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/export.h>
28 #include <linux/types.h>
29 #include <linux/stddef.h>
30 #include <linux/compiler.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 boundary. */
87 /* This is done in an endian independent manner. */
89 switch ((unsigned long)dst & 3) {
104 /* Choose a copy scheme based on the source */
105 /* alignment relative to dstination. */
106 switch ((unsigned long)src & 3) {
107 case 0x0: /* Both byte offsets are aligned */
109 i_src = (const void *)src;
111 for (; c >= 4; c -= 4)
114 src = (const void *)i_src;
116 case 0x1: /* Unaligned - Off by 1 */
117 /* Word align the source */
118 i_src = (const void *) (((unsigned)src + 4) & ~3);
119 #ifndef __MICROBLAZEEL__
120 /* Load the holding buffer */
121 buf_hold = *--i_src >> 24;
123 for (; c >= 4; c -= 4) {
125 *--i_dst = buf_hold << 8 | value;
126 buf_hold = value >> 24;
129 /* Load the holding buffer */
130 buf_hold = (*--i_src & 0xFF) << 24;
132 for (; c >= 4; c -= 4) {
134 *--i_dst = buf_hold |
135 ((value & 0xFFFFFF00) >> 8);
136 buf_hold = (value & 0xFF) << 24;
139 /* Realign the source */
140 src = (const void *)i_src;
143 case 0x2: /* Unaligned - Off by 2 */
144 /* Word align the source */
145 i_src = (const void *) (((unsigned)src + 4) & ~3);
146 #ifndef __MICROBLAZEEL__
147 /* Load the holding buffer */
148 buf_hold = *--i_src >> 16;
150 for (; c >= 4; c -= 4) {
152 *--i_dst = buf_hold << 16 | value;
153 buf_hold = value >> 16;
156 /* Load the holding buffer */
157 buf_hold = (*--i_src & 0xFFFF) << 16;
159 for (; c >= 4; c -= 4) {
161 *--i_dst = buf_hold |
162 ((value & 0xFFFF0000) >> 16);
163 buf_hold = (value & 0xFFFF) << 16;
166 /* Realign the source */
167 src = (const void *)i_src;
170 case 0x3: /* Unaligned - Off by 3 */
171 /* Word align the source */
172 i_src = (const void *) (((unsigned)src + 4) & ~3);
173 #ifndef __MICROBLAZEEL__
174 /* Load the holding buffer */
175 buf_hold = *--i_src >> 8;
177 for (; c >= 4; c -= 4) {
179 *--i_dst = buf_hold << 24 | value;
180 buf_hold = value >> 8;
183 /* Load the holding buffer */
184 buf_hold = (*--i_src & 0xFFFFFF) << 8;
186 for (; c >= 4; c -= 4) {
188 *--i_dst = buf_hold |
189 ((value & 0xFF000000) >> 24);
190 buf_hold = (value & 0xFFFFFF) << 8;
193 /* Realign the source */
194 src = (const void *)i_src;
201 /* simple fast copy, ... unless a cache boundary is crossed */
202 /* Finish off any remaining bytes */
218 #endif /* CONFIG_OPT_LIB_FUNCTION */
219 EXPORT_SYMBOL(memmove);
220 #endif /* __HAVE_ARCH_MEMMOVE */