1 /* 2 * memset.c 3 */ 4 5 #include <string.h> 6 #include <stdint.h> 7 8 void *memset(void *dst, int c, size_t n) 9 { 10 char *q = dst; 11 12 #if defined(__i386__) 13 size_t nl = n >> 2; 14 asm volatile ("cld ; rep ; stosl ; movl %3,%0 ; rep ; stosb" 15 : "+c" (nl), "+D" (q) 16 : "a" ((unsigned char)c * 0x01010101U), "r" (n & 3)); 17 #elif defined(__x86_64__) 18 size_t nq = n >> 3; 19 asm volatile ("cld ; rep ; stosq ; movl %3,%%ecx ; rep ; stosb" 20 :"+c" (nq), "+D" (q) 21 : "a" ((unsigned char)c * 0x0101010101010101U), 22 "r" ((uint32_t) n & 7)); 23 #else 24 while (n--) { 25 *q++ = c; 26 } 27 #endif 28 29 return dst; 30 } 31
