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/* $OpenBSD: memmove.S,v 1.3 2009/08/19 19:47:53 miod Exp $ */
/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* 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. 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.
*/
/*
* void *memmove(dst, src, size)
* returns dst
*
* This optimises the usual case (count < 65536) at the expense
* of some extra memory references and branches when count >= 65536.
*/
#include <machine/asm.h>
ENTRY(memmove, R2|R3|R4|R5)
movzwl $65535,r0 /* r0 = 64K (needed below) */
movq 8(ap),r1 /* r1 = src, r2 = length */
movl 4(ap),r3 /* r3 = dst */
cmpl r1,r3
bgtru 1f /* normal forward case */
beql 2f /* equal, nothing to do */
addl2 r2,r1 /* overlaps iff src<dst but src+len>dst */
cmpl r1,r3
bgtru 4f /* overlapping, must move backwards */
subl2 r2,r1
1: /* move forward */
cmpl r2,r0
bgtru 3f /* stupid movc3 limitation */
movc3 r2,(r1),(r3) /* move it all */
2:
movl 4(ap),r0 /* return original dst */
ret
3:
subl2 r0,12(ap) /* adjust length by 64K */
movc3 r0,(r1),(r3) /* move 64K */
movl 12(ap),r2
decw r0 /* from 0 to 65535 */
brb 1b /* retry */
4: /* move backward */
addl2 r2,r3
5:
cmpl r2,r0
bgtru 6f /* stupid movc3 limitation */
subl2 r2,r1
subl2 r2,r3
movc3 r2,(r1),(r3) /* move it all */
movl 4(ap),r0 /* return original dst */
ret
6:
subl2 r0,12(ap) /* adjust length by 64K */
subl2 r0,r1
subl2 r0,r3
movc3 r0,(r1),(r3) /* move 64K */
movl 12(ap),r2
decw r0
subl2 r0,r1
subl2 r0,r3
brb 5b
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