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