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867e359b CM |
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 | ||
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; | |
0707ad30 | 45 | } |
867e359b CM |
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); |