misc/efgcvt-dbl-macros.h

   1 /* Macros for the implementation of *cvt functions, double version.
   2    Copyright (C) 1995-2024 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <float.h>
  20
  21 #define FLOAT_TYPE double
  22 #define FUNC_PREFIX
  23 #define FLOAT_FMT_FLAG
  24 #define FLOAT_NAME_EXT
  25 #define FLOAT_MIN_10_EXP DBL_MIN_10_EXP
  26 /* Actually we have to write (DBL_DIG + log10 (DBL_MAX_10_EXP)) but we
  27    don't have log10 available in the preprocessor.  */
  28 #define MAXDIG (NDIGIT_MAX + 3)
  29 #define FCVT_MAXDIG (DBL_MAX_10_EXP + MAXDIG)
  30 #if DBL_MANT_DIG == 53
  31 # define NDIGIT_MAX 17
  32 #elif DBL_MANT_DIG == 24
  33 # define NDIGIT_MAX 9
  34 #elif DBL_MANT_DIG == 56
  35 # define NDIGIT_MAX 18
  36 #else
  37 /* See IEEE 854 5.6, table 2 for this formula.  Unfortunately we need a
  38    compile time constant here, so we cannot use it.  */
  39 # error "NDIGIT_MAX must be precomputed"
  40 # define NDIGIT_MAX (lrint (ceil (M_LN2 / M_LN10 * DBL_MANT_DIG + 1.0)))
  41 #endif
  42 #if DBL_MIN_10_EXP == -37
  43 # define FLOAT_MIN_10_NORM      1.0e-37
  44 #elif DBL_MIN_10_EXP == -307
  45 # define FLOAT_MIN_10_NORM      1.0e-307
  46 #elif DBL_MIN_10_EXP == -4931
  47 # define FLOAT_MIN_10_NORM      1.0e-4931
  48 #else
  49 /* libc can't depend on libm.  */
  50 # error "FLOAT_MIN_10_NORM must be precomputed"
  51 # define FLOAT_MIN_10_NORM      exp10 (DBL_MIN_10_EXP)
  52 #endif