| The Android Open Source Project | 1dc9e47 | 2009-03-03 19:28:35 -0800 | [diff] [blame] | 1 | /* $OpenBSD: memcmp.S,v 1.4 2005/08/07 11:30:38 espie Exp $ */ |
| 2 | /* |
| 3 | * Written by J.T. Conklin <jtc@netbsd.org>. |
| 4 | * Public domain. |
| 5 | */ |
| 6 | |
| 7 | #include <machine/asm.h> |
| 8 | |
| 9 | ENTRY(memcmp) |
| 10 | pushl %edi |
| 11 | pushl %esi |
| 12 | movl 12(%esp),%edi |
| 13 | movl 16(%esp),%esi |
| 14 | cld /* set compare direction forward */ |
| 15 | |
| 16 | movl 20(%esp),%ecx /* compare by words */ |
| 17 | shrl $2,%ecx |
| 18 | repe |
| 19 | cmpsl |
| 20 | jne L5 /* do we match so far? */ |
| 21 | |
| 22 | movl 20(%esp),%ecx /* compare remainder by bytes */ |
| 23 | andl $3,%ecx |
| 24 | repe |
| 25 | cmpsb |
| 26 | jne L6 /* do we match? */ |
| 27 | |
| 28 | xorl %eax,%eax /* we match, return zero */ |
| 29 | popl %esi |
| 30 | popl %edi |
| 31 | ret |
| 32 | |
| 33 | L5: movl $4,%ecx /* We know that one of the next */ |
| 34 | subl %ecx,%edi /* four pairs of bytes do not */ |
| 35 | subl %ecx,%esi /* match. */ |
| 36 | repe |
| 37 | cmpsb |
| 38 | L6: movzbl -1(%edi),%eax /* Perform unsigned comparison */ |
| 39 | movzbl -1(%esi),%edx |
| 40 | subl %edx,%eax |
| 41 | popl %esi |
| 42 | popl %edi |
| 43 | ret |
| Elliott Hughes | 6719500 | 2013-02-13 15:12:32 -0800 | [diff] [blame] | 44 | END(memcmp) |