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179 lines · 4.6 KiB

1/*
2 * Copyright (C) 2008-2009 Michal Simek <[email protected]>
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 *
12 * Attempts were made, unsuccessfully, to contact the original
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/export.h>
28#include <linux/types.h>
29#include <linux/stddef.h>
30#include <linux/compiler.h>
31
32#include <linux/string.h>
33
34#ifdef CONFIG_OPT_LIB_FUNCTION
35void *memcpy(void *v_dst, const void *v_src, __kernel_size_t c)
36{
37 const char *src = v_src;
38 char *dst = v_dst;
39
40 /* The following code tries to optimize the copy by using unsigned
41 * alignment. This will work fine if both source and destination are
42 * aligned on the same boundary. However, if they are aligned on
43 * different boundaries shifts will be necessary. This might result in
44 * bad performance on MicroBlaze systems without a barrel shifter.
45 */
46 const uint32_t *i_src;
47 uint32_t *i_dst;
48
49 if (likely(c >= 4)) {
50 unsigned value, buf_hold;
51
52 /* Align the destination to a word boundary. */
53 /* This is done in an endian independent manner. */
54 switch ((unsigned long)dst & 3) {
55 case 1:
56 *dst++ = *src++;
57 --c;
58 fallthrough;
59 case 2:
60 *dst++ = *src++;
61 --c;
62 fallthrough;
63 case 3:
64 *dst++ = *src++;
65 --c;
66 }
67
68 i_dst = (void *)dst;
69
70 /* Choose a copy scheme based on the source */
71 /* alignment relative to destination. */
72 switch ((unsigned long)src & 3) {
73 case 0x0: /* Both byte offsets are aligned */
74 i_src = (const void *)src;
75
76 for (; c >= 4; c -= 4)
77 *i_dst++ = *i_src++;
78
79 src = (const void *)i_src;
80 break;
81 case 0x1: /* Unaligned - Off by 1 */
82 /* Word align the source */
83 i_src = (const void *) ((unsigned)src & ~3);
84#ifndef __MICROBLAZEEL__
85 /* Load the holding buffer */
86 buf_hold = *i_src++ << 8;
87
88 for (; c >= 4; c -= 4) {
89 value = *i_src++;
90 *i_dst++ = buf_hold | value >> 24;
91 buf_hold = value << 8;
92 }
93#else
94 /* Load the holding buffer */
95 buf_hold = (*i_src++ & 0xFFFFFF00) >> 8;
96
97 for (; c >= 4; c -= 4) {
98 value = *i_src++;
99 *i_dst++ = buf_hold | ((value & 0xFF) << 24);
100 buf_hold = (value & 0xFFFFFF00) >> 8;
101 }
102#endif
103 /* Realign the source */
104 src = (const void *)i_src;
105 src -= 3;
106 break;
107 case 0x2: /* Unaligned - Off by 2 */
108 /* Word align the source */
109 i_src = (const void *) ((unsigned)src & ~3);
110#ifndef __MICROBLAZEEL__
111 /* Load the holding buffer */
112 buf_hold = *i_src++ << 16;
113
114 for (; c >= 4; c -= 4) {
115 value = *i_src++;
116 *i_dst++ = buf_hold | value >> 16;
117 buf_hold = value << 16;
118 }
119#else
120 /* Load the holding buffer */
121 buf_hold = (*i_src++ & 0xFFFF0000) >> 16;
122
123 for (; c >= 4; c -= 4) {
124 value = *i_src++;
125 *i_dst++ = buf_hold | ((value & 0xFFFF) << 16);
126 buf_hold = (value & 0xFFFF0000) >> 16;
127 }
128#endif
129 /* Realign the source */
130 src = (const void *)i_src;
131 src -= 2;
132 break;
133 case 0x3: /* Unaligned - Off by 3 */
134 /* Word align the source */
135 i_src = (const void *) ((unsigned)src & ~3);
136#ifndef __MICROBLAZEEL__
137 /* Load the holding buffer */
138 buf_hold = *i_src++ << 24;
139
140 for (; c >= 4; c -= 4) {
141 value = *i_src++;
142 *i_dst++ = buf_hold | value >> 8;
143 buf_hold = value << 24;
144 }
145#else
146 /* Load the holding buffer */
147 buf_hold = (*i_src++ & 0xFF000000) >> 24;
148
149 for (; c >= 4; c -= 4) {
150 value = *i_src++;
151 *i_dst++ = buf_hold | ((value & 0xFFFFFF) << 8);
152 buf_hold = (value & 0xFF000000) >> 24;
153 }
154#endif
155 /* Realign the source */
156 src = (const void *)i_src;
157 src -= 1;
158 break;
159 }
160 dst = (void *)i_dst;
161 }
162
163 /* Finish off any remaining bytes */
164 /* simple fast copy, ... unless a cache boundary is crossed */
165 switch (c) {
166 case 3:
167 *dst++ = *src++;
168 fallthrough;
169 case 2:
170 *dst++ = *src++;
171 fallthrough;
172 case 1:
173 *dst++ = *src++;
174 }
175
176 return v_dst;
177}
178EXPORT_SYMBOL(memcpy);
179#endif /* CONFIG_OPT_LIB_FUNCTION */