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 #define ISINF APPEND(isinf, FLOAT_NAME_EXT)
  42 #define ISNAN APPEND(isnan, FLOAT_NAME_EXT)
  43
  44
  45 int
  46 APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit, decpt, sign, buf, len)
  47      FLOAT_TYPE value;
  48      int ndigit, *decpt, *sign;
  49      char *buf;
  50      size_t len;
  51 {
  52   int n, i;
  53
  54   if (buf == NULL)
  55     {
  56       __set_errno (EINVAL);
  57       return -1;
  58     }
  59
  60   if (!ISINF (value) && !ISNAN (value))
  61     {
  62       /* OK, the following is not entirely correct.  -0.0 is not handled
  63          correctly but glibc 2.0 does not have a portable function to
  64          implement this test.  */
  65       *sign = value < 0.0;
  66       if (*sign)
  67         value = -value;
  68     }
  69
  70   n = snprintf (buf, len, "%.*" FLOAT_FMT_FLAG "f", ndigit, value);
  71   if (n < 0)
  72     return -1;
  73
  74   i = 0;
  75   while (i < n && isdigit (buf[i]))
  76     ++i;
  77   *decpt = i;
  78
  79   if (i == 0)
  80     {
  81       /* Value is Inf or NaN.  */
  82       *sign = 0;
  83       return 0;
  84     }
  85
  86   if (i < n)
  87     {
  88       do
  89         ++i;
  90       while (i < n && !isdigit (buf[i]));
  91       memmove (&buf[*decpt], &buf[i], n - i);
  92       buf[n - (i - *decpt)] = 0;
  93     }
  94
  95   return 0;
  96 }
  97
  98 #define weak_extern2(name) weak_extern (name)
  99 weak_extern2 (FLOOR) weak_extern2 (LOG10) weak_extern2 (FABS)
 100 weak_extern2 (EXP)
 101
 102 int
 103 APPEND (FUNC_PREFIX, ecvt_r) (value, ndigit, decpt, sign, buf, len)
 104      FLOAT_TYPE value;
 105      int ndigit, *decpt, *sign;
 106      char *buf;
 107      size_t len;
 108 {
 109   int exponent = 0;
 110
 111   if (!ISNAN (value) && !ISINF (value) && value != 0.0)
 112     {
 113       FLOAT_TYPE (*log10_function) (FLOAT_TYPE) = &LOG10;
 114
 115       if (log10_function)
 116         {
 117           /* Use the reasonable code if -lm is included.  */
 118           FLOAT_TYPE dexponent;
 119           dexponent = FLOOR (LOG10 (FABS (value)));
 120           value *= EXP (dexponent * -M_LN10);
 121           exponent = (int) dexponent;
 122         }
 123       else
 124         {
 125           /* Slow code that doesn't require -lm functions.  */
 126           FLOAT_TYPE d;
 127           if (value < 0.0)
 128             d = -value;
 129           else
 130             d = value;
 131           if (d < 1.0)
 132             {
 133               do
 134                 {
 135                   d *= 10.0;
 136                   exponent--;
 137                 }
 138               while (d < 1.0);
 139             }
 140           else if (d >= 10.0)
 141             {
 142               do
 143                 {
 144                   d *= 0.1;
 145                   exponent++;
 146                 }
 147               while (d >= 10.0);
 148             }
 149           if (value < 0.0)
 150             value = -d;
 151           else
 152             value = d;
 153         }
 154     }
 155
 156   if (APPEND (FUNC_PREFIX, fcvt_r) (value, ndigit - 1, decpt, sign, buf, len))
 157     return -1;
 158   *decpt += exponent;
 159   return 0;
 160 }