misc/efgcvt.c

   1 /* Compatibility functions for floating point formatting.
   2    Copyright (C) 1995, 1996, 1997, 1999 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <math.h>
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <sys/param.h>
  24 #include <float.h>
  25 #include <bits/libc-lock.h>
  26
  27 #ifndef FLOAT_TYPE
  28 # define FLOAT_TYPE double
  29 # define FUNC_PREFIX
  30 # define FLOAT_FMT_FLAG
  31 /* Actually we have to write (DBL_DIG + log10 (DBL_MAX_10_EXP)) but we
  32    don't have log10 available in the preprocessor.  */
  33 # define MAXDIG (NDIGIT_MAX + 3)
  34 # if DBL_MANT_DIG == 53
  35 #  define NDIGIT_MAX 17
  36 # elif DBL_MANT_DIG == 24
  37 #  define NDIGIT_MAX 9
  38 # elif DBL_MANT_DIG == 56
  39 #  define NDIGIT_MAX 18
  40 # else
  41 /* See IEEE 854 5.6, table 2 for this formula.  Unfortunately we need a
  42    compile time constant here, so we cannot use it.  */
  43 #  error "NDIGIT_MAX must be precomputed"
  44 #  define NDIGIT_MAX (lrint (ceil (M_LN2 / M_LN10 * DBL_MANT_DIG + 1.0)))
  45 # endif
  46 #endif
  47
  48 #define APPEND(a, b) APPEND2 (a, b)
  49 #define APPEND2(a, b) a##b
  50
  51
  52 #define FCVT_BUFFER APPEND (FUNC_PREFIX, fcvt_buffer)
  53 #define ECVT_BUFFER APPEND (FUNC_PREFIX, ecvt_buffer)
  54
  55
  56 static char FCVT_BUFFER[MAXDIG];
  57 static char ECVT_BUFFER[MAXDIG];
  58
  59
  60 char *
  61 APPEND (FUNC_PREFIX, fcvt) (value, ndigit, decpt, sign)
  62      FLOAT_TYPE value;
  63      int ndigit, *decpt, *sign;
  64 {
  65   (void) APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign,
  66                                        FCVT_BUFFER, MAXDIG);
  67
  68   return FCVT_BUFFER;
  69 }
  70
  71
  72 char *
  73 APPEND (FUNC_PREFIX, ecvt) (value, ndigit, decpt, sign)
  74      FLOAT_TYPE value;
  75      int ndigit, *decpt, *sign;
  76 {
  77   (void) APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign,
  78                                        ECVT_BUFFER, MAXDIG);
  79
  80   return ECVT_BUFFER;
  81 }
  82
  83 char *
  84 APPEND (FUNC_PREFIX, gcvt) (value, ndigit, buf)
  85      FLOAT_TYPE value;
  86      int ndigit;
  87      char *buf;
  88 {
  89   sprintf (buf, "%.*" FLOAT_FMT_FLAG "g", MIN (ndigit, NDIGIT_MAX), value);
  90   return buf;
  91 }