reactos/lib/crtdll/stdlib/fcvtbuf.c

   1 /* Copyright (C) 1998 DJ Delorie, see COPYING.DJ for details */
   2 #include <msvcrt/stdlib.h>
   3 #include <msvcrt/stdio.h>
   4 #include <msvcrt/string.h>
   5 #include <msvcrt/float.h>
   6 #include <msvcrt/alloc.h>
   7 // #include <msvcrt/locale.h>
   8
   9 void __ecvround (char *, char *, const char *, int *);
  10 char *ecvtbuf (double, int, int *, int *, char *);
  11
  12 char *
  13 fcvtbuf (double value, int ndigits, int *decpt, int *sign, char *buf)
  14 {
  15   static char INFINITY[] = "Infinity";
  16   char decimal = '.' /* localeconv()->decimal_point[0] */;
  17   int digits = ndigits >= 0 ? ndigits : 0;
  18   char *cvtbuf = (char *)alloca (2*DBL_MAX_10_EXP + 16);
  19   char *s = cvtbuf;
  20   char *dot;
  21
  22   sprintf (cvtbuf, "%-+#.*f", DBL_MAX_10_EXP + digits + 1, value);
  23
  24   /* The sign.  */
  25   if (*s++ == '-')
  26     *sign = 1;
  27   else
  28     *sign = 0;
  29
  30   /* Where's the decimal point?  */
  31   dot = strchr (s, decimal);
  32   *decpt = dot ? dot - s : strlen (s);
  33
  34   /* SunOS docs says if NDIGITS is 8 or more, produce "Infinity"
  35      instead of "Inf".  */
  36   if (strncmp (s, "Inf", 3) == 0)
  37     {
  38       memcpy (buf, INFINITY, ndigits >= 8 ? 9 : 3);
  39       if (ndigits < 8)
  40         buf[3] = '\0';
  41       return buf;
  42     }
  43   else if (ndigits < 0)
  44     return ecvtbuf (value, *decpt + ndigits, decpt, sign, buf);
  45   else if (*s == '0' && value != 0.0)
  46     return ecvtbuf (value, ndigits, decpt, sign, buf);
  47   else
  48     {
  49       memcpy (buf, s, *decpt);
  50       if (s[*decpt] == decimal)
  51         {
  52           memcpy (buf + *decpt, s + *decpt + 1, ndigits);
  53           buf[*decpt + ndigits] = '\0';
  54         }
  55       else
  56         buf[*decpt] = '\0';
  57       __ecvround (buf, buf + *decpt + ndigits - 1,
  58                 s + *decpt + ndigits + 1, decpt);
  59       return buf;
  60     }
  61 }