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 *
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 __HAVE_ARCH_MEMCPY
35 #ifndef CONFIG_OPT_LIB_FUNCTION
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
41 /* Simple, byte oriented memcpy. */
42 while (c--)
43 *dst++ = *src++;
44
45 return v_dst;
46 }
47 #else /* CONFIG_OPT_LIB_FUNCTION */
48 void *memcpy(void *v_dst, const void *v_src, __kernel_size_t c)
49 {
50 const char *src = v_src;
51 char *dst = v_dst;
52
53 /* The following code tries to optimize the copy by using unsigned
54 * alignment. This will work fine if both source and destination are
55 * aligned on the same boundary. However, if they are aligned on
56 * different boundaries shifts will be necessary. This might result in
57 * bad performance on MicroBlaze systems without a barrel shifter.
58 */
59 const uint32_t *i_src;
60 uint32_t *i_dst;
61
62 if (likely(c >= 4)) {
63 unsigned value, buf_hold;
64
65 /* Align the destination to a word boundary. */
66 /* This is done in an endian independent manner. */
67 switch ((unsigned long)dst & 3) {
68 case 1:
69 *dst++ = *src++;
70 --c;
71 case 2:
72 *dst++ = *src++;
73 --c;
74 case 3:
75 *dst++ = *src++;
76 --c;
77 }
78
79 i_dst = (void *)dst;
80
81 /* Choose a copy scheme based on the source */
82 /* alignment relative to destination. */
83 switch ((unsigned long)src & 3) {
84 case 0x0: /* Both byte offsets are aligned */
85 i_src = (const void *)src;
86
87 for (; c >= 4; c -= 4)
88 *i_dst++ = *i_src++;
89
90 src = (const void *)i_src;
91 break;
92 case 0x1: /* Unaligned - Off by 1 */
93 /* Word align the source */
94 i_src = (const void *) ((unsigned)src & ~3);
95 #ifndef __MICROBLAZEEL__
96 /* Load the holding buffer */
97 buf_hold = *i_src++ << 8;
98
99 for (; c >= 4; c -= 4) {
100 value = *i_src++;
101 *i_dst++ = buf_hold | value >> 24;
102 buf_hold = value << 8;
103 }
104 #else
105 /* Load the holding buffer */
106 buf_hold = (*i_src++ & 0xFFFFFF00) >> 8;
107
108 for (; c >= 4; c -= 4) {
109 value = *i_src++;
110 *i_dst++ = buf_hold | ((value & 0xFF) << 24);
111 buf_hold = (value & 0xFFFFFF00) >> 8;
112 }
113 #endif
114 /* Realign the source */
115 src = (const void *)i_src;
116 src -= 3;
117 break;
118 case 0x2: /* Unaligned - Off by 2 */
119 /* Word align the source */
120 i_src = (const void *) ((unsigned)src & ~3);
121 #ifndef __MICROBLAZEEL__
122 /* Load the holding buffer */
123 buf_hold = *i_src++ << 16;
124
125 for (; c >= 4; c -= 4) {
126 value = *i_src++;
127 *i_dst++ = buf_hold | value >> 16;
128 buf_hold = value << 16;
129 }
130 #else
131 /* Load the holding buffer */
132 buf_hold = (*i_src++ & 0xFFFF0000) >> 16;
133
134 for (; c >= 4; c -= 4) {
135 value = *i_src++;
136 *i_dst++ = buf_hold | ((value & 0xFFFF) << 16);
137 buf_hold = (value & 0xFFFF0000) >> 16;
138 }
139 #endif
140 /* Realign the source */
141 src = (const void *)i_src;
142 src -= 2;
143 break;
144 case 0x3: /* Unaligned - Off by 3 */
145 /* Word align the source */
146 i_src = (const void *) ((unsigned)src & ~3);
147 #ifndef __MICROBLAZEEL__
148 /* Load the holding buffer */
149 buf_hold = *i_src++ << 24;
150
151 for (; c >= 4; c -= 4) {
152 value = *i_src++;
153 *i_dst++ = buf_hold | value >> 8;
154 buf_hold = value << 24;
155 }
156 #else
157 /* Load the holding buffer */
158 buf_hold = (*i_src++ & 0xFF000000) >> 24;
159
160 for (; c >= 4; c -= 4) {
161 value = *i_src++;
162 *i_dst++ = buf_hold | ((value & 0xFFFFFF) << 8);
163 buf_hold = (value & 0xFF000000) >> 24;
164 }
165 #endif
166 /* Realign the source */
167 src = (const void *)i_src;
168 src -= 1;
169 break;
170 }
171 dst = (void *)i_dst;
172 }
173
174 /* Finish off any remaining bytes */
175 /* simple fast copy, ... unless a cache boundary is crossed */
176 switch (c) {
177 case 3:
178 *dst++ = *src++;
179 case 2:
180 *dst++ = *src++;
181 case 1:
182 *dst++ = *src++;
183 }
184
185 return v_dst;
186 }
187 #endif /* CONFIG_OPT_LIB_FUNCTION */
188 EXPORT_SYMBOL(memcpy);
189 #endif /* __HAVE_ARCH_MEMCPY */