misc/efgcvt_r.c

   1 /* Compatibility functions for floating point formatting, reentrant versions.
   2    Copyright (C) 1995, 1996, 1997, 1998 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 <errno.h>
  21 #include <stdio.h>
  22 #include <string.h>
  23 #include <ctype.h>
  24 #include <math.h>
  25 #include <stdlib.h>
  26
  27 #ifndef FLOAT_TYPE
  28 #define FLOAT_TYPE double
  29 #define FUNC_PREFIX
  30 #define FLOAT_FMT_FLAG
  31 #define FLOAT_NAME_EXT
  32 #endif
  33
  34 #define APPEND(a, b) APPEND2 (a, b)
  35 #define APPEND2(a, b) a##b
  36
  37 #define FLOOR APPEND(floor, FLOAT_NAME_EXT)
  38 #define FABS APPEND(fabs, FLOAT_NAME_EXT)
  39 #define LOG10 APPEND(log10, FLOAT_NAME_EXT)
  40 #define EXP APPEND(exp, FLOAT_NAME_EXT)
  41
  42
  43 int
  44 APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign, buf, len)
  45      FLOAT_TYPE value;
  46      int ndigit, *decpt, *sign;
  47      char *buf;
  48      size_t len;
  49 {
  50   int n, i;
  51
  52   if (buf == NULL)
  53     {
  54       __set_errno (EINVAL);
  55       return -1;
  56     }
  57
  58   if (isfinite (value))
  59     {
  60       *sign = signbit (value) != 0;
  61       if (*sign)
  62         value = -value;
  63     }
  64   else
  65     /* Value is Inf or NaN.  */
  66     *sign = 0;
  67
  68   if (ndigit <= 0)
  69     {
  70       if (len > 0)
  71         buf[0] = '\0';
  72       *decpt = 0;
  73       return 0;
  74     }
  75
  76   n = snprintf (buf, len, "%.*" FLOAT_FMT_FLAG "f", ndigit, value);
  77   if (n < 0)
  78     return -1;
  79
  80   i = 0;
  81   while (i < n && isdigit (buf[i]))
  82     ++i;
  83   *decpt = i;
  84
  85   if (i == 0)
  86     /* Value is Inf or NaN.  */
  87     return 0;
  88
  89   if (i < n)
  90     {
  91       do
  92         ++i;
  93       while (i < n && !isdigit (buf[i]));
  94       memmove (&buf[*decpt], &buf[i], n - i);
  95       buf[n - (i - *decpt)] = '\0';
  96     }
  97
  98   return 0;
  99 }
 100
 101 #define weak_extern2(name) weak_extern (name)
 102 weak_extern2 (FLOOR) weak_extern2 (LOG10) weak_extern2 (FABS)
 103 weak_extern2 (EXP)
 104
 105 int
 106 APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign, buf, len)
 107      FLOAT_TYPE value;
 108      int ndigit, *decpt, *sign;
 109      char *buf;
 110      size_t len;
 111 {
 112   int exponent = 0;
 113
 114   if (isfinite (value) && value != 0.0)
 115     {
 116       FLOAT_TYPE (*log10_function) (FLOAT_TYPE) = &LOG10;
 117
 118       if (log10_function)
 119         {
 120           /* Use the reasonable code if -lm is included.  */
 121           FLOAT_TYPE dexponent;
 122           dexponent = FLOOR (LOG10 (FABS (value)));
 123           value *= EXP (dexponent * -M_LN10);
 124           exponent = (int) dexponent;
 125         }
 126       else
 127         {
 128           /* Slow code that doesn't require -lm functions.  */
 129           FLOAT_TYPE d;
 130           if (value < 0.0)
 131             d = -value;
 132           else
 133             d = value;
 134           if (d < 1.0)
 135             {
 136               do
 137                 {
 138                   d *= 10.0;
 139                   exponent--;
 140                 }
 141               while (d < 1.0);
 142             }
 143           else if (d >= 10.0)
 144             {
 145               do
 146                 {
 147                   d *= 0.1;
 148                   exponent++;
 149                 }
 150               while (d >= 10.0);
 151             }
 152           if (value < 0.0)
 153             value = -d;
 154           else
 155             value = d;
 156         }
 157     }
 158
 159   if (APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit - 1, decpt, sign, buf, len))
 160     return -1;
 161   *decpt += exponent;
 162   return 0;
 163 }