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/* $OpenBSD: memset.S,v 1.6 2013/02/02 13:29:14 miod Exp $ */
/*-
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* the Systems Programming Group of the University of Utah Computer
* Science Department.
*
* 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.
*/
#include "DEFS.h"
/*
* This is probably not the best we can do, but it is still much
* faster than the C version in the portable gen directory.
*
* Things that might help:
* - unroll the longword loop (might not be good for a 68020)
* - longword, as opposed to word, align when possible (only on the 68020)
* - use nested DBcc instructions or use one and limit size to 64K
*/
ENTRY(memset)
movl %d2,%sp@-
movl %sp@(8),%a0 | destination
movl %sp@(16),%d0 | count
beq bzdone | nothing to do
movb %sp@(15),%d2 | character
movl %a0,%d1
btst #0,%d1 | address odd?
beq bzeven | no, skip alignment
movb %d2,%a0@+ | set one byte
subql #1,%d0 | adjust count
beq bzdone | if zero, all done
bzeven:
cmpl #15,%d0
ble bzbloop | too small to be worthwhile
clrl %d1 | replicate byte to fill longword
movb %d2,%d1
movl %d1,%d2
lsll #8,%d1
orl %d1,%d2
lsll #8,%d1
orl %d1,%d2
lsll #8,%d1
orl %d1,%d2
movl %d0,%d1 | convert to longword count
lsrl #2,%d1
bzlloop:
movl %d2,%a0@+ | set one longword
subql #1,%d1 | adjust count
bne bzlloop | still more, keep going
andl #3,%d0 | what remains
beq bzdone | nothing, all done
bzbloop:
movb %d2,%a0@+ | set one byte
subql #1,%d0 | adjust count
bne bzbloop | still more, keep going
bzdone:
movl %sp@(8),%d0 | return destination
moveal %d0,%a0
movl %sp@+,%d2
rts
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