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
  50     SEE ALSO
  51         atof(), atoi(), atol(), strtol(), strtoul()
  52
  53     INTERNALS
  54
  55 ******************************************************************************/
  56 {
  57     double        val = 0, precision;
  58     int           exp = 0;
  59     char          c = 0, c2 = 0;
  60
  61     /* skip all leading spaces */
  62     while (isspace (*str))
  63         str ++;
  64
  65     /* start with scanning the floting point number */
  66     if (*str)
  67     {
  68         /* Is there a sign? */
  69         if (*str == '+' || *str == '-')
  70             c = *str ++;
  71
  72         /* scan numbers before the dot */
  73         while (isdigit(*str))
  74         {
  75             val = val * 10 + (*str - '0');
  76             str ++;
  77         }
  78
  79         /* see if there is the dot */
  80         if(*str == '.')
  81         {
  82             str++;
  83             /* scan the numbers behind the dot */
  84             precision = 0.1;
  85             while (isdigit (*str))
  86             {
  87                 val += ((*str - '0') * precision) ;
  88                 str ++;
  89                 precision = precision * 0.1;
  90             }
  91         }
  92
  93         /* look for a sequence like "E+10" or "e-22" */
  94         if(tolower(*str) == 'e')
  95         {
  96             str++;
  97
  98             if (*str == '+' || *str == '-')
  99                 c2 = *str ++;
 100
 101             while (isdigit (*str))
 102             {
 103                 exp = exp * 10 + (*str - '0');
 104                 str ++;
 105             }
 106             if (c2 == '-')
 107                 exp = -exp;
 108             val *= pow (10, exp);
 109         }
 110
 111         if (c == '-')
 112             val = -val;
 113     }
 114
 115     if (endptr)
 116         *endptr = (char *)str;
 117
 118     return val;
 119 } /* strtod */
 120
 121 #else
 122
 123 void strtod (const char * str,char ** endptr)
 124 {
 125         return;
 126 }
 127
 128 #endif /* AROS_NOFPU */