gcc/real.h

   1 /* Definitions of floating-point access for GNU compiler.
   2    Copyright (C) 1989, 1991, 1994, 1996, 1997, 1998, 1999,
   3    2000, 2002, 2003, 2004, 2005, 2007, 2008 Free Software 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 #ifndef GCC_REAL_H
  22 #define GCC_REAL_H
  23
  24 #ifndef GENERATOR_FILE
  25 #include <gmp.h>
  26 #include <mpfr.h>
  27 #ifdef HAVE_mpc
  28 #include <mpc.h>
  29 # if MPC_VERSION >= MPC_VERSION_NUM(0,6,1)
  30 #  define HAVE_mpc_pow
  31 # endif
  32 #endif
  33 #endif
  34 #include "machmode.h"
  35
  36 /* An expanded form of the represented number.  */
  37
  38 /* Enumerate the special cases of numbers that we encounter.  */
  39 enum real_value_class {
  40   rvc_zero,
  41   rvc_normal,
  42   rvc_inf,
  43   rvc_nan
  44 };
  45
  46 #define SIGNIFICAND_BITS        (128 + HOST_BITS_PER_LONG)
  47 #define EXP_BITS                (32 - 6)
  48 #define MAX_EXP                 ((1 << (EXP_BITS - 1)) - 1)
  49 #define SIGSZ                   (SIGNIFICAND_BITS / HOST_BITS_PER_LONG)
  50 #define SIG_MSB                 ((unsigned long)1 << (HOST_BITS_PER_LONG - 1))
  51
  52 struct GTY(()) real_value {
  53   /* Use the same underlying type for all bit-fields, so as to make
  54      sure they're packed together, otherwise REAL_VALUE_TYPE_SIZE will
  55      be miscomputed.  */
  56   unsigned int /* ENUM_BITFIELD (real_value_class) */ cl : 2;
  57   unsigned int decimal : 1;
  58   unsigned int sign : 1;
  59   unsigned int signalling : 1;
  60   unsigned int canonical : 1;
  61   unsigned int uexp : EXP_BITS;
  62   unsigned long sig[SIGSZ];
  63 };
  64
  65 #define REAL_EXP(REAL) \
  66   ((int)((REAL)->uexp ^ (unsigned int)(1 << (EXP_BITS - 1))) \
  67    - (1 << (EXP_BITS - 1)))
  68 #define SET_REAL_EXP(REAL, EXP) \
  69   ((REAL)->uexp = ((unsigned int)(EXP) & (unsigned int)((1 << EXP_BITS) - 1)))
  70
  71 /* Various headers condition prototypes on #ifdef REAL_VALUE_TYPE, so it
  72    needs to be a macro.  We do need to continue to have a structure tag
  73    so that other headers can forward declare it.  */
  74 #define REAL_VALUE_TYPE struct real_value
  75
  76 /* We store a REAL_VALUE_TYPE into an rtx, and we do this by putting it in
  77    consecutive "w" slots.  Moreover, we've got to compute the number of "w"
  78    slots at preprocessor time, which means we can't use sizeof.  Guess.  */
  79
  80 #define REAL_VALUE_TYPE_SIZE (SIGNIFICAND_BITS + 32)
  81 #define REAL_WIDTH \
  82   (REAL_VALUE_TYPE_SIZE/HOST_BITS_PER_WIDE_INT \
  83    + (REAL_VALUE_TYPE_SIZE%HOST_BITS_PER_WIDE_INT ? 1 : 0)) /* round up */
  84
  85 /* Verify the guess.  */
  86 extern char test_real_width
  87   [sizeof(REAL_VALUE_TYPE) <= REAL_WIDTH*sizeof(HOST_WIDE_INT) ? 1 : -1];
  88
  89 /* Calculate the format for CONST_DOUBLE.  We need as many slots as
  90    are necessary to overlay a REAL_VALUE_TYPE on them.  This could be
  91    as many as four (32-bit HOST_WIDE_INT, 128-bit REAL_VALUE_TYPE).
  92
  93    A number of places assume that there are always at least two 'w'
  94    slots in a CONST_DOUBLE, so we provide them even if one would suffice.  */
  95
  96 #if REAL_WIDTH == 1
  97 # define CONST_DOUBLE_FORMAT     "ww"
  98 #else
  99 # if REAL_WIDTH == 2
 100 #  define CONST_DOUBLE_FORMAT    "ww"
 101 # else
 102 #  if REAL_WIDTH == 3
 103 #   define CONST_DOUBLE_FORMAT   "www"
 104 #  else
 105 #   if REAL_WIDTH == 4
 106 #    define CONST_DOUBLE_FORMAT  "wwww"
 107 #   else
 108 #    if REAL_WIDTH == 5
 109 #     define CONST_DOUBLE_FORMAT "wwwww"
 110 #    else
 111 #     if REAL_WIDTH == 6
 112 #      define CONST_DOUBLE_FORMAT "wwwwww"
 113 #     else
 114        #error "REAL_WIDTH > 6 not supported"
 115 #     endif
 116 #    endif
 117 #   endif
 118 #  endif
 119 # endif
 120 #endif
 121
 122
 123 /* Describes the properties of the specific target format in use.  */
 124 struct real_format
 125 {
 126   /* Move to and from the target bytes.  */
 127   void (*encode) (const struct real_format *, long *,
 128                   const REAL_VALUE_TYPE *);
 129   void (*decode) (const struct real_format *, REAL_VALUE_TYPE *,
 130                   const long *);
 131
 132   /* The radix of the exponent and digits of the significand.  */
 133   int b;
 134
 135   /* Size of the significand in digits of radix B.  */
 136   int p;
 137
 138   /* Size of the significant of a NaN, in digits of radix B.  */
 139   int pnan;
 140
 141   /* The minimum negative integer, x, such that b**(x-1) is normalized.  */
 142   int emin;
 143
 144   /* The maximum integer, x, such that b**(x-1) is representable.  */
 145   int emax;
 146
 147   /* The bit position of the sign bit, for determining whether a value
 148      is positive/negative, or -1 for a complex encoding.  */
 149   int signbit_ro;
 150
 151   /* The bit position of the sign bit, for changing the sign of a number,
 152      or -1 for a complex encoding.  */
 153   int signbit_rw;
 154
 155   /* Default rounding mode for operations on this format.  */
 156   bool round_towards_zero;
 157   bool has_sign_dependent_rounding;
 158
 159   /* Properties of the format.  */
 160   bool has_nans;
 161   bool has_inf;
 162   bool has_denorm;
 163   bool has_signed_zero;
 164   bool qnan_msb_set;
 165   bool canonical_nan_lsbs_set;
 166 };
 167
 168
 169 /* The target format used for each floating point mode.
 170    Float modes are followed by decimal float modes, with entries for
 171    float modes indexed by (MODE - first float mode), and entries for
 172    decimal float modes indexed by (MODE - first decimal float mode) +
 173    the number of float modes.  */
 174 extern const struct real_format *
 175   real_format_for_mode[MAX_MODE_FLOAT - MIN_MODE_FLOAT + 1
 176                        + MAX_MODE_DECIMAL_FLOAT - MIN_MODE_DECIMAL_FLOAT + 1];
 177
 178 #define REAL_MODE_FORMAT(MODE)                                          \
 179   (real_format_for_mode[DECIMAL_FLOAT_MODE_P (MODE)                     \
 180                         ? (((MODE) - MIN_MODE_DECIMAL_FLOAT)            \
 181                            + (MAX_MODE_FLOAT - MIN_MODE_FLOAT + 1))     \
 182                         : ((MODE) - MIN_MODE_FLOAT)])
 183
 184 #define FLOAT_MODE_FORMAT(MODE) \
 185   (REAL_MODE_FORMAT (SCALAR_FLOAT_MODE_P (MODE)? (MODE) \
 186                                                : GET_MODE_INNER (MODE)))
 187
 188 /* The following macro determines whether the floating point format is
 189    composite, i.e. may contain non-consecutive mantissa bits, in which
 190    case compile-time FP overflow may not model run-time overflow.  */
 191 #define MODE_COMPOSITE_P(MODE) \
 192   (FLOAT_MODE_P (MODE) \
 193    && FLOAT_MODE_FORMAT (MODE)->pnan < FLOAT_MODE_FORMAT (MODE)->p)
 194
 195 /* Accessor macros for format properties.  */
 196 #define MODE_HAS_NANS(MODE) \
 197   (FLOAT_MODE_P (MODE) && FLOAT_MODE_FORMAT (MODE)->has_nans)
 198 #define MODE_HAS_INFINITIES(MODE) \
 199   (FLOAT_MODE_P (MODE) && FLOAT_MODE_FORMAT (MODE)->has_inf)
 200 #define MODE_HAS_SIGNED_ZEROS(MODE) \
 201   (FLOAT_MODE_P (MODE) && FLOAT_MODE_FORMAT (MODE)->has_signed_zero)
 202 #define MODE_HAS_SIGN_DEPENDENT_ROUNDING(MODE) \
 203   (FLOAT_MODE_P (MODE) \
 204    && FLOAT_MODE_FORMAT (MODE)->has_sign_dependent_rounding)
 205
 206
 207 /* Declare functions in real.c.  */
 208
 209 /* Binary or unary arithmetic on tree_code.  */
 210 extern bool real_arithmetic (REAL_VALUE_TYPE *, int, const REAL_VALUE_TYPE *,
 211                              const REAL_VALUE_TYPE *);
 212
 213 /* Compare reals by tree_code.  */
 214 extern bool real_compare (int, const REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
 215
 216 /* Determine whether a floating-point value X is infinite.  */
 217 extern bool real_isinf (const REAL_VALUE_TYPE *);
 218
 219 /* Determine whether a floating-point value X is a NaN.  */
 220 extern bool real_isnan (const REAL_VALUE_TYPE *);
 221
 222 /* Determine whether a floating-point value X is finite.  */
 223 extern bool real_isfinite (const REAL_VALUE_TYPE *);
 224
 225 /* Determine whether a floating-point value X is negative.  */
 226 extern bool real_isneg (const REAL_VALUE_TYPE *);
 227
 228 /* Determine whether a floating-point value X is minus zero.  */
 229 extern bool real_isnegzero (const REAL_VALUE_TYPE *);
 230
 231 /* Compare two floating-point objects for bitwise identity.  */
 232 extern bool real_identical (const REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
 233
 234 /* Extend or truncate to a new mode.  */
 235 extern void real_convert (REAL_VALUE_TYPE *, enum machine_mode,
 236                           const REAL_VALUE_TYPE *);
 237
 238 /* Return true if truncating to NEW is exact.  */
 239 extern bool exact_real_truncate (enum machine_mode, const REAL_VALUE_TYPE *);
 240
 241 /* Render R as a decimal floating point constant.  */
 242 extern void real_to_decimal (char *, const REAL_VALUE_TYPE *, size_t,
 243                              size_t, int);
 244
 245 /* Render R as a decimal floating point constant, rounded so as to be
 246    parsed back to the same value when interpreted in mode MODE.  */
 247 extern void real_to_decimal_for_mode (char *, const REAL_VALUE_TYPE *, size_t,
 248                                       size_t, int, enum machine_mode);
 249
 250 /* Render R as a hexadecimal floating point constant.  */
 251 extern void real_to_hexadecimal (char *, const REAL_VALUE_TYPE *,
 252                                  size_t, size_t, int);
 253
 254 /* Render R as an integer.  */
 255 extern HOST_WIDE_INT real_to_integer (const REAL_VALUE_TYPE *);
 256 extern void real_to_integer2 (HOST_WIDE_INT *, HOST_WIDE_INT *,
 257                               const REAL_VALUE_TYPE *);
 258
 259 /* Initialize R from a decimal or hexadecimal string.  Return -1 if
 260    the value underflows, +1 if overflows, and 0 otherwise.  */
 261 extern int real_from_string (REAL_VALUE_TYPE *, const char *);
 262 /* Wrapper to allow different internal representation for decimal floats. */
 263 extern void real_from_string3 (REAL_VALUE_TYPE *, const char *, enum machine_mode);
 264
 265 /* Initialize R from an integer pair HIGH/LOW.  */
 266 extern void real_from_integer (REAL_VALUE_TYPE *, enum machine_mode,
 267                                unsigned HOST_WIDE_INT, HOST_WIDE_INT, int);
 268
 269 extern long real_to_target_fmt (long *, const REAL_VALUE_TYPE *,
 270                                 const struct real_format *);
 271 extern long real_to_target (long *, const REAL_VALUE_TYPE *, enum machine_mode);
 272
 273 extern void real_from_target_fmt (REAL_VALUE_TYPE *, const long *,
 274                                   const struct real_format *);
 275 extern void real_from_target (REAL_VALUE_TYPE *, const long *,
 276                               enum machine_mode);
 277
 278 extern void real_inf (REAL_VALUE_TYPE *);
 279
 280 extern bool real_nan (REAL_VALUE_TYPE *, const char *, int, enum machine_mode);
 281
 282 extern void real_maxval (REAL_VALUE_TYPE *, int, enum machine_mode);
 283
 284 extern void real_2expN (REAL_VALUE_TYPE *, int, enum machine_mode);
 285
 286 extern unsigned int real_hash (const REAL_VALUE_TYPE *);
 287
 288
 289 /* Target formats defined in real.c.  */
 290 extern const struct real_format ieee_single_format;
 291 extern const struct real_format mips_single_format;
 292 extern const struct real_format motorola_single_format;
 293 extern const struct real_format spu_single_format;
 294 extern const struct real_format ieee_double_format;
 295 extern const struct real_format mips_double_format;
 296 extern const struct real_format motorola_double_format;
 297 extern const struct real_format ieee_extended_motorola_format;
 298 extern const struct real_format ieee_extended_intel_96_format;
 299 extern const struct real_format ieee_extended_intel_96_round_53_format;
 300 extern const struct real_format ieee_extended_intel_128_format;
 301 extern const struct real_format ibm_extended_format;
 302 extern const struct real_format mips_extended_format;
 303 extern const struct real_format ieee_quad_format;
 304 extern const struct real_format mips_quad_format;
 305 extern const struct real_format vax_f_format;
 306 extern const struct real_format vax_d_format;
 307 extern const struct real_format vax_g_format;
 308 extern const struct real_format real_internal_format;
 309 extern const struct real_format decimal_single_format;
 310 extern const struct real_format decimal_double_format;
 311 extern const struct real_format decimal_quad_format;
 312 extern const struct real_format ieee_half_format;
 313 extern const struct real_format arm_half_format;
 314
 315
 316 /* ====================================================================== */
 317 /* Crap.  */
 318
 319 #define REAL_ARITHMETIC(value, code, d1, d2) \
 320   real_arithmetic (&(value), code, &(d1), &(d2))
 321
 322 #define REAL_VALUES_IDENTICAL(x, y)     real_identical (&(x), &(y))
 323 #define REAL_VALUES_EQUAL(x, y)         real_compare (EQ_EXPR, &(x), &(y))
 324 #define REAL_VALUES_LESS(x, y)          real_compare (LT_EXPR, &(x), &(y))
 325
 326 /* Determine whether a floating-point value X is infinite.  */
 327 #define REAL_VALUE_ISINF(x)             real_isinf (&(x))
 328
 329 /* Determine whether a floating-point value X is a NaN.  */
 330 #define REAL_VALUE_ISNAN(x)             real_isnan (&(x))
 331
 332 /* Determine whether a floating-point value X is negative.  */
 333 #define REAL_VALUE_NEGATIVE(x)          real_isneg (&(x))
 334
 335 /* Determine whether a floating-point value X is minus zero.  */
 336 #define REAL_VALUE_MINUS_ZERO(x)        real_isnegzero (&(x))
 337
 338 /* IN is a REAL_VALUE_TYPE.  OUT is an array of longs.  */
 339 #define REAL_VALUE_TO_TARGET_LONG_DOUBLE(IN, OUT)                       \
 340   real_to_target (OUT, &(IN),                                           \
 341                   mode_for_size (LONG_DOUBLE_TYPE_SIZE, MODE_FLOAT, 0))
 342
 343 #define REAL_VALUE_TO_TARGET_DOUBLE(IN, OUT) \
 344   real_to_target (OUT, &(IN), mode_for_size (64, MODE_FLOAT, 0))
 345
 346 /* IN is a REAL_VALUE_TYPE.  OUT is a long.  */
 347 #define REAL_VALUE_TO_TARGET_SINGLE(IN, OUT) \
 348   ((OUT) = real_to_target (NULL, &(IN), mode_for_size (32, MODE_FLOAT, 0)))
 349
 350 #define REAL_VALUE_FROM_INT(r, lo, hi, mode) \
 351   real_from_integer (&(r), mode, lo, hi, 0)
 352
 353 #define REAL_VALUE_FROM_UNSIGNED_INT(r, lo, hi, mode) \
 354   real_from_integer (&(r), mode, lo, hi, 1)
 355
 356 /* Real values to IEEE 754 decimal floats.  */
 357
 358 /* IN is a REAL_VALUE_TYPE.  OUT is an array of longs.  */
 359 #define REAL_VALUE_TO_TARGET_DECIMAL128(IN, OUT) \
 360   real_to_target (OUT, &(IN), mode_for_size (128, MODE_DECIMAL_FLOAT, 0))
 361
 362 #define REAL_VALUE_TO_TARGET_DECIMAL64(IN, OUT) \
 363   real_to_target (OUT, &(IN), mode_for_size (64, MODE_DECIMAL_FLOAT, 0))
 364
 365 /* IN is a REAL_VALUE_TYPE.  OUT is a long.  */
 366 #define REAL_VALUE_TO_TARGET_DECIMAL32(IN, OUT) \
 367   ((OUT) = real_to_target (NULL, &(IN), mode_for_size (32, MODE_DECIMAL_FLOAT, 0)))
 368
 369 extern REAL_VALUE_TYPE real_value_truncate (enum machine_mode,
 370                                             REAL_VALUE_TYPE);
 371
 372 #define REAL_VALUE_TO_INT(plow, phigh, r) \
 373   real_to_integer2 (plow, phigh, &(r))
 374
 375 extern REAL_VALUE_TYPE real_arithmetic2 (int, const REAL_VALUE_TYPE *,
 376                                          const REAL_VALUE_TYPE *);
 377
 378 #define REAL_VALUE_NEGATE(X) \
 379   real_arithmetic2 (NEGATE_EXPR, &(X), NULL)
 380
 381 #define REAL_VALUE_ABS(X) \
 382   real_arithmetic2 (ABS_EXPR, &(X), NULL)
 383
 384 extern int significand_size (enum machine_mode);
 385
 386 extern REAL_VALUE_TYPE real_from_string2 (const char *, enum machine_mode);
 387
 388 #define REAL_VALUE_ATOF(s, m) \
 389   real_from_string2 (s, m)
 390
 391 #define CONST_DOUBLE_ATOF(s, m) \
 392   CONST_DOUBLE_FROM_REAL_VALUE (real_from_string2 (s, m), m)
 393
 394 #define REAL_VALUE_FIX(r) \
 395   real_to_integer (&(r))
 396
 397 /* ??? Not quite right.  */
 398 #define REAL_VALUE_UNSIGNED_FIX(r) \
 399   real_to_integer (&(r))
 400
 401 /* ??? These were added for Paranoia support.  */
 402
 403 /* Return floor log2(R).  */
 404 extern int real_exponent (const REAL_VALUE_TYPE *);
 405
 406 /* R = A * 2**EXP.  */
 407 extern void real_ldexp (REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *, int);
 408
 409 /* **** End of software floating point emulator interface macros **** */
 410 \f
 411 /* Constant real values 0, 1, 2, -1 and 0.5.  */
 412
 413 extern REAL_VALUE_TYPE dconst0;
 414 extern REAL_VALUE_TYPE dconst1;
 415 extern REAL_VALUE_TYPE dconst2;
 416 extern REAL_VALUE_TYPE dconstm1;
 417 extern REAL_VALUE_TYPE dconsthalf;
 418
 419 #define dconst_e()  (*dconst_e_ptr ())
 420 #define dconst_third()  (*dconst_third_ptr ())
 421 #define dconst_sqrt2()  (*dconst_sqrt2_ptr ())
 422
 423 /* Function to return the real value special constant 'e'.  */
 424 extern const REAL_VALUE_TYPE * dconst_e_ptr (void);
 425
 426 /* Returns the special REAL_VALUE_TYPE corresponding to 1/3.  */
 427 extern const REAL_VALUE_TYPE * dconst_third_ptr (void);
 428
 429 /* Returns the special REAL_VALUE_TYPE corresponding to sqrt(2).  */
 430 extern const REAL_VALUE_TYPE * dconst_sqrt2_ptr (void);
 431
 432 /* Function to return a real value (not a tree node)
 433    from a given integer constant.  */
 434 REAL_VALUE_TYPE real_value_from_int_cst (const_tree, const_tree);
 435
 436 /* Given a CONST_DOUBLE in FROM, store into TO the value it represents.  */
 437 #define REAL_VALUE_FROM_CONST_DOUBLE(to, from) \
 438   ((to) = *CONST_DOUBLE_REAL_VALUE (from))
 439
 440 /* Return a CONST_DOUBLE with value R and mode M.  */
 441 #define CONST_DOUBLE_FROM_REAL_VALUE(r, m) \
 442   const_double_from_real_value (r, m)
 443 extern rtx const_double_from_real_value (REAL_VALUE_TYPE, enum machine_mode);
 444
 445 /* Replace R by 1/R in the given machine mode, if the result is exact.  */
 446 extern bool exact_real_inverse (enum machine_mode, REAL_VALUE_TYPE *);
 447
 448 /* Return true if arithmetic on values in IMODE that were promoted
 449    from values in TMODE is equivalent to direct arithmetic on values
 450    in TMODE.  */
 451 bool real_can_shorten_arithmetic (enum machine_mode, enum machine_mode);
 452
 453 /* In tree.c: wrap up a REAL_VALUE_TYPE in a tree node.  */
 454 extern tree build_real (tree, REAL_VALUE_TYPE);
 455
 456 /* Calculate R as the square root of X in the given machine mode.  */
 457 extern bool real_sqrt (REAL_VALUE_TYPE *, enum machine_mode,
 458                        const REAL_VALUE_TYPE *);
 459
 460 /* Calculate R as X raised to the integer exponent N in mode MODE.  */
 461 extern bool real_powi (REAL_VALUE_TYPE *, enum machine_mode,
 462                        const REAL_VALUE_TYPE *, HOST_WIDE_INT);
 463
 464 /* Standard round to integer value functions.  */
 465 extern void real_trunc (REAL_VALUE_TYPE *, enum machine_mode,
 466                         const REAL_VALUE_TYPE *);
 467 extern void real_floor (REAL_VALUE_TYPE *, enum machine_mode,
 468                         const REAL_VALUE_TYPE *);
 469 extern void real_ceil (REAL_VALUE_TYPE *, enum machine_mode,
 470                        const REAL_VALUE_TYPE *);
 471 extern void real_round (REAL_VALUE_TYPE *, enum machine_mode,
 472                         const REAL_VALUE_TYPE *);
 473
 474 /* Set the sign of R to the sign of X.  */
 475 extern void real_copysign (REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
 476
 477 #ifndef GENERATOR_FILE
 478 /* Convert between MPFR and REAL_VALUE_TYPE.  The caller is
 479    responsible for initializing and clearing the MPFR parameter.  */
 480
 481 extern void real_from_mpfr (REAL_VALUE_TYPE *, mpfr_srcptr, tree, mp_rnd_t);
 482 extern void mpfr_from_real (mpfr_ptr, const REAL_VALUE_TYPE *, mp_rnd_t);
 483 #endif
 484
 485 /* Check whether the real constant value given is an integer.  */
 486 extern bool real_isinteger (const REAL_VALUE_TYPE *c, enum machine_mode mode);
 487
 488 /* Write into BUF the maximum representable finite floating-point
 489    number, (1 - b**-p) * b**emax for a given FP format FMT as a hex
 490    float string.  BUF must be large enough to contain the result.  */
 491 extern void get_max_float (const struct real_format *, char *, size_t);
 492 #endif /* ! GCC_REAL_H */