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
memcpy(void * v_dst,const void * v_src,__kernel_size_t c)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 */
memcpy(void * v_dst,const void * v_src,__kernel_size_t c)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 fallthrough;
72 case 2:
73 *dst++ = *src++;
74 --c;
75 fallthrough;
76 case 3:
77 *dst++ = *src++;
78 --c;
79 }
80
81 i_dst = (void *)dst;
82
83 /* Choose a copy scheme based on the source */
84 /* alignment relative to destination. */
85 switch ((unsigned long)src & 3) {
86 case 0x0: /* Both byte offsets are aligned */
87 i_src = (const void *)src;
88
89 for (; c >= 4; c -= 4)
90 *i_dst++ = *i_src++;
91
92 src = (const void *)i_src;
93 break;
94 case 0x1: /* Unaligned - Off by 1 */
95 /* Word align the source */
96 i_src = (const void *) ((unsigned)src & ~3);
97 #ifndef __MICROBLAZEEL__
98 /* Load the holding buffer */
99 buf_hold = *i_src++ << 8;
100
101 for (; c >= 4; c -= 4) {
102 value = *i_src++;
103 *i_dst++ = buf_hold | value >> 24;
104 buf_hold = value << 8;
105 }
106 #else
107 /* Load the holding buffer */
108 buf_hold = (*i_src++ & 0xFFFFFF00) >> 8;
109
110 for (; c >= 4; c -= 4) {
111 value = *i_src++;
112 *i_dst++ = buf_hold | ((value & 0xFF) << 24);
113 buf_hold = (value & 0xFFFFFF00) >> 8;
114 }
115 #endif
116 /* Realign the source */
117 src = (const void *)i_src;
118 src -= 3;
119 break;
120 case 0x2: /* Unaligned - Off by 2 */
121 /* Word align the source */
122 i_src = (const void *) ((unsigned)src & ~3);
123 #ifndef __MICROBLAZEEL__
124 /* Load the holding buffer */
125 buf_hold = *i_src++ << 16;
126
127 for (; c >= 4; c -= 4) {
128 value = *i_src++;
129 *i_dst++ = buf_hold | value >> 16;
130 buf_hold = value << 16;
131 }
132 #else
133 /* Load the holding buffer */
134 buf_hold = (*i_src++ & 0xFFFF0000) >> 16;
135
136 for (; c >= 4; c -= 4) {
137 value = *i_src++;
138 *i_dst++ = buf_hold | ((value & 0xFFFF) << 16);
139 buf_hold = (value & 0xFFFF0000) >> 16;
140 }
141 #endif
142 /* Realign the source */
143 src = (const void *)i_src;
144 src -= 2;
145 break;
146 case 0x3: /* Unaligned - Off by 3 */
147 /* Word align the source */
148 i_src = (const void *) ((unsigned)src & ~3);
149 #ifndef __MICROBLAZEEL__
150 /* Load the holding buffer */
151 buf_hold = *i_src++ << 24;
152
153 for (; c >= 4; c -= 4) {
154 value = *i_src++;
155 *i_dst++ = buf_hold | value >> 8;
156 buf_hold = value << 24;
157 }
158 #else
159 /* Load the holding buffer */
160 buf_hold = (*i_src++ & 0xFF000000) >> 24;
161
162 for (; c >= 4; c -= 4) {
163 value = *i_src++;
164 *i_dst++ = buf_hold | ((value & 0xFFFFFF) << 8);
165 buf_hold = (value & 0xFF000000) >> 24;
166 }
167 #endif
168 /* Realign the source */
169 src = (const void *)i_src;
170 src -= 1;
171 break;
172 }
173 dst = (void *)i_dst;
174 }
175
176 /* Finish off any remaining bytes */
177 /* simple fast copy, ... unless a cache boundary is crossed */
178 switch (c) {
179 case 3:
180 *dst++ = *src++;
181 fallthrough;
182 case 2:
183 *dst++ = *src++;
184 fallthrough;
185 case 1:
186 *dst++ = *src++;
187 }
188
189 return v_dst;
190 }
191 #endif /* CONFIG_OPT_LIB_FUNCTION */
192 EXPORT_SYMBOL(memcpy);
193 #endif /* __HAVE_ARCH_MEMCPY */
194