misc/efgcvt_r.c

   1 /* Compatibility functions for floating point formatting, reentrant versions.
   2    Copyright (C) 1995, 1996, 1997 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
  65   n = snprintf (buf, len, "%.*" FLOAT_FMT_FLAG "f", ndigit, value);
  66   if (n < 0)
  67     return -1;
  68
  69   i = 0;
  70   while (i < n && isdigit (buf[i]))
  71     ++i;
  72   *decpt = i;
  73
  74   if (i == 0)
  75     {
  76       /* Value is Inf or NaN.  */
  77       *sign = 0;
  78       return 0;
  79     }
  80
  81   if (i < n)
  82     {
  83       do
  84         ++i;
  85       while (i < n && !isdigit (buf[i]));
  86       memmove (&buf[*decpt], &buf[i], n - i);
  87       buf[n - (i - *decpt)] = 0;
  88     }
  89
  90   return 0;
  91 }
  92
  93 #define weak_extern2(name) weak_extern (name)
  94 weak_extern2 (FLOOR) weak_extern2 (LOG10) weak_extern2 (FABS)
  95 weak_extern2 (EXP)
  96
  97 int
  98 APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign, buf, len)
  99      FLOAT_TYPE value;
 100      int ndigit, *decpt, *sign;
 101      char *buf;
 102      size_t len;
 103 {
 104   int exponent = 0;
 105
 106   if (isfinite (value) && value != 0.0)
 107     {
 108       FLOAT_TYPE (*log10_function) (FLOAT_TYPE) = &LOG10;
 109
 110       if (log10_function)
 111         {
 112           /* Use the reasonable code if -lm is included.  */
 113           FLOAT_TYPE dexponent;
 114           dexponent = FLOOR (LOG10 (FABS (value)));
 115           value *= EXP (dexponent * -M_LN10);
 116           exponent = (int) dexponent;
 117         }
 118       else
 119         {
 120           /* Slow code that doesn't require -lm functions.  */
 121           FLOAT_TYPE d;
 122           if (value < 0.0)
 123             d = -value;
 124           else
 125             d = value;
 126           if (d < 1.0)
 127             {
 128               do
 129                 {
 130                   d *= 10.0;
 131                   exponent--;
 132                 }
 133               while (d < 1.0);
 134             }
 135           else if (d >= 10.0)
 136             {
 137               do
 138                 {
 139                   d *= 0.1;
 140                   exponent++;
 141                 }
 142               while (d >= 10.0);
 143             }
 144           if (value < 0.0)
 145             value = -d;
 146           else
 147             value = d;
 148         }
 149     }
 150
 151   if (APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit - 1, decpt, sign, buf, len))
 152     return -1;
 153   *decpt += exponent;
 154   return 0;
 155 }