1 #include <string.h>
2 #include <stdint.h>
3
4 #ifdef __GNUC__
5 typedef __attribute__((__may_alias__)) size_t WT;
6 #define WS (sizeof(WT))
7 #endif
8
memmove(void * dest,const void * src,size_t n)9 void *memmove(void *dest, const void *src, size_t n)
10 {
11 char *d = dest;
12 const char *s = src;
13
14 if (d==s) return d;
15 if ((uintptr_t)s-(uintptr_t)d-n <= -2*n) return memcpy(d, s, n);
16
17 if (d<s) {
18 #ifdef __GNUC__
19 if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
20 while ((uintptr_t)d % WS) {
21 if (!n--) return dest;
22 *d++ = *s++;
23 }
24 for (; n>=WS; n-=WS, d+=WS, s+=WS) *(WT *)d = *(WT *)s;
25 }
26 #endif
27 for (; n; n--) *d++ = *s++;
28 } else {
29 #ifdef __GNUC__
30 if ((uintptr_t)s % WS == (uintptr_t)d % WS) {
31 while ((uintptr_t)(d+n) % WS) {
32 if (!n--) return dest;
33 d[n] = s[n];
34 }
35 while (n>=WS) n-=WS, *(WT *)(d+n) = *(WT *)(s+n);
36 }
37 #endif
38 while (n) n--, d[n] = s[n];
39 }
40
41 return dest;
42 }
43