116 lines
3.7 KiB
ArmAsm
116 lines
3.7 KiB
ArmAsm
/* $NetBSD: memset.S,v 1.6 1995/11/28 23:40:56 thorpej Exp $ */
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/*-
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* Copyright (c) 1990 The Regents of the University of California.
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* All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* the Systems Programming Group of the University of Utah Computer
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* Science Department.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include "DEFS.h"
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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RCSID("from: @(#)bzero.s 5.1 (Berkeley) 5/12/90")
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#else
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RCSID("$NetBSD: memset.S,v 1.6 1995/11/28 23:40:56 thorpej Exp $")
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#endif
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#endif /* LIBC_SCCS and not lint */
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/*
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* This is probably not the best we can do, but it is still much
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* faster than the C version in the portable gen directory.
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*
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* Things that might help:
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* - unroll the longword loop (might not be good for a 68020)
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* - longword, as opposed to word, align when possible (only on the 68020)
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* - use nested DBcc instructions or use one and limit size to 64K
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*/
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ENTRY(memset)
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movl d2,sp@-
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movl sp@(8),a0 | destination
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movl sp@(16),d0 | count
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beq bzdone | nothing to do
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movb sp@(15),d2 | character
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movl a0,d1
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btst #0,d1 | address odd?
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beq bzeven | no, skip alignment
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movb d2,a0@+ | set one byte
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subql #1,d0 | adjust count
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beq bzdone | if zero, all done
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bzeven:
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cmpl #15,d0
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ble bzbloop | too small to be worthwhile
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clrl d1 | replicate byte to fill longword
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movb d2,d1
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movl d1,d2
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lsll #8,d1
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orl d1,d2
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lsll #8,d1
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orl d1,d2
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lsll #8,d1
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orl d1,d2
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movl d0,d1 | convert to longword count
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lsrl #2,d1
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#ifdef DEBUG
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moveml #0xffff,sp@-
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movl d2,sp@-
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movl d1,sp@-
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movl d0,sp@-
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movl a0,sp@-
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movl #foo,sp@-
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jsr _printf
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addl #20,sp
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moveml sp@+,#0xffff
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#endif
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bzlloop:
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movl d2,a0@+ | set one longword
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subql #1,d1 | adjust count
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bne bzlloop | still more, keep going
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andl #3,d0 | what remains
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beq bzdone | nothing, all done
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bzbloop:
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movb d2,a0@+ | set one byte
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subql #1,d0 | adjust count
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bne bzbloop | still more, keep going
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bzdone:
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movl sp@(8),d0 | return destination
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movl sp@+,d2
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rts
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#ifdef DEBUG
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.globl _printf
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foo:
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.asciz "a0=%08x d0=%08x d1=%08x d2=%08x\n"
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#endif
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