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#include "strtoull.h"
#include <ctype.h>
#include <limits.h>
#include <errno.h>
#ifdef __GNUC__
union __constcast {
const char *cstr;
char *str;
};
#define CHAR_CONST_CAST( X ) (__extension__(union __constcast)( X )).str
#else
#define CHAR_CONST_CAST( X ) X
#endif
uint64_t __strtoull(const char *nptr, char **endptr, int base)
{
const char *s = nptr;
unsigned long acc;
int c;
unsigned long cutoff;
int neg = 0, any, cutlim;
/*
* See strtol for comments as to the logic used.
*/
do {
c = *s++;
} while (isspace(c));
if (c == '-')
{
neg = 1;
c = *s++;
}
else if (c == '+')
c = *s++;
if ((base == 0 || base == 16) &&
c == '0' && (*s == 'x' || *s == 'X'))
{
c = s[1];
s += 2;
base = 16;
}
if (base == 0)
base = c == '0' ? 8 : 10;
cutoff = (unsigned long)ULONG_MAX / base;
cutlim = (unsigned long)ULONG_MAX % base;
for (acc = 0, any = 0;; c = *s++)
{
if (isdigit(c))
c -= '0';
else if (isalpha(c))
c -= isupper(c) ? 'A' - 10 : 'a' - 10;
else
break;
if (c >= base)
break;
if (any < 0 || acc > cutoff || (acc == cutoff && c > cutlim))
any = -1;
else {
any = 1;
acc *= base;
acc += c;
}
}
if (any < 0)
{
acc = ULONG_MAX;
errno = ERANGE;
}
else if (neg)
acc = -acc;
if (endptr != 0)
*endptr = any ? CHAR_CONST_CAST(s) - 1 : CHAR_CONST_CAST(nptr);
return acc;
}
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