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/* ----------------------------------------------------------------------- *
*
* Copyright 2008 H. Peter Anvin - All Rights Reserved
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom
* the Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall
* be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* ----------------------------------------------------------------------- */
/*
* memmove.S
*
* Reasonably efficient memmove, using aligned transfers at least
* for the destination operand.
*/
.globl memmove
.type memmove,@function
.text
memmove:
jecxz 3f
pushl %esi
pushl %edi
pushl %eax /* Return value */
movl %eax,%edi
movl %edx,%esi
cmpl %edi,%esi
jb 1f
/* source >= dest, forwards move */
/* Initial alignment */
movl %edi,%edx
shrl $1,%edx
jnc 11f
movsb
decl %ecx
11:
movb %cl,%al
cmpl $2,%ecx
jb 13f
shrl $1,%edx
jnc 12f
movsw
subl $2,%ecx
12:
/* Bulk transfer */
movb %cl,%al
shrl $2,%ecx
rep; movsl
/* Final alignment */
testb $2,%al
jz 14f
movsw
13:
14:
testb $1,%al
jz 15f
movsb
15:
jmp 2f
1:
/* source < dest, backwards move */
std
leal -1(%ecx,%esi),%esi
leal -1(%ecx,%edi),%edi
/* Initial alignment */
movl %edi,%edx
shrl $1,%edx
jnc 21f
movsb
decl %ecx
21:
decl %esi
decl %edi
movb %cl,%al
cmpl $2,%ecx
jb 23f
shrl $1,%edx
jnc 22f
movsw
subl $2,%ecx
22:
/* Bulk transfer */
subl $2,%esi
subl $2,%edi
movb %cl,%al
shrl $2,%ecx
rep; movsl
/* Final alignment */
addl $2,%esi
addl $2,%edi
testb $2,%al
jz 24f
movsw
23:
24:
incl %esi
incl %edi
testb $1,%al
jz 25f
movsb
25:
cld
2:
popl %eax /* Return value */
popl %edi
popl %esi
3:
ret
.size memmove, .-memmove
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