Gitiles
Code Review Sign In
gerrit-public.fairphone.software / kernel / msm-4.9 / bd1437e49d80fa3369ffbea9e73cde7f6d69e550 / . / arch / microblaze / lib / memmove.c
blob: d4e9f49a71f7b3a8ac57ab2178cf26cc6f63bff9 [file] [log] [blame]
Michal Simek322ae8e2009-03-27 14:25:21 +0100[diff] [blame]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 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, unsuccesfully, 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/types.h>
28#include <linux/stddef.h>
29#include <linux/compiler.h>
30#include <linux/module.h>
31#include <linux/string.h>
32
33#ifdef __HAVE_ARCH_MEMMOVE
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
39#ifdef CONFIG_OPT_LIB_FUNCTION
40 const uint32_t *i_src;
41 uint32_t *i_dst;
42#endif
43
44 if (!c)
45 return v_dst;
46
47 /* Use memcpy when source is higher than dest */
48 if (v_dst <= v_src)
49 return memcpy(v_dst, v_src, c);
50
51#ifndef CONFIG_OPT_LIB_FUNCTION
52 /* copy backwards, from end to beginning */
53 src += c;
54 dst += c;
55
56 /* Simple, byte oriented memmove. */
57 while (c--)
58 *--dst = *--src;
59
60 return v_dst;
61#else
62 /* The following code tries to optimize the copy by using unsigned
63 * alignment. This will work fine if both source and destination are
64 * aligned on the same boundary. However, if they are aligned on
65 * different boundaries shifts will be necessary. This might result in
66 * bad performance on MicroBlaze systems without a barrel shifter.
67 */
68 /* FIXME this part needs more test */
69 /* Do a descending copy - this is a bit trickier! */
70 dst += c;
71 src += c;
72
73 if (c >= 4) {
74 unsigned value, buf_hold;
75
76 /* Align the destination to a word boundry. */
77 /* This is done in an endian independant manner. */
78
79 switch ((unsigned long)dst & 3) {
80 case 3:
81 *--dst = *--src;
82 --c;
83 case 2:
84 *--dst = *--src;
85 --c;
86 case 1:
87 *--dst = *--src;
88 --c;
89 }
90
91 i_dst = (void *)dst;
92 /* Choose a copy scheme based on the source */
93 /* alignment relative to dstination. */
94 switch ((unsigned long)src & 3) {
95 case 0x0: /* Both byte offsets are aligned */
96
97 i_src = (const void *)src;
98
99 for (; c >= 4; c -= 4)
100 *--i_dst = *--i_src;
101
102 src = (const void *)i_src;
103 break;
104 case 0x1: /* Unaligned - Off by 1 */
105 /* Word align the source */
106 i_src = (const void *) (((unsigned)src + 4) & ~3);
107
108 /* Load the holding buffer */
109 buf_hold = *--i_src >> 24;
110
111 for (; c >= 4; c -= 4) {
112 value = *--i_src;
113 *--i_dst = buf_hold << 8 | value;
114 buf_hold = value >> 24;
115 }
116
117 /* Realign the source */
118 src = (const void *)i_src;
119 src += 1;
120 break;
121 case 0x2: /* Unaligned - Off by 2 */
122 /* Word align the source */
123 i_src = (const void *) (((unsigned)src + 4) & ~3);
124
125 /* Load the holding buffer */
126 buf_hold = *--i_src >> 16;
127
128 for (; c >= 4; c -= 4) {
129 value = *--i_src;
130 *--i_dst = buf_hold << 16 | value;
131 buf_hold = value >> 16;
132 }
133
134 /* Realign the source */
135 src = (const void *)i_src;
136 src += 2;
137 break;
138 case 0x3: /* Unaligned - Off by 3 */
139 /* Word align the source */
140 i_src = (const void *) (((unsigned)src + 4) & ~3);
141
142 /* Load the holding buffer */
143 buf_hold = *--i_src >> 8;
144
145 for (; c >= 4; c -= 4) {
146 value = *--i_src;
147 *--i_dst = buf_hold << 24 | value;
148 buf_hold = value >> 8;
149 }
150
151 /* Realign the source */
152 src = (const void *)i_src;
153 src += 3;
154 break;
155 }
156 dst = (void *)i_dst;
157 }
158
159 /* simple fast copy, ... unless a cache boundry is crossed */
160 /* Finish off any remaining bytes */
161 switch (c) {
162 case 4:
163 *--dst = *--src;
164 case 3:
165 *--dst = *--src;
166 case 2:
167 *--dst = *--src;
168 case 1:
169 *--dst = *--src;
170 }
171 return v_dst;
172#endif
173}
174EXPORT_SYMBOL(memmove);
175#endif /* __HAVE_ARCH_MEMMOVE */