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Michal Simek322ae8e2009-03-27 14:25:21 +01001/*
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 *
André Goddard Rosaaf901ca2009-11-14 13:09:05 -020012 * Attempts were made, unsuccessfully, to contact the original
Michal Simek322ae8e2009-03-27 14:25:21 +010013 * 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
36void *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}
155EXPORT_SYMBOL(memcpy);
156#endif /* __HAVE_ARCH_MEMCPY */