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1 | /* |
2 | * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu> | |
3 | * Copyright (C) 2008-2009 PetaLogix | |
4 | * Copyright (C) 2007 John Williams | |
5 | * | |
6 | * Reasonably optimised generic C-code for memcpy on Microblaze | |
7 | * This is generic C code to do efficient, alignment-aware memcpy. | |
8 | * | |
9 | * It is based on demo code originally Copyright 2001 by Intel Corp, taken from | |
10 | * http://www.embedded.com/showArticle.jhtml?articleID=19205567 | |
11 | * | |
af901ca1 | 12 | * Attempts were made, unsuccessfully, to contact the original |
322ae8eb MS |
13 | * author of this code (Michael Morrow, Intel). Below is the original |
14 | * copyright notice. | |
15 | * | |
16 | * This software has been developed by Intel Corporation. | |
17 | * Intel specifically disclaims all warranties, express or | |
18 | * implied, and all liability, including consequential and | |
19 | * other indirect damages, for the use of this program, including | |
20 | * liability for infringement of any proprietary rights, | |
21 | * and including the warranties of merchantability and fitness | |
22 | * for a particular purpose. Intel does not assume any | |
23 | * responsibility for and errors which may appear in this program | |
24 | * not any responsibility to update it. | |
25 | */ | |
26 | ||
27 | #include <linux/types.h> | |
28 | #include <linux/stddef.h> | |
29 | #include <linux/compiler.h> | |
30 | #include <linux/module.h> | |
31 | ||
32 | #include <linux/string.h> | |
33 | #include <asm/system.h> | |
34 | ||
35 | #ifdef __HAVE_ARCH_MEMCPY | |
36 | void *memcpy(void *v_dst, const void *v_src, __kernel_size_t c) | |
37 | { | |
38 | const char *src = v_src; | |
39 | char *dst = v_dst; | |
40 | #ifndef CONFIG_OPT_LIB_FUNCTION | |
41 | /* Simple, byte oriented memcpy. */ | |
42 | while (c--) | |
43 | *dst++ = *src++; | |
44 | ||
45 | return v_dst; | |
46 | #else | |
47 | /* The following code tries to optimize the copy by using unsigned | |
48 | * alignment. This will work fine if both source and destination are | |
49 | * aligned on the same boundary. However, if they are aligned on | |
50 | * different boundaries shifts will be necessary. This might result in | |
51 | * bad performance on MicroBlaze systems without a barrel shifter. | |
52 | */ | |
53 | const uint32_t *i_src; | |
54 | uint32_t *i_dst; | |
55 | ||
56 | if (c >= 4) { | |
57 | unsigned value, buf_hold; | |
58 | ||
59 | /* Align the dstination to a word boundry. */ | |
60 | /* This is done in an endian independant manner. */ | |
61 | switch ((unsigned long)dst & 3) { | |
62 | case 1: | |
63 | *dst++ = *src++; | |
64 | --c; | |
65 | case 2: | |
66 | *dst++ = *src++; | |
67 | --c; | |
68 | case 3: | |
69 | *dst++ = *src++; | |
70 | --c; | |
71 | } | |
72 | ||
73 | i_dst = (void *)dst; | |
74 | ||
75 | /* Choose a copy scheme based on the source */ | |
76 | /* alignment relative to dstination. */ | |
77 | switch ((unsigned long)src & 3) { | |
78 | case 0x0: /* Both byte offsets are aligned */ | |
79 | i_src = (const void *)src; | |
80 | ||
81 | for (; c >= 4; c -= 4) | |
82 | *i_dst++ = *i_src++; | |
83 | ||
84 | src = (const void *)i_src; | |
85 | break; | |
86 | case 0x1: /* Unaligned - Off by 1 */ | |
87 | /* Word align the source */ | |
88 | i_src = (const void *) ((unsigned)src & ~3); | |
89 | ||
90 | /* Load the holding buffer */ | |
91 | buf_hold = *i_src++ << 8; | |
92 | ||
93 | for (; c >= 4; c -= 4) { | |
94 | value = *i_src++; | |
95 | *i_dst++ = buf_hold | value >> 24; | |
96 | buf_hold = value << 8; | |
97 | } | |
98 | ||
99 | /* Realign the source */ | |
100 | src = (const void *)i_src; | |
101 | src -= 3; | |
102 | break; | |
103 | case 0x2: /* Unaligned - Off by 2 */ | |
104 | /* Word align the source */ | |
105 | i_src = (const void *) ((unsigned)src & ~3); | |
106 | ||
107 | /* Load the holding buffer */ | |
108 | buf_hold = *i_src++ << 16; | |
109 | ||
110 | for (; c >= 4; c -= 4) { | |
111 | value = *i_src++; | |
112 | *i_dst++ = buf_hold | value >> 16; | |
113 | buf_hold = value << 16; | |
114 | } | |
115 | ||
116 | /* Realign the source */ | |
117 | src = (const void *)i_src; | |
118 | src -= 2; | |
119 | break; | |
120 | case 0x3: /* Unaligned - Off by 3 */ | |
121 | /* Word align the source */ | |
122 | i_src = (const void *) ((unsigned)src & ~3); | |
123 | ||
124 | /* Load the holding buffer */ | |
125 | buf_hold = *i_src++ << 24; | |
126 | ||
127 | for (; c >= 4; c -= 4) { | |
128 | value = *i_src++; | |
129 | *i_dst++ = buf_hold | value >> 8; | |
130 | buf_hold = value << 24; | |
131 | } | |
132 | ||
133 | /* Realign the source */ | |
134 | src = (const void *)i_src; | |
135 | src -= 1; | |
136 | break; | |
137 | } | |
138 | dst = (void *)i_dst; | |
139 | } | |
140 | ||
141 | /* Finish off any remaining bytes */ | |
142 | /* simple fast copy, ... unless a cache boundry is crossed */ | |
143 | switch (c) { | |
144 | case 3: | |
145 | *dst++ = *src++; | |
146 | case 2: | |
147 | *dst++ = *src++; | |
148 | case 1: | |
149 | *dst++ = *src++; | |
150 | } | |
151 | ||
152 | return v_dst; | |
153 | #endif | |
154 | } | |
155 | EXPORT_SYMBOL(memcpy); | |
156 | #endif /* __HAVE_ARCH_MEMCPY */ |