misc/efgcvt_r.c

   1 /* [efg]cvt -- compatibility functions for floating point formatting,
   2    reentrent versions.
   3 Copyright (C) 1995, 1996 Free Software Foundation, Inc.
   4 This file is part of the GNU C Library.
   5
   6 The GNU C Library is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU Library General Public License as
   8 published by the Free Software Foundation; either version 2 of the
   9 License, or (at your option) any later version.
  10
  11 The GNU C Library is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with the GNU C Library; see the file COPYING.LIB.  If
  18 not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21 #include <errno.h>
  22 #include <stdio.h>
  23 #include <string.h>
  24 #include <ctype.h>
  25 #include <math.h>
  26 #include <stdlib.h>
  27
  28 int
  29 fcvt_r (value, ndigit, decpt, sign, buf, len)
  30      double value;
  31      int ndigit, *decpt, *sign;
  32      char *buf;
  33      size_t len;
  34 {
  35   int n, i;
  36
  37   if (buf == NULL)
  38     {
  39       errno = EINVAL;
  40       return -1;
  41     }
  42
  43   *sign = value < 0.0;
  44   if (*sign)
  45     value = - value;
  46
  47   n = snprintf (buf, len, "%.*f", ndigit, value);
  48   if (n < 0)
  49     return -1;
  50
  51   i = 0;
  52   while (i < n && isdigit (buf[i]))
  53     ++i;
  54   *decpt = i;
  55   do
  56     ++i;
  57   while (! isdigit (buf[i]));
  58   memmove (&buf[i - *decpt], buf, n - (i - *decpt));
  59
  60   return 0;
  61 }
  62
  63 weak_extern (floor) weak_extern (log10) weak_extern (fabs)
  64
  65 int
  66 ecvt_r (value, ndigit, decpt, sign, buf, len)
  67      double value;
  68      int ndigit, *decpt, *sign;
  69      char *buf;
  70      size_t len;
  71 {
  72   double (*log10_function) (double) = &log10;
  73
  74   if (log10_function)
  75     {
  76       /* Use the reasonable code if -lm is included.  */
  77       ndigit -= (int) floor (log10 (fabs (value)));
  78       if (ndigit < 0)
  79         ndigit = 0;
  80     }
  81   else
  82     {
  83       /* Slow code that doesn't require -lm functions.  */
  84       double d;
  85       for (d = value < 0.0 ? - value : value;
  86            ndigit > 0 && d >= 10.0;
  87            d *= 0.1)
  88         --ndigit;
  89     }
  90
  91   return fcvt_r (value, ndigit, decpt, sign, buf, len);
  92 }