xref: /aosp_15_r20/external/musl/src/string/strspn.c (revision c9945492fdd68bbe62686c5b452b4dc1be3f8453)
1*c9945492SAndroid Build Coastguard Worker #include <string.h>
2*c9945492SAndroid Build Coastguard Worker 
3*c9945492SAndroid Build Coastguard Worker #define BITOP(a,b,op) \
4*c9945492SAndroid Build Coastguard Worker  ((a)[(size_t)(b)/(8*sizeof *(a))] op (size_t)1<<((size_t)(b)%(8*sizeof *(a))))
5*c9945492SAndroid Build Coastguard Worker 
strspn(const char * s,const char * c)6*c9945492SAndroid Build Coastguard Worker size_t strspn(const char *s, const char *c)
7*c9945492SAndroid Build Coastguard Worker {
8*c9945492SAndroid Build Coastguard Worker 	const char *a = s;
9*c9945492SAndroid Build Coastguard Worker 	size_t byteset[32/sizeof(size_t)] = { 0 };
10*c9945492SAndroid Build Coastguard Worker 
11*c9945492SAndroid Build Coastguard Worker 	if (!c[0]) return 0;
12*c9945492SAndroid Build Coastguard Worker 	if (!c[1]) {
13*c9945492SAndroid Build Coastguard Worker 		for (; *s == *c; s++);
14*c9945492SAndroid Build Coastguard Worker 		return s-a;
15*c9945492SAndroid Build Coastguard Worker 	}
16*c9945492SAndroid Build Coastguard Worker 
17*c9945492SAndroid Build Coastguard Worker 	for (; *c && BITOP(byteset, *(unsigned char *)c, |=); c++);
18*c9945492SAndroid Build Coastguard Worker 	for (; *s && BITOP(byteset, *(unsigned char *)s, &); s++);
19*c9945492SAndroid Build Coastguard Worker 	return s-a;
20*c9945492SAndroid Build Coastguard Worker }
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