platform_bionic/libc/arch-x86/string/memcmp.S
Elliott Hughes 851e68a240 Unify our assembler macros.
Our <machine/asm.h> files were modified from upstream, to the extent
that no architecture was actually using the upstream ENTRY or END macros,
assuming that architecture even had such a macro upstream. This patch moves
everyone to the same macros, with just a few tweaks remaining in the
<machine/asm.h> files, which no one should now use directly.

I've removed most of the unused cruft from the <machine/asm.h> files, though
there's still rather a lot in the mips/mips64 ones.

Bug: 12229603
Change-Id: I2fff287dc571ac1087abe9070362fb9420d85d6d
2014-02-20 13:51:26 -08:00

44 lines
869 B
ArmAsm

/* $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 <private/bionic_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
END(memcmp)