NetBSD/lib/libc/arch/m68k/string/memset.S

116 lines
3.7 KiB
ArmAsm

/* $NetBSD: memset.S,v 1.6 1995/11/28 23:40:56 thorpej 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. 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.
*/
#include "DEFS.h"
#if defined(LIBC_SCCS) && !defined(lint)
#if 0
RCSID("from: @(#)bzero.s 5.1 (Berkeley) 5/12/90")
#else
RCSID("$NetBSD: memset.S,v 1.6 1995/11/28 23:40:56 thorpej Exp $")
#endif
#endif /* LIBC_SCCS and not lint */
/*
* 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
#ifdef DEBUG
moveml #0xffff,sp@-
movl d2,sp@-
movl d1,sp@-
movl d0,sp@-
movl a0,sp@-
movl #foo,sp@-
jsr _printf
addl #20,sp
moveml sp@+,#0xffff
#endif
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
movl sp@+,d2
rts
#ifdef DEBUG
.globl _printf
foo:
.asciz "a0=%08x d0=%08x d1=%08x d2=%08x\n"
#endif