1#include <string.h>
2#include <stdint.h>
3
4#define WT size_t
5#define WS (sizeof(WT))
6
7void *memmove(void *dest, const void *src, size_t n)
8{
9	char *d = dest;
10	const char *s = src;
11
12	if (d==s) return d;
13	if (s+n <= d || d+n <= s) return memcpy(d, s, n);
14
15	if (d<s) {
16		if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
17			while ((uintptr_t)d % WS) {
18				if (!n--) return dest;
19				*d++ = *s++;
20			}
21			for (; n>=WS; n-=WS, d+=WS, s+=WS) *(WT *)d = *(WT *)s;
22		}
23		for (; n; n--) *d++ = *s++;
24	} else {
25		if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
26			while ((uintptr_t)(d+n) % WS) {
27				if (!n--) return dest;
28				d[n] = s[n];
29			}
30			while (n>=WS) n-=WS, *(WT *)(d+n) = *(WT *)(s+n);
31		}
32		while (n) n--, d[n] = s[n];
33	}
34
35	return dest;
36}
37