| /* $OpenBSD: memcmp.S,v 1.4 2005/08/07 11:30:38 espie 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 |
| cld /* set compare direction forward */ |
| |
| 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 |