1#include <string.h>
2
3#define BITOP(a,b,op) \
4 ((a)[(size_t)(b)/(8*sizeof *(a))] op (size_t)1<<((size_t)(b)%(8*sizeof *(a))))
5
6char *__strchrnul(const char *, int);
7
8size_t strcspn(const char *s, const char *c)
9{
10	const char *a = s;
11	size_t byteset[32/sizeof(size_t)];
12
13	if (!c[0] || !c[1]) return __strchrnul(s, *c)-a;
14
15	memset(byteset, 0, sizeof byteset);
16	for (; *c && BITOP(byteset, *(unsigned char *)c, |=); c++);
17	for (; *s && !BITOP(byteset, *(unsigned char *)s, &); s++);
18	return s-a;
19}
20