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| author | The Android Open Source Project <initial-contribution@android.com> | 2009-03-03 19:28:35 -0800 |
|---|---|---|
| committer | The Android Open Source Project <initial-contribution@android.com> | 2009-03-03 19:28:35 -0800 |
| commit | 1dc9e472e19acfe6dc7f41e429236e7eef7ceda1 (patch) | |
| tree | 3be0c520fae17689bbf5584e1136fb820caef26f /libc/arch-x86/string/memcmp.S | |
| parent | 1767f908af327fa388b1c66883760ad851267013 (diff) | |
| download | bionic-1dc9e472e19acfe6dc7f41e429236e7eef7ceda1.zip bionic-1dc9e472e19acfe6dc7f41e429236e7eef7ceda1.tar.gz bionic-1dc9e472e19acfe6dc7f41e429236e7eef7ceda1.tar.bz2 | |
auto import from //depot/cupcake/@135843
Diffstat (limited to 'libc/arch-x86/string/memcmp.S')
| -rw-r--r-- | libc/arch-x86/string/memcmp.S | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/libc/arch-x86/string/memcmp.S b/libc/arch-x86/string/memcmp.S new file mode 100644 index 0000000..1be189a --- /dev/null +++ b/libc/arch-x86/string/memcmp.S @@ -0,0 +1,43 @@ +/* $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 |