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[pohmelfs.git] / arch / microblaze / lib / memcpy.c
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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
6 * Reasonably optimised generic C-code for memcpy on Microblaze
7 * This is generic C code to do efficient, alignment-aware memcpy.
9 * It is based on demo code originally Copyright 2001 by Intel Corp, taken from
10 * http://www.embedded.com/showArticle.jhtml?articleID=19205567
12 * Attempts were made, unsuccessfully, to contact the original
13 * author of this code (Michael Morrow, Intel). Below is the original
14 * copyright notice.
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.
27 #include <linux/types.h>
28 #include <linux/stddef.h>
29 #include <linux/compiler.h>
30 #include <linux/module.h>
32 #include <linux/string.h>
33 #include <asm/system.h>
35 #ifdef __HAVE_ARCH_MEMCPY
36 #ifndef CONFIG_OPT_LIB_FUNCTION
37 void *memcpy(void *v_dst, const void *v_src, __kernel_size_t c)
39 const char *src = v_src;
40 char *dst = v_dst;
42 /* Simple, byte oriented memcpy. */
43 while (c--)
44 *dst++ = *src++;
46 return v_dst;
48 #else /* CONFIG_OPT_LIB_FUNCTION */
49 void *memcpy(void *v_dst, const void *v_src, __kernel_size_t c)
51 const char *src = v_src;
52 char *dst = v_dst;
54 /* The following code tries to optimize the copy by using unsigned
55 * alignment. This will work fine if both source and destination are
56 * aligned on the same boundary. However, if they are aligned on
57 * different boundaries shifts will be necessary. This might result in
58 * bad performance on MicroBlaze systems without a barrel shifter.
60 const uint32_t *i_src;
61 uint32_t *i_dst;
63 if (likely(c >= 4)) {
64 unsigned value, buf_hold;
66 /* Align the destination to a word boundary. */
67 /* This is done in an endian independent manner. */
68 switch ((unsigned long)dst & 3) {
69 case 1:
70 *dst++ = *src++;
71 --c;
72 case 2:
73 *dst++ = *src++;
74 --c;
75 case 3:
76 *dst++ = *src++;
77 --c;
80 i_dst = (void *)dst;
82 /* Choose a copy scheme based on the source */
83 /* alignment relative to destination. */
84 switch ((unsigned long)src & 3) {
85 case 0x0: /* Both byte offsets are aligned */
86 i_src = (const void *)src;
88 for (; c >= 4; c -= 4)
89 *i_dst++ = *i_src++;
91 src = (const void *)i_src;
92 break;
93 case 0x1: /* Unaligned - Off by 1 */
94 /* Word align the source */
95 i_src = (const void *) ((unsigned)src & ~3);
96 #ifndef __MICROBLAZEEL__
97 /* Load the holding buffer */
98 buf_hold = *i_src++ << 8;
100 for (; c >= 4; c -= 4) {
101 value = *i_src++;
102 *i_dst++ = buf_hold | value >> 24;
103 buf_hold = value << 8;
105 #else
106 /* Load the holding buffer */
107 buf_hold = (*i_src++ & 0xFFFFFF00) >>8;
109 for (; c >= 4; c -= 4) {
110 value = *i_src++;
111 *i_dst++ = buf_hold | ((value & 0xFF) << 24);
112 buf_hold = (value & 0xFFFFFF00) >>8;
114 #endif
115 /* Realign the source */
116 src = (const void *)i_src;
117 src -= 3;
118 break;
119 case 0x2: /* Unaligned - Off by 2 */
120 /* Word align the source */
121 i_src = (const void *) ((unsigned)src & ~3);
122 #ifndef __MICROBLAZEEL__
123 /* Load the holding buffer */
124 buf_hold = *i_src++ << 16;
126 for (; c >= 4; c -= 4) {
127 value = *i_src++;
128 *i_dst++ = buf_hold | value >> 16;
129 buf_hold = value << 16;
131 #else
132 /* Load the holding buffer */
133 buf_hold = (*i_src++ & 0xFFFF0000 )>>16;
135 for (; c >= 4; c -= 4) {
136 value = *i_src++;
137 *i_dst++ = buf_hold | ((value & 0xFFFF)<<16);
138 buf_hold = (value & 0xFFFF0000) >>16;
140 #endif
141 /* Realign the source */
142 src = (const void *)i_src;
143 src -= 2;
144 break;
145 case 0x3: /* Unaligned - Off by 3 */
146 /* Word align the source */
147 i_src = (const void *) ((unsigned)src & ~3);
148 #ifndef __MICROBLAZEEL__
149 /* Load the holding buffer */
150 buf_hold = *i_src++ << 24;
152 for (; c >= 4; c -= 4) {
153 value = *i_src++;
154 *i_dst++ = buf_hold | value >> 8;
155 buf_hold = value << 24;
157 #else
158 /* Load the holding buffer */
159 buf_hold = (*i_src++ & 0xFF000000) >> 24;
161 for (; c >= 4; c -= 4) {
162 value = *i_src++;
163 *i_dst++ = buf_hold | ((value & 0xFFFFFF) << 8);
164 buf_hold = (value & 0xFF000000) >> 24;
166 #endif
167 /* Realign the source */
168 src = (const void *)i_src;
169 src -= 1;
170 break;
172 dst = (void *)i_dst;
175 /* Finish off any remaining bytes */
176 /* simple fast copy, ... unless a cache boundary is crossed */
177 switch (c) {
178 case 3:
179 *dst++ = *src++;
180 case 2:
181 *dst++ = *src++;
182 case 1:
183 *dst++ = *src++;
186 return v_dst;
188 #endif /* CONFIG_OPT_LIB_FUNCTION */
189 EXPORT_SYMBOL(memcpy);
190 #endif /* __HAVE_ARCH_MEMCPY */