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/* $NetBSD: bzero.S,v 1.2 2003/10/06 05:30:21 matt Exp $ */
/* $OpenBSD: bzero.S,v 1.3 2001/06/04 23:14:02 mickey Exp $ */
/*
* (c) Copyright 1988 HEWLETT-PACKARD COMPANY
*
* To anyone who acknowledges that this file is provided "AS IS"
* without any express or implied warranty:
* permission to use, copy, modify, and distribute this file
* for any purpose is hereby granted without fee, provided that
* the above copyright notice and this notice appears in all
* copies, and that the name of Hewlett-Packard Company not be
* used in advertising or publicity pertaining to distribution
* of the software without specific, written prior permission.
* Hewlett-Packard Company makes no representations about the
* suitability of this software for any purpose.
*/
/*
* Copyright (c) 1990,1994 The University of Utah and
* the Computer Systems Laboratory (CSL). All rights reserved.
*
* THE UNIVERSITY OF UTAH AND CSL PROVIDE THIS SOFTWARE IN ITS "AS IS"
* CONDITION, AND DISCLAIM ANY LIABILITY OF ANY KIND FOR ANY DAMAGES
* WHATSOEVER RESULTING FROM ITS USE.
*
* CSL requests users of this software to return to csl-dist@cs.utah.edu any
* improvements that they make and grant CSL redistribution rights.
*
* Utah $Hdr: bzero.s 1.9 94/12/14$
* Author: Bob Wheeler, University of Utah CSL
*/
#include <machine/asm.h>
#ifdef SYSLIBC_SCCS
.text
.asciz "$OpenBSD: bzero.S,v 1.3 2001/06/04 23:14:02 mickey Exp $"
.align 4
#endif
/*
* void
* bzero(dst, count)
* void *dst;
* size_t count;
*/
LEAF_ENTRY(bzero)
comb,>=,n %r0,%arg1,$bzero_exit
/*
* If we need to clear less than a word do it a byte at a time
*/
comib,>>,n 4,%arg1,$bzero_bytes
/*
* Since we are only clearing memory the alignment restrictions
* are simplified. Figure out how many "extra" bytes we need to
* store with stbys.
*/
extru %arg0,31,2,%t1
add %arg1,%t1,%arg1
/*
* We will zero the destination in blocks of 16 bytes as long as we
* can and then we'll go to the 4 byte moves.
*/
comib,>>= 15, %arg1, $bzero_word
addi -16, %arg1, %arg1
$bzero_loop_16:
stbys,b,m %r0,4(%arg0)
stwm %r0,4(%arg0)
stwm %r0,4(%arg0)
stwm %r0,4(%arg0)
comib,<< 15, %arg1, $bzero_loop_16
addi -16, %arg1, %arg1
/*
* see if there is anything left that needs to be zeroed in a word
* move. Since the count was decremented by 16, add 12 to test if
* there are any full word moves left to do.
*/
$bzero_word:
addib,<,n 12,%arg1,$bzero_cleanup
$bzero_loop_4:
addib,>= -4,%arg1,$bzero_loop_4
stbys,b,m %r0,4(%arg0)
/*
* zero the last bytes that may be unaligned on a word boundary
*/
$bzero_cleanup:
addib,=,n 4,%arg1,$bzero_exit
add %arg0,%arg1,%arg0
b $bzero_exit
stbys,e %r0,0(%arg0)
b,n $bzero_exit
/*
* zero by bytes
*/
$bzero_bytes:
addib,> -1,%arg1,$bzero_bytes
stbs,ma %r0,1(%arg0)
$bzero_exit:
bv,n %r0(%rp)
EXIT(bzero)
.end
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