freebsd-nq/lib/libc/i386/string/memmove.S
David Greenman aacd7f348e Be smarter about handling overlapped copies and only go backwards if it
is really necessary. Going backwards on a P6 is much slower than forwards
and it's a little slower on a P5. Also moved the count mask and 'std'
down a few lines - it's a couple percent faster this way on a P5.
1995-12-27 18:47:45 +00:00

93 lines
2.8 KiB
ArmAsm

/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $Id: memmove.S,v 1.2 1995/01/23 01:29:02 davidg Exp $
*/
#if defined(LIBC_RCS) && !defined(lint)
.text
.asciz "$Id: memmove.S,v 1.2 1995/01/23 01:29:02 davidg Exp $"
#endif /* LIBC_RCS and not lint */
#include "DEFS.h"
/*
* (ov)bcopy (src,dst,cnt)
* ws@tools.de (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
*/
ALTENTRY(memcpy)
ENTRY(memmove)
pushl %esi
pushl %edi
movl 12(%esp),%edi
movl 16(%esp),%esi
movl 20(%esp),%ecx
movl %edi,%eax
subl %esi,%eax
cmpl %ecx,%eax
jb 1f
cld /* nope, copy forwards. */
shrl $2,%ecx /* copy by words */
rep
movsl
movl 20(%esp),%ecx
andl $3,%ecx /* any bytes left? */
rep
movsb
movl 12(%esp),%eax
popl %edi
popl %esi
ret
1:
addl %ecx,%edi /* copy backwards. */
addl %ecx,%esi
decl %edi
decl %esi
andl $3,%ecx /* any fractional bytes? */
std
rep
movsb
movl 20(%esp),%ecx /* copy remainder by words */
shrl $2,%ecx
subl $3,%esi
subl $3,%edi
rep
movsl
movl 12(%esp),%eax
popl %edi
popl %esi
cld
ret