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 memmove.
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
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>
31 #include <linux/string.h>
33 #ifdef __HAVE_ARCH_MEMMOVE
34 #ifndef CONFIG_OPT_LIB_FUNCTION
35 void *memmove(void *v_dst, const void *v_src, __kernel_size_t c)
37 const char *src = v_src;
43 /* Use memcpy when source is higher than dest */
45 return memcpy(v_dst, v_src, c);
47 /* copy backwards, from end to beginning */
51 /* Simple, byte oriented memmove. */
57 #else /* CONFIG_OPT_LIB_FUNCTION */
58 void *memmove(void *v_dst, const void *v_src, __kernel_size_t c)
60 const char *src = v_src;
62 const uint32_t *i_src;
68 /* Use memcpy when source is higher than dest */
70 return memcpy(v_dst, v_src, c);
72 /* The following code tries to optimize the copy by using unsigned
73 * alignment. This will work fine if both source and destination are
74 * aligned on the same boundary. However, if they are aligned on
75 * different boundaries shifts will be necessary. This might result in
76 * bad performance on MicroBlaze systems without a barrel shifter.
78 /* FIXME this part needs more test */
79 /* Do a descending copy - this is a bit trickier! */
84 unsigned value, buf_hold;
86 /* Align the destination to a word boundry. */
87 /* This is done in an endian independant manner. */
89 switch ((unsigned long)dst & 3) {
102 /* Choose a copy scheme based on the source */
103 /* alignment relative to dstination. */
104 switch ((unsigned long)src & 3) {
105 case 0x0: /* Both byte offsets are aligned */
107 i_src = (const void *)src;
109 for (; c >= 4; c -= 4)
112 src = (const void *)i_src;
114 case 0x1: /* Unaligned - Off by 1 */
115 /* Word align the source */
116 i_src = (const void *) (((unsigned)src + 4) & ~3);
118 /* Load the holding buffer */
119 buf_hold = *--i_src >> 24;
121 for (; c >= 4; c -= 4) {
123 *--i_dst = buf_hold << 8 | value;
124 buf_hold = value >> 24;
127 /* Realign the source */
128 src = (const void *)i_src;
131 case 0x2: /* Unaligned - Off by 2 */
132 /* Word align the source */
133 i_src = (const void *) (((unsigned)src + 4) & ~3);
135 /* Load the holding buffer */
136 buf_hold = *--i_src >> 16;
138 for (; c >= 4; c -= 4) {
140 *--i_dst = buf_hold << 16 | value;
141 buf_hold = value >> 16;
144 /* Realign the source */
145 src = (const void *)i_src;
148 case 0x3: /* Unaligned - Off by 3 */
149 /* Word align the source */
150 i_src = (const void *) (((unsigned)src + 4) & ~3);
152 /* Load the holding buffer */
153 buf_hold = *--i_src >> 8;
155 for (; c >= 4; c -= 4) {
157 *--i_dst = buf_hold << 24 | value;
158 buf_hold = value >> 8;
161 /* Realign the source */
162 src = (const void *)i_src;
169 /* simple fast copy, ... unless a cache boundry is crossed */
170 /* Finish off any remaining bytes */
183 #endif /* CONFIG_OPT_LIB_FUNCTION */
184 EXPORT_SYMBOL(memmove);
185 #endif /* __HAVE_ARCH_MEMMOVE */