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#include <string.h>
static const unsigned long long magic = 0x0101010101010101LL;
size_t strlen(const char *s)
{
const char *t = s;
unsigned long long word;
if (!s) return 0;
/* Byte compare up until 64 bit word boundary */
for (; ((unsigned long long) t & 7); t++)
if (!*t) return t - s;
/* Word compare */
do {
word = *((unsigned long long *) t); t += 8;
word = (word - magic) &~ word;
word &= (magic << 7);
} while (word == 0);
/* word & 0x8080808080808080 == word */
word = (word - 1) & (magic << 8);
word += (word << 32);
word += (word << 16);
word += (word << 8);
t += word >> 56;
return ((const char *) t) - 8 - s;
}
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