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 #include <sys/param.h>
  27
  28 #ifndef FLOAT_TYPE
  29 #define FLOAT_TYPE double
  30 #define FUNC_PREFIX
  31 #define FLOAT_FMT_FLAG
  32 #define FLOAT_NAME_EXT
  33 #endif
  34
  35 #define APPEND(a, b) APPEND2 (a, b)
  36 #define APPEND2(a, b) a##b
  37
  38 #define FLOOR APPEND(floor, FLOAT_NAME_EXT)
  39 #define FABS APPEND(fabs, FLOAT_NAME_EXT)
  40 #define LOG10 APPEND(log10, FLOAT_NAME_EXT)
  41 #define EXP APPEND(exp, FLOAT_NAME_EXT)
  42
  43
  44 int
  45 APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign, buf, len)
  46      FLOAT_TYPE value;
  47      int ndigit, *decpt, *sign;
  48      char *buf;
  49      size_t len;
  50 {
  51   int n, i;
  52   int left;
  53
  54   if (buf == NULL)
  55     {
  56       __set_errno (EINVAL);
  57       return -1;
  58     }
  59
  60   left = 0;
  61   if (isfinite (value))
  62     {
  63       *sign = signbit (value) != 0;
  64       if (*sign)
  65         value = -value;
  66
  67       if (ndigit < 0)
  68         {
  69           /* Rounding to the left of the decimal point.  */
  70           while (ndigit < 0)
  71             {
  72               FLOAT_TYPE new_value = value * 0.1;
  73
  74               if (new_value < 1.0)
  75                 {
  76                   ndigit = 0;
  77                   break;
  78                 }
  79
  80               value = new_value;
  81               ++left;
  82               ++ndigit;
  83             }
  84         }
  85     }
  86   else
  87     /* Value is Inf or NaN.  */
  88     *sign = 0;
  89
  90   n = __snprintf (buf, len, "%.*" FLOAT_FMT_FLAG "f", ndigit, value);
  91   if (n < 0)
  92     return -1;
  93
  94   i = 0;
  95   while (i < n && isdigit (buf[i]))
  96     ++i;
  97   *decpt = i;
  98
  99   if (i == 0)
 100     /* Value is Inf or NaN.  */
 101     return 0;
 102
 103   if (i < n)
 104     {
 105       do
 106         ++i;
 107       while (i < n && !isdigit (buf[i]));
 108
 109       if (*decpt == 1 && buf[0] == '0' && value != 0.0)
 110         {
 111           /* We must not have leading zeroes.  Strip them all out and
 112              adjust *DECPT if necessary.  */
 113           --*decpt;
 114           while (i < n && buf[i] == '0')
 115             {
 116               --*decpt;
 117               ++i;
 118             }
 119         }
 120
 121       memmove (&buf[MAX (*decpt, 0)], &buf[i], n - i);
 122       buf[n - (i - MAX (*decpt, 0))] = '\0';
 123     }
 124
 125   if (left)
 126     {
 127       *decpt += left;
 128       if (--len > n)
 129         {
 130           while (left-- > 0 && n < len)
 131             buf[n++] = '0';
 132           buf[n] = '\0';
 133         }
 134     }
 135
 136   return 0;
 137 }
 138
 139 int
 140 APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign, buf, len)
 141      FLOAT_TYPE value;
 142      int ndigit, *decpt, *sign;
 143      char *buf;
 144      size_t len;
 145 {
 146   int exponent = 0;
 147
 148   if (isfinite (value) && value != 0.0)
 149     {
 150       /* Slow code that doesn't require -lm functions.  */
 151       FLOAT_TYPE d;
 152       FLOAT_TYPE f = 1.0;
 153       if (value < 0.0)
 154         d = -value;
 155       else
 156         d = value;
 157       if (d < 1.0)
 158         {
 159           do
 160             {
 161               f *= 10.0;
 162               --exponent;
 163             }
 164           while (d * f < 1.0);
 165
 166           value *= f;
 167         }
 168       else if (d >= 10.0)
 169         {
 170           do
 171             {
 172               f *= 10;
 173               ++exponent;
 174             }
 175           while (d >= f * 10.0);
 176
 177           value /= f;
 178         }
 179     }
 180   else if (value == 0.0)
 181     /* SUSv2 leaves it unspecified whether *DECPT is 0 or 1 for 0.0.
 182        This could be changed to -1 if we want to return 0.  */
 183     exponent = 0;
 184
 185   if (ndigit <= 0 && len > 0)
 186     {
 187       buf[0] = '\0';
 188       *decpt = 1;
 189       *sign = isfinite (value) ? signbit (value) != 0 : 0;
 190     }
 191   else
 192     if (APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit - 1, decpt, sign,
 193                                       buf, len))
 194       return -1;
 195
 196   *decpt += exponent;
 197   return 0;
 198 }