40 lines
827 B
ArmAsm
40 lines
827 B
ArmAsm
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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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* Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com>
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*/
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#include <machine/asm.h>
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#if defined(LIBC_SCCS)
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RCSID("$NetBSD: memcmp.S,v 1.2 2007/11/12 18:41:59 ad Exp $")
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#endif
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ENTRY(memcmp)
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movq %rdx,%rcx /* compare by longs */
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shrq $3,%rcx
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repe
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cmpsq
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jne L5 /* do we match so far? */
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movq %rdx,%rcx /* compare remainder by bytes */
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andq $7,%rcx
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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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ret
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L5: movl $8,%ecx /* We know that one of the next */
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subq %rcx,%rdi /* eight pairs of bytes do not */
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subq %rcx,%rsi /* match. */
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repe
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cmpsb
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L6: xorl %eax,%eax /* Perform unsigned comparison */
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movb -1(%rdi),%al
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xorl %edx,%edx
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movb -1(%rsi),%dl
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subl %edx,%eax
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ret
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