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- #include <errno.h>
- #include <limits.h>
- #include <stddef.h>
- #include <stdlib.h>
- unsigned long long strtoull(const char *nptr, char **endptr, int base)
- {
- const char *s;
- unsigned long long acc;
- char c;
- unsigned long long cutoff;
- int neg, any, cutlim;
-
- s = nptr;
- do {
- c = *s++;
- } while (isspace((unsigned char)c));
- if (c == '-') {
- neg = 1;
- c = *s++;
- } else {
- neg = 0;
- if (c == '+')
- c = *s++;
- }
- if ((base == 0 || base == 16) &&
- c == '0' && (*s == 'x' || *s == 'X') &&
- ((s[1] >= '0' && s[1] <= '9') ||
- (s[1] >= 'A' && s[1] <= 'F') ||
- (s[1] >= 'a' && s[1] <= 'f'))) {
- c = s[1];
- s += 2;
- base = 16;
- }
- if (base == 0)
- base = c == '0' ? 8 : 10;
- acc = any = 0;
- cutoff = ULLONG_MAX / base;
- cutlim = ULLONG_MAX % base;
- for ( ; ; c = *s++) {
- if (c >= '0' && c <= '9')
- c -= '0';
- else if (c >= 'A' && c <= 'Z')
- c -= 'A' - 10;
- else if (c >= 'a' && c <= 'z')
- c -= '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 = ULLONG_MAX;
- } else if (neg)
- acc = -acc;
- if (endptr != NULL)
- *endptr = (char *)(any ? s - 1 : nptr);
- return (acc);
- }
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