| /* |
| * memcpy.c |
| */ |
| |
| #include <string.h> |
| |
| void *memcpy(void *dst, const void *src, size_t n) |
| { |
| const char *p = src; |
| char *q = dst; |
| #if defined(__i386__) |
| asm volatile("cld ; movl %0,%%edx ; shrl $2,%0 ; rep ; movsl ; " |
| "movl %%edx,%0 ; andl $3,%0 ; rep ; movsb" |
| : "+c" (n), "+S" (p), "+D" (q) :: "edx"); |
| #elif defined(__x86_64__) |
| asm volatile("cld ; movq %0,%%rdx ; shrq $3,%0 ; rep ; movsq ; " |
| "movq %%rdx,%0 ; andl $7,%0 ; rep ; movsb" |
| : "+c" (n), "+S" (p), "+D" (q) :: "rdx"); |
| #else |
| while ( n-- ) { |
| *q++ = *p++; |
| } |
| #endif |
| |
| return dst; |
| } |