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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.
*
* ----------------------------------------------------------------------- */
/*
* memset.S
*
* Reasonably efficient memset, using aligned transfers at least
* for the destination operand.
*/
.globl memset
.type memset,@function
.text
memset:
jecxz 6f
pushl %edi
pushl %ebx
pushl %eax /* Return value */
movl %eax,%edi
movb %dl,%dh
movzwl %dx,%eax
shll $16,%edx
orl %edx,%eax
/* Initial alignment */
movl %edi,%edx
shrl $1,%edx
jnc 1f
stosb
decl %ecx
1:
movb %cl,%bl
cmpl $2,%ecx
jb 3f
shrl $1,%edx
jnc 2f
stosw
subl $2,%ecx
2:
/* Bulk transfer */
movb %cl,%bl
shrl $2,%ecx
rep; stosl
testb $2,%bl
jz 4f
stosw
3:
4:
testb $1,%bl
jz 5f
stosb
5:
popl %eax /* Return value */
popl %ebx
popl %edi
6:
ret
.size memset, .-memset
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