56 lines
1.0 KiB
ArmAsm
56 lines
1.0 KiB
ArmAsm
/* $OpenBSD: memset.S,v 1.3 2005/08/07 11:30:38 espie Exp $ */
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/*
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* Written by J.T. Conklin <jtc@netbsd.org>.
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* Public domain.
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*/
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#include <machine/asm.h>
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ENTRY(memset)
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pushl %edi
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pushl %ebx
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movl 12(%esp),%edi
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movzbl 16(%esp),%eax /* unsigned char, zero extend */
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movl 20(%esp),%ecx
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pushl %edi /* push address of buffer */
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cld /* set fill direction forward */
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/*
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* if the string is too short, it's really not worth the overhead
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* of aligning to word boundries, etc. So we jump to a plain
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* unaligned set.
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*/
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cmpl $0x0f,%ecx
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jle L1
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movb %al,%ah /* copy char to all bytes in word */
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movl %eax,%edx
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sall $16,%eax
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orl %edx,%eax
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movl %edi,%edx /* compute misalignment */
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negl %edx
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andl $3,%edx
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movl %ecx,%ebx
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subl %edx,%ebx
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movl %edx,%ecx /* set until word aligned */
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rep
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stosb
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movl %ebx,%ecx
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shrl $2,%ecx /* set by words */
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rep
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stosl
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movl %ebx,%ecx /* set remainder by bytes */
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andl $3,%ecx
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L1: rep
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stosb
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popl %eax /* pop address of buffer */
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popl %ebx
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popl %edi
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ret
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