44 lines
850 B
ArmAsm
44 lines
850 B
ArmAsm
/* $OpenBSD: memcmp.S,v 1.4 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(memcmp)
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pushl %edi
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pushl %esi
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movl 12(%esp),%edi
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movl 16(%esp),%esi
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cld /* set compare direction forward */
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movl 20(%esp),%ecx /* compare by words */
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shrl $2,%ecx
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repe
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cmpsl
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jne L5 /* do we match so far? */
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movl 20(%esp),%ecx /* compare remainder by bytes */
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andl $3,%ecx
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repe
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cmpsb
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jne L6 /* do we match? */
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xorl %eax,%eax /* we match, return zero */
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popl %esi
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popl %edi
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ret
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L5: movl $4,%ecx /* We know that one of the next */
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subl %ecx,%edi /* four pairs of bytes do not */
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subl %ecx,%esi /* match. */
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repe
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cmpsb
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L6: movzbl -1(%edi),%eax /* Perform unsigned comparison */
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movzbl -1(%esi),%edx
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subl %edx,%eax
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popl %esi
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popl %edi
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ret
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