23 lines
514 B
C
23 lines
514 B
C
#include <string.h>
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#include <stdint.h>
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#include <limits.h>
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#define ALIGN (sizeof(size_t))
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#define ONES ((size_t)-1/UCHAR_MAX)
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#define HIGHS (ONES * (UCHAR_MAX/2+1))
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#define HASZERO(x) ((x)-ONES & ~(x) & HIGHS)
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size_t strlen(const char *s)
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{
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const char *a = s;
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#ifdef __GNUC__
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typedef size_t __attribute__((__may_alias__)) word;
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const word *w;
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for (; (uintptr_t)s % ALIGN; s++) if (!*s) return s-a;
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for (w = (const void *)s; !HASZERO(*w); w++);
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s = (const void *)w;
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#endif
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for (; *s; s++);
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return s-a;
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}
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