minix/common/lib/libc/arch/x86_64/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

39 lines
827 B
ArmAsm

/*
* Written by J.T. Conklin <jtc@NetBSD.org>.
* Public domain.
* Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com>
*/
#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)
movq %rdx,%rcx /* compare by longs */
shrq $3,%rcx
repe
cmpsq
jne L5 /* do we match so far? */
movq %rdx,%rcx /* compare remainder by bytes */
andq $7,%rcx
repe
cmpsb
jne L6 /* do we match? */
xorl %eax,%eax /* we match, return zero */
ret
L5: movl $8,%ecx /* We know that one of the next */
subq %rcx,%rdi /* eight pairs of bytes do not */
subq %rcx,%rsi /* match. */
repe
cmpsb
L6: xorl %eax,%eax /* Perform unsigned comparison */
movb -1(%rdi),%al
xorl %edx,%edx
movb -1(%rsi),%dl
subl %edx,%eax
ret