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/*
* Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
* Copyright (C) 2008-2009 PetaLogix
* Copyright (C) 2007 John Williams
*
* Reasonably optimised generic C-code for memcpy on Microblaze
* This is generic C code to do efficient, alignment-aware memmove.
*
* It is based on demo code originally Copyright 2001 by Intel Corp, taken from
* http://www.embedded.com/showArticle.jhtml?articleID=19205567
*
* Attempts were made, unsuccessfully, to contact the original
* author of this code (Michael Morrow, Intel). Below is the original
* copyright notice.
*
* This software has been developed by Intel Corporation.
* Intel specifically disclaims all warranties, express or
* implied, and all liability, including consequential and
* other indirect damages, for the use of this program, including
* liability for infringement of any proprietary rights,
* and including the warranties of merchantability and fitness
* for a particular purpose. Intel does not assume any
* responsibility for and errors which may appear in this program
* not any responsibility to update it.
*/
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/compiler.h>
#include <linux/module.h>
#include <linux/string.h>
#ifdef __HAVE_ARCH_MEMMOVE
#ifndef CONFIG_OPT_LIB_FUNCTION
void *memmove(void *v_dst, const void *v_src, __kernel_size_t c)
{
const char *src = v_src;
char *dst = v_dst;
if (!c)
return v_dst;
/* Use memcpy when source is higher than dest */
if (v_dst <= v_src)
return memcpy(v_dst, v_src, c);
/* copy backwards, from end to beginning */
src += c;
dst += c;
/* Simple, byte oriented memmove. */
while (c--)
*--dst = *--src;
return v_dst;
}
#else /* CONFIG_OPT_LIB_FUNCTION */
void *memmove(void *v_dst, const void *v_src, __kernel_size_t c)
{
const char *src = v_src;
char *dst = v_dst;
const uint32_t *i_src;
uint32_t *i_dst;
if (!c)
return v_dst;
/* Use memcpy when source is higher than dest */
if (v_dst <= v_src)
return memcpy(v_dst, v_src, c);
/* The following code tries to optimize the copy by using unsigned
* alignment. This will work fine if both source and destination are
* aligned on the same boundary. However, if they are aligned on
* different boundaries shifts will be necessary. This might result in
* bad performance on MicroBlaze systems without a barrel shifter.
*/
/* FIXME this part needs more test */
/* Do a descending copy - this is a bit trickier! */
dst += c;
src += c;
if (c >= 4) {
unsigned value, buf_hold;
/* Align the destination to a word boundry. */
/* This is done in an endian independant manner. */
switch ((unsigned long)dst & 3) {
case 3:
*--dst = *--src;
--c;
case 2:
*--dst = *--src;
--c;
case 1:
*--dst = *--src;
--c;
}
i_dst = (void *)dst;
/* Choose a copy scheme based on the source */
/* alignment relative to dstination. */
switch ((unsigned long)src & 3) {
case 0x0: /* Both byte offsets are aligned */
i_src = (const void *)src;
for (; c >= 4; c -= 4)
*--i_dst = *--i_src;
src = (const void *)i_src;
break;
case 0x1: /* Unaligned - Off by 1 */
/* Word align the source */
i_src = (const void *) (((unsigned)src + 4) & ~3);
/* Load the holding buffer */
buf_hold = *--i_src >> 24;
for (; c >= 4; c -= 4) {
value = *--i_src;
*--i_dst = buf_hold << 8 | value;
buf_hold = value >> 24;
}
/* Realign the source */
src = (const void *)i_src;
src += 1;
break;
case 0x2: /* Unaligned - Off by 2 */
/* Word align the source */
i_src = (const void *) (((unsigned)src + 4) & ~3);
/* Load the holding buffer */
buf_hold = *--i_src >> 16;
for (; c >= 4; c -= 4) {
value = *--i_src;
*--i_dst = buf_hold << 16 | value;
buf_hold = value >> 16;
}
/* Realign the source */
src = (const void *)i_src;
src += 2;
break;
case 0x3: /* Unaligned - Off by 3 */
/* Word align the source */
i_src = (const void *) (((unsigned)src + 4) & ~3);
/* Load the holding buffer */
buf_hold = *--i_src >> 8;
for (; c >= 4; c -= 4) {
value = *--i_src;
*--i_dst = buf_hold << 24 | value;
buf_hold = value >> 8;
}
/* Realign the source */
src = (const void *)i_src;
src += 3;
break;
}
dst = (void *)i_dst;
}
/* simple fast copy, ... unless a cache boundry is crossed */
/* Finish off any remaining bytes */
switch (c) {
case 4:
*--dst = *--src;
case 3:
*--dst = *--src;
case 2:
*--dst = *--src;
case 1:
*--dst = *--src;
}
return v_dst;
}
#endif /* CONFIG_OPT_LIB_FUNCTION */
EXPORT_SYMBOL(memmove);
#endif /* __HAVE_ARCH_MEMMOVE */
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