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