1 /*
2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
12 * more details.
13 */
14
15 #include <linux/types.h>
16 #include <linux/string.h>
17 #include <linux/module.h>
18
memmove(void * dest,const void * src,size_t n)19 void *memmove(void *dest, const void *src, size_t n)
20 {
21 if ((const char *)src >= (char *)dest + n
22 || (char *)dest >= (const char *)src + n) {
23 /* We found no overlap, so let memcpy do all the heavy
24 * lifting (prefetching, etc.)
25 */
26 return memcpy(dest, src, n);
27 }
28
29 if (n != 0) {
30 const uint8_t *in;
31 uint8_t x;
32 uint8_t *out;
33 int stride;
34
35 if (src < dest) {
36 /* copy backwards */
37 in = (const uint8_t *)src + n - 1;
38 out = (uint8_t *)dest + n - 1;
39 stride = -1;
40 } else {
41 /* copy forwards */
42 in = (const uint8_t *)src;
43 out = (uint8_t *)dest;
44 stride = 1;
45 }
46
47 /* Manually software-pipeline this loop. */
48 x = *in;
49 in += stride;
50
51 while (--n != 0) {
52 *out = x;
53 out += stride;
54 x = *in;
55 in += stride;
56 }
57
58 *out = x;
59 }
60
61 return dest;
62 }
63 EXPORT_SYMBOL(memmove);
64