ref: ec4c79f3a6ed97ec0c407a870827382cbefb1166
dir: /src/libc/string/memmove.c/
#include <string.h>
#undef memmove
void *
memmove(void *s1, const void *s2, size_t n)
{
	char *d = s1;
	const char *s = s2;
	if (d < s) {
		while (n-- > 0)
			*d++ = *s++;
	} else {
		s += n-1, d += n-1;
		while (n-- > 0)
			*d-- = *s--;
	}
	return s1;
}