sdk/lib/crt/stdlib/fcvtbuf.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <string.h>
   4 #include <float.h>
   5 #include <math.h>
   6 #include <malloc.h>
   7 // #include <msvcrt/locale.h>
   8
   9 // replace fjgpp fcvtbuf from project  http://www.jbox.dk/sanos/source/lib/fcvt.c.html
  10 // with small modification's to match ReactOS arch
  11
  12 // Floating point to string conversion routines
  13 //
  14 // Copyright (C) 2002 Michael Ringgaard. All rights reserved.
  15 //
  16 // Redistribution and use in source and binary forms, with or without
  17 // modification, are permitted provided that the following conditions
  18 // are met:
  19 //
  20 // 1. Redistributions of source code must retain the above copyright
  21 //    notice, this list of conditions and the following disclaimer.
  22 // 2. Redistributions in binary form must reproduce the above copyright
  23 //    notice, this list of conditions and the following disclaimer in the
  24 //    documentation and/or other materials provided with the distribution.
  25 // 3. Neither the name of the project nor the names of its contributors
  26 //    may be used to endorse or promote products derived from this software
  27 //    without specific prior written permission.
  28 //
  29 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
  30 // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  31 // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  32 // ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
  33 // FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  34 // DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  35 // OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  36 // HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  37 // LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  38 // OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  39 // SUCH DAMAGE.
  40 //
  41
  42
  43 //#include <math.h>
  44 #define CVTBUFSIZE  2 * DBL_MAX_10_EXP + 10
  45 static char *cvt(double arg, int ndigits, int *decpt, int *sign, char *buf, int eflag)
  46 {
  47   int r2;
  48   double fi, fj;
  49   char *p, *p1;
  50
  51   if (ndigits >= CVTBUFSIZE - 1) ndigits = CVTBUFSIZE - 2;
  52   r2 = 0;
  53   *sign = 0;
  54   p = &buf[0];
  55   if (arg < 0)
  56   {
  57     *sign = 1;
  58     arg = -arg;
  59   }
  60   arg = modf(arg, &fi);
  61   p1 = &buf[CVTBUFSIZE];
  62
  63   if (fi != 0)
  64   {
  65     p1 = &buf[CVTBUFSIZE];
  66     while (fi != 0)
  67     {
  68       fj = modf(fi / 10, &fi);
  69       *--p1 = (int)((fj + .03) * 10) + '0';
  70       r2++;
  71     }
  72     while (p1 < &buf[CVTBUFSIZE]) *p++ = *p1++;
  73   }
  74   else if (arg > 0)
  75   {
  76     while ((fj = arg * 10) < 1)
  77     {
  78       arg = fj;
  79       r2--;
  80     }
  81   }
  82   p1 = &buf[ndigits];
  83   if (eflag == 0) p1 += r2;
  84   *decpt = r2;
  85   if (p1 < &buf[0])
  86   {
  87     buf[0] = '\0';
  88     return buf;
  89   }
  90   while (p <= p1 && p < &buf[CVTBUFSIZE])
  91   {
  92     arg *= 10;
  93     arg = modf(arg, &fj);
  94     *p++ = (int) fj + '0';
  95   }
  96   if (p1 >= &buf[CVTBUFSIZE])
  97   {
  98     buf[CVTBUFSIZE - 1] = '\0';
  99     return buf;
 100   }
 101   p = p1;
 102   *p1 += 5;
 103   while (*p1 > '9')
 104   {
 105     *p1 = '0';
 106     if (p1 > buf)
 107       ++*--p1;
 108     else
 109     {
 110       *p1 = '1';
 111       (*decpt)++;
 112       if (eflag == 0)
 113       {
 114         if (p > buf) *p = '0';
 115         p++;
 116       }
 117     }
 118   }
 119   *p = '\0';
 120   return buf;
 121 }
 122
 123 char *fcvtbuf(double arg, int ndigits, int *decpt, int *sign, char *buf)
 124 {
 125   return cvt(arg, ndigits, decpt, sign, buf, 0);
 126 }