn, (char *)"nan", &set);
 129       break;
 130     case rvc_normal:
 131       gcc_assert (r->decimal);
 132       decimal128ToNumber ((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     decNumberNegate (dn);
 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 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 decimal_real_to_decimal (char *str, const REAL_VALUE_TYPE *r_orig,
 448                               size_t buf_size,
 449                               size_t digits ATTRIBUTE_UNUSED,
 450                               int crop_trailing_zeros ATTRIBUTE_UNUSED)
 451 {
 452   decimal128 *d128 = (decimal128*) r_orig->sig;
 453
 454   /* decimal128ToString requires space for at least 24 characters;
 455      Require two more for suffix.  */
 456   gcc_assert (buf_size >= 24);
 457   decimal128ToString (d128, str);
 458 }
 459
 460 static bool
 461 decimal_do_add (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 462                 const REAL_VALUE_TYPE *op1, int subtract_p)
 463 {
 464   decNumber dn;
 465   decContext set;
 466   decNumber dn2, dn3;
 467
 468   decimal_to_decnumber (op0, &dn2);
 469   decimal_to_decnumber (op1, &dn3);
 470
 471   decContextDefault (&set, DEC_INIT_DECIMAL128);
 472   set.traps = 0;
 473
 474   if (subtract_p)
 475     decNumberSubtract (&dn, &dn2, &dn3, &set);
 476   else
 477     decNumberAdd (&dn, &dn2, &dn3, &set);
 478
 479   decimal_from_decnumber (r, &dn, &set);
 480
 481   /* Return true, if inexact.  */
 482   return (set.status & DEC_Inexact);
 483 }
 484
 485 /* Compute R = OP0 * OP1.  */
 486
 487 static bool
 488 decimal_do_multiply (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 489                      const REAL_VALUE_TYPE *op1)
 490 {
 491   decContext set;
 492   decNumber dn, dn2, dn3;
 493
 494   decimal_to_decnumber (op0, &dn2);
 495   decimal_to_decnumber (op1, &dn3);
 496
 497   decContextDefault (&set, DEC_INIT_DECIMAL128);
 498   set.traps = 0;
 499
 500   decNumberMultiply (&dn, &dn2, &dn3, &set);
 501   decimal_from_decnumber (r, &dn, &set);
 502
 503   /* Return true, if inexact.  */
 504   return (set.status & DEC_Inexact);
 505 }
 506
 507 /* Compute R = OP0 / OP1.  */
 508
 509 static bool
 510 decimal_do_divide (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 511                    const REAL_VALUE_TYPE *op1)
 512 {
 513   decContext set;
 514   decNumber dn, dn2, dn3;
 515
 516   decimal_to_decnumber (op0, &dn2);
 517   decimal_to_decnumber (op1, &dn3);
 518
 519   decContextDefault (&set, DEC_INIT_DECIMAL128);
 520   set.traps = 0;
 521
 522   decNumberDivide (&dn, &dn2, &dn3, &set);
 523   decimal_from_decnumber (r, &dn, &set);
 524
 525   /* Return true, if inexact.  */
 526   return (set.status & DEC_Inexact);
 527 }
 528
 529 /* Set R to A truncated to an integral value toward zero (decimal
 530    floating point).  */
 531
 532 void
 533 decimal_do_fix_trunc (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *a)
 534 {
 535   decNumber dn, dn2;
 536   decContext set;
 537
 538   decContextDefault (&set, DEC_INIT_DECIMAL128);
 539   set.traps = 0;
 540   set.round = DEC_ROUND_DOWN;
 541   decimal128ToNumber ((decimal128 *) a->sig, &dn2);
 542
 543   decNumberToIntegralValue (&dn, &dn2, &set);
 544   decimal_from_decnumber (r, &dn, &set);
 545 }
 546
 547 /* Render decimal float value R as an integer.  */
 548
 549 HOST_WIDE_INT
 550 decimal_real_to_integer (const REAL_VALUE_TYPE *r)
 551 {
 552   decContext set;
 553   decNumber dn, dn2, dn3;
 554   REAL_VALUE_TYPE to;
 555   char string[256];
 556
 557   decContextDefault (&set, DEC_INIT_DECIMAL128);
 558   set.traps = 0;
 559   set.round = DEC_ROUND_DOWN;
 560   decimal128ToNumber ((decimal128 *) r->sig, &dn);
 561
 562   decNumberToIntegralValue (&dn2, &dn, &set);
 563   decNumberZero (&dn3);
 564   decNumberRescale (&dn, &dn2, &dn3, &set);
 565
 566   /* Convert to REAL_VALUE_TYPE and call appropriate conversion
 567      function.  */
 568   decNumberToString (&dn, string);
 569   real_from_string (&to, string);
 570   return real_to_integer (&to);
 571 }
 572
 573 /* Likewise, but to an integer pair, HI+LOW.  */
 574
 575 void
 576 decimal_real_to_integer2 (HOST_WIDE_INT *plow, HOST_WIDE_INT *phigh,
 577                           const REAL_VALUE_TYPE *r)
 578 {
 579   decContext set;
 580   decNumber dn, dn2, dn3;
 581   REAL_VALUE_TYPE to;
 582   char string[256];
 583
 584   decContextDefault (&set, DEC_INIT_DECIMAL128);
 585   set.traps = 0;
 586   set.round = DEC_ROUND_DOWN;
 587   decimal128ToNumber ((decimal128 *) r->sig, &dn);
 588
 589   decNumberToIntegralValue (&dn2, &dn, &set);
 590   decNumberZero (&dn3);
 591   decNumberRescale (&dn, &dn2, &dn3, &set);
 592
 593   /* Conver to REAL_VALUE_TYPE and call appropriate conversion
 594      function.  */
 595   decNumberToString (&dn, string);
 596   real_from_string (&to, string);
 597   real_to_integer2 (plow, phigh, &to);
 598 }
 599
 600 /* Perform the decimal floating point operation described by CODE.
 601    For a unary operation, OP1 will be NULL.  This function returns
 602    true if the result may be inexact due to loss of precision.  */
 603
 604 bool
 605 decimal_real_arithmetic (REAL_VALUE_TYPE *r, enum tree_code code,
 606                          const REAL_VALUE_TYPE *op0,
 607                          const REAL_VALUE_TYPE *op1)
 608 {
 609   REAL_VALUE_TYPE a, b;
 610
 611   /* If either operand is non-decimal, create temporaries.  */
 612   if (!op0->decimal)
 613     {
 614       decimal_from_binary (&a, op0);
 615       op0 = &a;
 616     }
 617   if (op1 && !op1->decimal)
 618     {
 619       decimal_from_binary (&b, op1);
 620       op1 = &b;
 621     }
 622
 623   switch (code)
 624     {
 625     case PLUS_EXPR:
 626       return decimal_do_add (r, op0, op1, 0);
 627
 628     case MINUS_EXPR:
 629       return decimal_do_add (r, op0, op1, 1);
 630
 631     case MULT_EXPR:
 632       return decimal_do_multiply (r, op0, op1);
 633
 634     case RDIV_EXPR:
 635       return decimal_do_divide (r, op0, op1);
 636
 637     case MIN_EXPR:
 638       if (op1->cl == rvc_nan)
 639         *r = *op1;
 640       else if (real_compare (UNLT_EXPR, op0, op1))
 641         *r = *op0;
 642       else
 643         *r = *op1;
 644       return false;
 645
 646     case MAX_EXPR:
 647       if (op1->cl == rvc_nan)
 648         *r = *op1;
 649       else if (real_compare (LT_EXPR, op0, op1))
 650         *r = *op1;
 651       else
 652         *r = *op0;
 653       return false;
 654
 655     case NEGATE_EXPR:
 656       {
 657         decimal128 *d128;
 658         *r = *op0;
 659         d128 = (decimal128 *) r->sig;
 660         /* Flip high bit.  */
 661         d128->bytes[0] ^= 1 << 7;
 662         /* Keep sign field in sync.  */
 663         r->sign ^= 1;
 664       }
 665       return false;
 666
 667     case ABS_EXPR:
 668       {
 669         decimal128 *d128;
 670         *r = *op0;
 671         d128 = (decimal128 *) r->sig;
 672         /* Clear high bit.  */
 673         d128->bytes[0] &= 0x7f;
 674         /* Keep sign field in sync.  */
 675         r->sign = 0;
 676       }
 677       return false;
 678
 679     case FIX_TRUNC_EXPR:
 680       decimal_do_fix_trunc (r, op0);
 681       return false;
 682
 683     default:
 684       gcc_unreachable ();
 685     }
 686 }
 687
 688 /* Fills R with the largest finite value representable in mode MODE.
 689    If SIGN is nonzero, R is set to the most negative finite value.  */
 690
 691 void
 692 decimal_real_maxval (REAL_VALUE_TYPE *r, int sign, enum machine_mode mode)
 693 {
 694   char *max;
 695
 696   switch (mode)
 697     {
 698     case SDmode:
 699       max = (char *) "9.999999E96";
 700       break;
 701     case DDmode:
 702       max = (char *) "9.999999999999999E384";
 703       break;
 704     case TDmode:
 705       max = (char *) "9.999999999999999999999999999999999E6144";
 706       break;
 707     default:
 708       gcc_unreachable ();
 709     }
 710
 711   decimal_real_from_string (r, max);
 712   if (sign)
 713     r->sig[0] |= 0x80000000;
 714 }