scc

 1#include <ctype.h>
 2#include <errno.h>
 3#include <limits.h>
 4#include <stdlib.h>
 5#include <string.h>
 6
 7#include "../libc.h"
 8
 9#undef strtoull
10
11unsigned long long
12strtoull(const char * restrict ptr, char ** restrict end, int base)
13{
14	int d, sign = 1;
15	unsigned long long n;
16	char *t, *s = (char *) ptr;
17
18	if (end)
19		*end = s;
20
21	while (isspace(*s))
22		++s;
23
24	switch (*s) {
25	case '-':
26		sign = -1;
27	case '+':
28		++s;
29	}
30
31	if (base == 0) {
32		if (*s == '0')
33			base = toupper(s[1]) == 'X' ? 16 : 8;
34		else
35			base = 10;
36	}
37	if (base == 16 && *s == '0' && toupper(s[1]) == 'X')
38		s += 2;
39
40	n = 0;
41	for (t = s; (d = _dtoi(*t)) < base; ++t) {
42		if (n > ULLONG_MAX/base)
43			goto overflow;
44		n *= base;
45		if (d > ULLONG_MAX - n)
46			goto overflow;
47		n += d;
48	}
49
50	if (end && t != s)
51		*end = t;
52
53	return n*sign;
54
55overflow:
56	if (end)
57		*end = t;
58	errno = ERANGE;
59
60	return ULLONG_MAX;
61}