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- /* $OpenBSD: memcmp.S,v 1.2 2014/11/29 18:51:23 tedu Exp $ */
- /*
- * Written by J.T. Conklin <jtc@netbsd.org>.
- * Public domain.
- */
- #include <machine/asm.h>
- ENTRY(memcmp)
- pushl %edi
- pushl %esi
- movl 12(%esp),%edi
- movl 16(%esp),%esi
- movl 20(%esp),%ecx /* compare by words */
- shrl $2,%ecx
- repe
- cmpsl
- jne L5 /* do we match so far? */
- movl 20(%esp),%ecx /* compare remainder by bytes */
- andl $3,%ecx
- repe
- cmpsb
- jne L6 /* do we match? */
- xorl %eax,%eax /* we match, return zero */
- popl %esi
- popl %edi
- ret
- L5: movl $4,%ecx /* We know that one of the next */
- subl %ecx,%edi /* four pairs of bytes do not */
- subl %ecx,%esi /* match. */
- repe
- cmpsb
- L6: movzbl -1(%edi),%eax /* Perform unsigned comparison */
- movzbl -1(%esi),%edx
- subl %edx,%eax
- popl %esi
- popl %edi
- ret
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