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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 1990, 1991 Sun Microsystems, Inc.
*/
#ident "%Z%%M% %I% %E% SMI"
/*
* Routine to zero out a section of memory (the tail end of the data segment
* upto a page boundary). First nibble off any bytes up to the first double
* aligned word, and then clear doubles until the byte count is zero. Note,
* this assumes the count specified has been rounded to end on a double word
* boundary.
*
* %o0 = addr, %o1 = len
*/
.seg "text"
.global __zero
__zero:
tst %o1 ! Have we any count at all?
ba 3f ! Go find out,
clr %g1 ! but prepare for long loop
! Byte clearing loop
0:
inc %o0 ! Bump address
deccc %o1 ! Decrement count
3:
bz 1f ! If no count left, exit
andcc %o0, 7, %g0 ! Is the address less than double-word aligned?
bnz,a 0b ! Branch if so
clrb [%o0] ! but clear the current byte anyway
! Double clearing loop
2:
std %g0, [%o0] ! Clear next 8 bytes
subcc %o1, 8, %o1 ! Decrement count
bnz 2b ! Branch if any left
inc 8, %o0 ! but always increment address by 8
1:
retl ! Go home
nop
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