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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 memmove.
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#include <linux/string.h>
32
33#ifdef CONFIG_OPT_LIB_FUNCTION
34void *memmove(void *v_dst, const void *v_src, __kernel_size_t c)
35{
36 const char *src = v_src;
37 char *dst = v_dst;
38 const uint32_t *i_src;
39 uint32_t *i_dst;
40
41 if (!c)
42 return v_dst;
43
44 /* Use memcpy when source is higher than dest */
45 if (v_dst <= v_src)
46 return memcpy(v_dst, v_src, c);
47
48 /* The following code tries to optimize the copy by using unsigned
49 * alignment. This will work fine if both source and destination are
50 * aligned on the same boundary. However, if they are aligned on
51 * different boundaries shifts will be necessary. This might result in
52 * bad performance on MicroBlaze systems without a barrel shifter.
53 */
54 /* FIXME this part needs more test */
55 /* Do a descending copy - this is a bit trickier! */
56 dst += c;
57 src += c;
58
59 if (c >= 4) {
60 unsigned value, buf_hold;
61
62 /* Align the destination to a word boundary. */
63 /* This is done in an endian independent manner. */
64
65 switch ((unsigned long)dst & 3) {
66 case 3:
67 *--dst = *--src;
68 --c;
69 fallthrough;
70 case 2:
71 *--dst = *--src;
72 --c;
73 fallthrough;
74 case 1:
75 *--dst = *--src;
76 --c;
77 }
78
79 i_dst = (void *)dst;
80 /* Choose a copy scheme based on the source */
81 /* alignment relative to destination. */
82 switch ((unsigned long)src & 3) {
83 case 0x0: /* Both byte offsets are aligned */
84
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 + 4) & ~3);
95#ifndef __MICROBLAZEEL__
96 /* Load the holding buffer */
97 buf_hold = *--i_src >> 24;
98
99 for (; c >= 4; c -= 4) {
100 value = *--i_src;
101 *--i_dst = buf_hold << 8 | value;
102 buf_hold = value >> 24;
103 }
104#else
105 /* Load the holding buffer */
106 buf_hold = (*--i_src & 0xFF) << 24;
107
108 for (; c >= 4; c -= 4) {
109 value = *--i_src;
110 *--i_dst = buf_hold |
111 ((value & 0xFFFFFF00) >> 8);
112 buf_hold = (value & 0xFF) << 24;
113 }
114#endif
115 /* Realign the source */
116 src = (const void *)i_src;
117 src += 1;
118 break;
119 case 0x2: /* Unaligned - Off by 2 */
120 /* Word align the source */
121 i_src = (const void *) (((unsigned)src + 4) & ~3);
122#ifndef __MICROBLAZEEL__
123 /* Load the holding buffer */
124 buf_hold = *--i_src >> 16;
125
126 for (; c >= 4; c -= 4) {
127 value = *--i_src;
128 *--i_dst = buf_hold << 16 | value;
129 buf_hold = value >> 16;
130 }
131#else
132 /* Load the holding buffer */
133 buf_hold = (*--i_src & 0xFFFF) << 16;
134
135 for (; c >= 4; c -= 4) {
136 value = *--i_src;
137 *--i_dst = buf_hold |
138 ((value & 0xFFFF0000) >> 16);
139 buf_hold = (value & 0xFFFF) << 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 + 4) & ~3);
149#ifndef __MICROBLAZEEL__
150 /* Load the holding buffer */
151 buf_hold = *--i_src >> 8;
152
153 for (; c >= 4; c -= 4) {
154 value = *--i_src;
155 *--i_dst = buf_hold << 24 | value;
156 buf_hold = value >> 8;
157 }
158#else
159 /* Load the holding buffer */
160 buf_hold = (*--i_src & 0xFFFFFF) << 8;
161
162 for (; c >= 4; c -= 4) {
163 value = *--i_src;
164 *--i_dst = buf_hold |
165 ((value & 0xFF000000) >> 24);
166 buf_hold = (value & 0xFFFFFF) << 8;
167 }
168#endif
169 /* Realign the source */
170 src = (const void *)i_src;
171 src += 3;
172 break;
173 }
174 dst = (void *)i_dst;
175 }
176
177 /* simple fast copy, ... unless a cache boundary is crossed */
178 /* Finish off any remaining bytes */
179 switch (c) {
180 case 4:
181 *--dst = *--src;
182 fallthrough;
183 case 3:
184 *--dst = *--src;
185 fallthrough;
186 case 2:
187 *--dst = *--src;
188 fallthrough;
189 case 1:
190 *--dst = *--src;
191 }
192 return v_dst;
193}
194EXPORT_SYMBOL(memmove);
195#endif /* CONFIG_OPT_LIB_FUNCTION */