1  /* Macros for the implementation of *cvt functions, double version.
       2     Copyright (C) 1995-2023 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