reactos/lib/string/wcstoul.c

   1 #include <string.h>
   2 #include <ctype.h>
   3 #include <limits.h>
   4
   5
   6 /*
   7  * Convert a unicode string to an unsigned long integer.
   8  *
   9  * Ignores `locale' stuff.  Assumes that the upper and lower case
  10  * alphabets and digits are each contiguous.
  11  *
  12  * @implemented
  13  */
  14 unsigned long
  15 wcstoul(const wchar_t *nptr, wchar_t **endptr, int base)
  16 {
  17   const wchar_t *s = nptr;
  18   unsigned long acc;
  19   int c;
  20   unsigned long cutoff;
  21   int neg = 0, any, cutlim;
  22
  23   /*
  24    * See strtol for comments as to the logic used.
  25    */
  26   do {
  27     c = *s++;
  28   } while (iswctype(c, _SPACE));
  29   if (c == '-')
  30   {
  31     neg = 1;
  32     c = *s++;
  33   }
  34   else if (c == L'+')
  35     c = *s++;
  36   if ((base == 0 || base == 16) &&
  37       c == L'0' && (*s == L'x' || *s == L'X'))
  38   {
  39     c = s[1];
  40     s += 2;
  41     base = 16;
  42   }
  43   if (base == 0)
  44     base = c == L'0' ? 8 : 10;
  45   cutoff = (unsigned long)ULONG_MAX / (unsigned long)base;
  46   cutlim = (unsigned long)ULONG_MAX % (unsigned long)base;
  47   for (acc = 0, any = 0;; c = *s++)
  48   {
  49     if (iswctype(c, _DIGIT))
  50       c -= L'0';
  51     else if (iswctype(c, _ALPHA))
  52       c -= iswctype(c, _UPPER) ? L'A' - 10 : L'a' - 10;
  53     else
  54       break;
  55     if (c >= base)
  56       break;
  57     if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
  58       any = -1;
  59     else {
  60       any = 1;
  61       acc *= base;
  62       acc += c;
  63     }
  64   }
  65   if (any < 0)
  66   {
  67     acc = ULONG_MAX;
  68   }
  69   else if (neg)
  70     acc = -acc;
  71   if (endptr != 0)
  72     *endptr = any ? (wchar_t *)s - 1 : (wchar_t *)nptr;
  73   return acc;
  74 }