reactos/sdk/lib/crt/string/wcstol.c

99 lines
2.5 KiB
C

/*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS system libraries
* FILE: lib/sdk/crt/string/wcstol.c
* PURPOSE: Unknown
* PROGRAMER: Unknown
* UPDATE HISTORY:
* 25/11/05: Added license header
*/
#include <precomp.h>
/*
* @implemented
*/
long
CDECL
wcstol(const wchar_t *nptr, wchar_t **endptr, int base)
{
const wchar_t *s = nptr;
long acc;
int c;
unsigned long cutoff;
int neg = 0, any, cutlim;
/*
* Skip white space and pick up leading +/- sign if any.
* If base is 0, allow 0x for hex and 0 for octal, else
* assume decimal; if base is already 16, allow 0x.
*/
do {
c = *s++;
} while (iswctype(c, _SPACE));
if (c == '-')
{
neg = 1;
c = *s++;
}
else if (c == L'+')
c = *s++;
if ((base == 0 || base == 16) &&
c == L'0' && (*s == L'x' || *s == L'X'))
{
c = s[1];
s += 2;
base = 16;
}
if (base == 0)
base = c == L'0' ? 8 : 10;
/*
* Compute the cutoff value between legal numbers and illegal
* numbers. That is the largest legal value, divided by the
* base. An input number that is greater than this value, if
* followed by a legal input character, is too big. One that
* is equal to this value may be valid or not; the limit
* between valid and invalid numbers is then based on the last
* digit. For instance, if the range for longs is
* [-2147483648..2147483647] and the input base is 10,
* cutoff will be set to 214748364 and cutlim to either
* 7 (neg==0) or 8 (neg==1), meaning that if we have accumulated
* a value > 214748364, or equal but the next digit is > 7 (or 8),
* the number is too big, and we will return a range error.
*
* Set any if any `digits' consumed; make it negative to indicate
* overflow.
*/
cutoff = neg ? ((unsigned long)LONG_MAX+1) : LONG_MAX;
cutlim = cutoff % (unsigned long)base;
cutoff /= (unsigned long)base;
for (acc = 0, any = 0;; c = *s++)
{
if (iswctype(c, _DIGIT))
c -= L'0';
else if (iswctype(c, _ALPHA))
c -= iswctype(c, _UPPER) ? L'A' - 10 : L'a' - 10;
else
break;
if (c >= base)
break;
if (any < 0 || (unsigned long)acc > cutoff || (acc == cutoff && c > cutlim))
any = -1;
else
{
any = 1;
acc *= base;
acc += c;
}
}
if (any < 0)
{
acc = neg ? LONG_MIN : LONG_MAX;
}
else if (neg)
acc = 0-acc;
if (endptr != 0)
*endptr = any ? (wchar_t *)((size_t)(s - 1)) : (wchar_t *)((size_t)nptr);
return acc;
}