memdisk/memmove.c

/*
 * memmove.c
 */

#include <string.h>

void *memmove(void *dst, const void *src, size_t n)
{
	const char *p = src;
	char *q = dst;
#if defined(__i386__) || defined(__x86_64__)
	if (q < p) {
		asm volatile("cld; rep; movsb"
			     : "+c" (n), "+S"(p), "+D"(q));
	} else {
		p += (n - 1);
		q += (n - 1);
		asm volatile("std; rep; movsb; cld"
			     : "+c" (n), "+S"(p), "+D"(q));
	}
#else
	if (q < p) {
		while (n--) {
			*q++ = *p++;
		}
	} else {
		p += n;
		q += n;
		while (n--) {
			*--q = *--p;
		}
	}
#endif

	return dst;
}