21 lines
452 B
C
21 lines
452 B
C
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#include <string.h>
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#define BITOP(a,b,op) \
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((a)[(size_t)(b)/(8*sizeof *(a))] op (size_t)1<<((size_t)(b)%(8*sizeof *(a))))
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size_t strspn(const char *s, const char *c)
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{
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const char *a = s;
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size_t byteset[32/sizeof(size_t)] = { 0 };
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if (!c[0]) return 0;
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if (!c[1]) {
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for (; *s == *c; s++);
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return s-a;
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}
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for (; *c && BITOP(byteset, *(unsigned char *)c, |=); c++);
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for (; *s && BITOP(byteset, *(unsigned char *)s, &); s++);
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return s-a;
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}
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