usr/klibc/memcpy.c

/*
 * memcpy.c
 */

#include <string.h>
#include <stdint.h>

void *memcpy(void *dst, const void *src, size_t n)
{
	const char *p = src;
	char *q = dst;
#if defined(__i386__)
	size_t nl = n >> 2;
	asm volatile ("cld ; rep ; movsl ; movl %3,%0 ; rep ; movsb":"+c" (nl),
		      "+S"(p), "+D"(q)
		      :"r"(n & 3));
#elif defined(__x86_64__)
	size_t nq = n >> 3;
	asm volatile ("cld ; rep ; movsq ; movl %3,%%ecx ; rep ; movsb":"+c"
		      (nq), "+S"(p), "+D"(q)
		      :"r"((uint32_t) (n & 7)));
#else
	while (n--) {
		*q++ = *p++;
	}
#endif

	return dst;
}