misc/efgcvt_r.c

   1 /* [efg]cvt -- compatibility functions for floating point formatting,
   2    reentrant 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 #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
  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       errno = EINVAL;
  55       return -1;
  56     }
  57
  58   *sign = value < 0.0;
  59   if (*sign)
  60     value = - value;
  61
  62   n = snprintf (buf, len, "%.*" FLOAT_FMT_FLAG "f", ndigit, value);
  63   if (n < 0)
  64     return -1;
  65
  66   i = 0;
  67   while (i < n && isdigit (buf[i]))
  68     ++i;
  69   *decpt = i;
  70   do
  71     ++i;
  72   while (! isdigit (buf[i]));
  73   memmove (&buf[i - *decpt], buf, n - (i - *decpt));
  74
  75   return 0;
  76 }
  77
  78 #define weak_extern2(name) weak_extern (name)
  79 weak_extern2 (FLOOR) weak_extern2 (LOG10) weak_extern2 (FABS)
  80
  81 int
  82 APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign, buf, len)
  83      FLOAT_TYPE value;
  84      int ndigit, *decpt, *sign;
  85      char *buf;
  86      size_t len;
  87 {
  88   FLOAT_TYPE (*log10_function) (FLOAT_TYPE) = &LOG10;
  89
  90   if (log10_function)
  91     {
  92       /* Use the reasonable code if -lm is included.  */
  93       ndigit -= (int) FLOOR (LOG10 (FABS (value)));
  94       if (ndigit < 0)
  95         ndigit = 0;
  96     }
  97   else
  98     {
  99       /* Slow code that doesn't require -lm functions.  */
 100       FLOAT_TYPE d;
 101       for (d = value < 0.0 ? - value : value;
 102            ndigit > 0 && d >= 10.0;
 103            d *= 0.1)
 104         --ndigit;
 105     }
 106
 107   return APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign, buf, len);
 108 }