minix/common/lib/libc/arch/i386/string/memcmp.S
Gianluca Guida b6cbf7203b Import unmodified NetBSD libc in trunk
This patch imports the unmodified current version of NetBSD libc.
The NetBSD includes are in /nbsd_include, while the libc code itself is 
split between lib/nbsd_libc and common/lib/libc.
2011-02-14 19:36:03 +00:00

48 lines
865 B
ArmAsm

/*
* Written by J.T. Conklin <jtc@NetBSD.org>.
* Public domain.
*/
#include <machine/asm.h>
#if defined(LIBC_SCCS)
RCSID("$NetBSD: memcmp.S,v 1.2 2007/11/12 18:41:59 ad Exp $")
#endif
ENTRY(memcmp)
pushl %edi
pushl %esi
movl 12(%esp),%edi
movl 16(%esp),%esi
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: xorl %eax,%eax /* Perform unsigned comparison */
movb -1(%edi),%al
xorl %edx,%edx
movb -1(%esi),%dl
subl %edx,%eax
popl %esi
popl %edi
ret