87 lines
2.0 KiB
ArmAsm
87 lines
2.0 KiB
ArmAsm
/* ----------------------------------------------------------------------- *
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*
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* Copyright 2008 H. Peter Anvin - All Rights Reserved
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom
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* the Software is furnished to do so, subject to the following
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* conditions:
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*
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* The above copyright notice and this permission notice shall
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* be included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*
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* ----------------------------------------------------------------------- */
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/*
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* memset.S
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*
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* Reasonably efficient memset, using aligned transfers at least
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* for the destination operand.
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*/
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.globl memset
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.type memset,@function
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.text
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memset:
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jecxz 6f
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pushl %edi
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pushl %ebx
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pushl %eax /* Return value */
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movl %eax,%edi
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movb %dl,%dh
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movzwl %dx,%eax
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shll $16,%edx
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orl %edx,%eax
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/* Initial alignment */
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movl %edi,%edx
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shrl $1,%edx
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jnc 1f
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stosb
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decl %ecx
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1:
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movb %cl,%bl
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cmpl $2,%ecx
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jb 3f
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shrl $1,%edx
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jnc 2f
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stosw
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subl $2,%ecx
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2:
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/* Bulk transfer */
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movb %cl,%bl
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shrl $2,%ecx
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rep; stosl
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testb $2,%bl
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jz 4f
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stosw
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3:
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4:
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testb $1,%bl
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jz 5f
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stosb
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5:
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popl %eax /* Return value */
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popl %ebx
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popl %edi
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6:
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ret
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.size memset, .-memset
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