compiler/clib/strtoul.c

   1 /*
   2     Copyright © 1995-2001, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     ANSI C function strtoul().
   6 */
   7
   8 #include <ctype.h>
   9 #include <errno.h>
  10 #ifndef AROS_NO_LIMITS_H
  11 #       include <limits.h>
  12 #else
  13 #       define ULONG_MAX        4294967295UL
  14 #endif
  15
  16 /*****************************************************************************
  17
  18     NAME */
  19 #include <stdlib.h>
  20
  21         unsigned long strtoul (
  22
  23 /*  SYNOPSIS */
  24         const char * str,
  25         char      ** endptr,
  26         int          base)
  27
  28 /*  FUNCTION
  29         Convert a string of digits into an integer according to the
  30         given base.
  31
  32     INPUTS
  33         str - The string which should be converted. Leading
  34                 whitespace are ignored. The number may be prefixed
  35                 by a '+' or '-'. If base is above 10, then the
  36                 alphabetic characters from 'A' are used to specify
  37                 digits above 9 (ie. 'A' or 'a' is 10, 'B' or 'b' is
  38                 11 and so on until 'Z' or 'z' is 35).
  39         endptr - If this is non-NULL, then the address of the first
  40                 character after the number in the string is stored
  41                 here.
  42         base - The base for the number. May be 0 or between 2 and 36,
  43                 including both. 0 means to autodetect the base. strtoul()
  44                 selects the base by inspecting the first characters
  45                 of the string. If they are "0x", then base 16 is
  46                 assumed. If they are "0", then base 8 is assumed. Any
  47                 other digit will assume base 10. This is like in C.
  48
  49                 If you give base 16, then an optional "0x" may
  50                 precede the number in the string.
  51
  52     RESULT
  53         The value of the string. The first character after the number
  54         is returned in *endptr, if endptr is non-NULL. If no digits can
  55         be converted, *endptr contains str (if non-NULL) and 0 is
  56         returned.
  57
  58     NOTES
  59
  60     EXAMPLE
  61         // Returns 1, ptr points to the 0-Byte
  62         strtoul ("  \t +0x1", &ptr, 0);
  63
  64         // Returns 15. ptr points to the a
  65         strtoul ("017a", &ptr, 0);
  66
  67         // Returns 215 (5*36 + 35)
  68         strtoul ("5z", &ptr, 36);
  69
  70     BUGS
  71
  72     SEE ALSO
  73         atoi(), atol(), strtod(), strtol(), strtoul()
  74
  75     INTERNALS
  76
  77 ******************************************************************************/
  78 {
  79     unsigned long   val   = 0;
  80     int             digit;
  81     char            c = 0;
  82     unsigned long   cutoff;
  83     int             cutlim;
  84     int             any;
  85
  86     if (base < 0 || base == 1 || base > 36)
  87     {
  88         errno = EINVAL;
  89
  90         if (endptr)
  91             *endptr = (char *)str;
  92
  93         return 0;
  94     }
  95
  96     while (isspace (*str))
  97         str ++;
  98
  99
 100     if (*str)
 101     {
 102         if (*str == '+' || *str == '-')
 103             c = *str ++;
 104
 105         /* Assume base ? */
 106         if (base == 0)
 107         {
 108             if (*str == '0') /* Base 8 or 16 */
 109             {
 110                 str++;
 111                 if (*str == 'x' || *str == 'X')
 112                 {
 113                     str++;
 114                     base = 16;
 115                 }
 116                 else
 117                     base = 8;
 118             }
 119             else /* Any other digit: Base 10 (decimal) */
 120                 base = 10;
 121         }
 122
 123         /*
 124             Conversion loop, from FreeBSD's src/lib/libc/stdlib/strtoul.c
 125
 126             The previous AROS loop was
 127             a) inefficient - it did a division each time around.
 128             b) buggy - it returned the wrong value in endptr on overflow.
 129         */
 130         cutoff = (unsigned long)ULONG_MAX / (unsigned long)base;
 131         cutlim = (unsigned long)ULONG_MAX % (unsigned long)base;
 132         val = 0;
 133         any = 0;
 134
 135         while (*str)
 136         {
 137             digit = *str;
 138
 139             if (!isascii(digit))
 140                 break;
 141
 142             if (isdigit(digit))
 143             {
 144                 digit -= '0';
 145             }
 146             else if (isalpha(digit))
 147             {
 148                 digit -= isupper(digit) ? 'A' - 10 : 'a' - 10;
 149             }
 150             else
 151                 break;
 152
 153             if (digit >= base)
 154                 break;
 155
 156             /*
 157                 any < 0 when we have overflowed. We still need to find the
 158                 end of the subject sequence
 159             */
 160             if (any < 0 || val > cutoff || (val == cutoff && digit > cutlim))
 161             {
 162                 any = -1;
 163             }
 164             else
 165             {
 166                 any = 1;
 167                 val = (val * base) + digit;
 168             }
 169
 170             str++;
 171         }
 172
 173         /* Range overflow */
 174         if (any < 0)
 175         {
 176             val = ULONG_MAX;
 177             errno = ERANGE;
 178         }
 179
 180         if (c == '-')
 181             val = -val;
 182     }
 183
 184     if (endptr)
 185         *endptr = (char *)str;
 186
 187     return val;
 188 } /* strtoul */
 189