1993-05-13 17:51:52 +04:00
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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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#if defined(LIBC_SCCS) && !defined(lint)
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1993-08-01 21:54:45 +04:00
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/*.asciz "from: @(#)bzero.s 5.1 (Berkeley) 5/12/90"*/
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.asciz "$Id: bzero.s,v 1.2 1993/08/01 18:41:39 mycroft Exp $"
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1993-05-13 17:51:52 +04:00
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#endif /* LIBC_SCCS and not lint */
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#include "DEFS.h"
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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(bzero)
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movl sp@(4),a0 /* destination */
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movl sp@(8),d0 /* count */
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jeq bzdone /* nothing to do */
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movl a0,d1
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btst #0,d1 /* address odd? */
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jeq bzeven /* no, skip alignment */
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clrb a0@+ /* yes, clear a byte */
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subql #1,d0 /* adjust count */
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jeq bzdone /* if zero, all done */
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bzeven:
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movl d0,d1
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lsrl #2,d1 /* convert to longword count */
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jeq bzbloop /* no longwords, skip loop */
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bzlloop:
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clrl a0@+ /* clear a longword */
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subql #1,d1 /* adjust count */
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jne bzlloop /* still more, keep going */
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andl #3,d0 /* what remains */
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jeq bzdone /* nothing, all done */
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bzbloop:
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clrb a0@+ /* clear a byte */
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subql #1,d0 /* adjust count */
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jne bzbloop /* still more, keep going */
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bzdone:
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rts
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