Annotation of sys/lib/libkern/arch/i386/memcmp.S, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: memcmp.S,v 1.1 2000/06/16 19:56:54 millert Exp $ */
2:
3: /*
4: * Written by J.T. Conklin <jtc@netbsd.org>.
5: * Public domain.
6: */
7:
8: #include <machine/asm.h>
9:
10: ENTRY(memcmp)
11: pushl %edi
12: pushl %esi
13: movl 12(%esp),%edi
14: movl 16(%esp),%esi
15: cld /* set compare direction forward */
16:
17: movl 20(%esp),%ecx /* compare by words */
18: shrl $2,%ecx
19: repe
20: cmpsl
21: jne L5 /* do we match so far? */
22:
23: movl 20(%esp),%ecx /* compare remainder by bytes */
24: andl $3,%ecx
25: repe
26: cmpsb
27: jne L6 /* do we match? */
28:
29: xorl %eax,%eax /* we match, return zero */
30: popl %esi
31: popl %edi
32: ret
33:
34: L5: movl $4,%ecx /* We know that one of the next */
35: subl %ecx,%edi /* four pairs of bytes do not */
36: subl %ecx,%esi /* match. */
37: repe
38: cmpsb
39: L6: movzbl -1(%edi),%eax /* Perform unsigned comparison */
40: movzbl -1(%esi),%edx
41: subl %edx,%eax
42: popl %esi
43: popl %edi
44: ret
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