compiler/clib/strtod.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     ANSI C function strtod().
   6 */
   7
   8 #ifndef AROS_NOFPU
   9
  10 #include <ctype.h>
  11 #include <errno.h>
  12 #include <limits.h>
  13
  14 /*****************************************************************************
  15
  16     NAME */
  17 #include <stdlib.h>
  18 #include <math.h>
  19
  20         double strtod (
  21
  22 /*  SYNOPSIS */
  23         const char * str,
  24         char      ** endptr)
  25
  26 /*  FUNCTION
  27         Convert a string of digits into a double.
  28
  29     INPUTS
  30         str - The string which should be converted. Leading
  31                 whitespace are ignored. The number may be prefixed
  32                 by a '+' or '-'. An 'e' or 'E' introduces the exponent.
  33                 Komma is only allowed before exponent.
  34         endptr - If this is non-NULL, then the address of the first
  35                 character after the number in the string is stored
  36                 here.
  37
  38     RESULT
  39         The value of the string. The first character after the number
  40         is returned in *endptr, if endptr is non-NULL. If no digits can
  41         be converted, *endptr contains str (if non-NULL) and 0 is
  42         returned.
  43
  44     NOTES
  45
  46     EXAMPLE
  47
  48     BUGS
  49         NAN is not handled at the moment
  50
  51     SEE ALSO
  52         atof(), atoi(), atol(), strtol(), strtoul()
  53
  54     INTERNALS
  55
  56 ******************************************************************************/
  57 {
  58 #warning TODO: implement NAN handling
  59     double        val = 0, precision;
  60     int           exp = 0;
  61     char          c = 0, c2 = 0;
  62
  63     /* skip all leading spaces */
  64     while (isspace (*str))
  65         str ++;
  66
  67     /* start with scanning the floting point number */
  68     if (*str)
  69     {
  70         /* Is there a sign? */
  71         if (*str == '+' || *str == '-')
  72             c = *str ++;
  73
  74         /* scan numbers before the dot */
  75         while (isdigit(*str))
  76         {
  77             val = val * 10 + (*str - '0');
  78             str ++;
  79         }
  80
  81         /* see if there is the dot */
  82         if(*str == '.')
  83         {
  84             str++;
  85             /* scan the numbers behind the dot */
  86             precision = 0.1;
  87             while (isdigit (*str))
  88             {
  89                 val += ((*str - '0') * precision) ;
  90                 str ++;
  91                 precision = precision * 0.1;
  92             }
  93         }
  94
  95         /* look for a sequence like "E+10" or "e-22" */
  96         if(tolower(*str) == 'e')
  97         {
  98             str++;
  99
 100             if (*str == '+' || *str == '-')
 101                 c2 = *str ++;
 102
 103             while (isdigit (*str))
 104             {
 105                 exp = exp * 10 + (*str - '0');
 106                 str ++;
 107             }
 108             if (c2 == '-')
 109                 exp = -exp;
 110             val *= pow (10, exp);
 111         }
 112
 113         if (c == '-')
 114             val = -val;
 115     }
 116
 117     if (endptr)
 118         *endptr = (char *)str;
 119
 120     return val;
 121 } /* strtod */
 122
 123 #else
 124
 125 void strtod (const char * str,char ** endptr)
 126 {
 127         return;
 128 }
 129
 130 #endif /* AROS_NOFPU */