// Inferno's libkern/memset-arm.s
// http://code.google.com/p/inferno-os/source/browse/libkern/memset-arm.s
//
// Copyright © 1994-1999 Lucent Technologies Inc. All rights reserved.
// Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com). All rights reserved.
// Portions Copyright 2009 The Go Authors. All rights reserved.
//
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// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// THE SOFTWARE.
#include "../../cmd/ld/textflag.h"
TO = 8
TOE = 11
N = 12
TMP = 12 /* N and TMP don't overlap */
TEXT runtime·memclr(SB),NOSPLIT,$0-8
MOVW ptr+0(FP), R(TO)
MOVW n+4(FP), R(N)
MOVW $0, R(0)
ADD R(N), R(TO), R(TOE) /* to end pointer */
CMP $4, R(N) /* need at least 4 bytes to copy */
BLT _1tail
_4align: /* align on 4 */
AND.S $3, R(TO), R(TMP)
BEQ _4aligned
MOVBU.P R(0), 1(R(TO)) /* implicit write back */
B _4align
_4aligned:
SUB $31, R(TOE), R(TMP) /* do 32-byte chunks if possible */
CMP R(TMP), R(TO)
BHS _4tail
MOVW R0, R1 /* replicate */
MOVW R0, R2
MOVW R0, R3
MOVW R0, R4
MOVW R0, R5
MOVW R0, R6
MOVW R0, R7
_f32loop:
CMP R(TMP), R(TO)
BHS _4tail
MOVM.IA.W [R0-R7], (R(TO))
B _f32loop
_4tail:
SUB $3, R(TOE), R(TMP) /* do remaining words if possible */
_4loop:
CMP R(TMP), R(TO)
BHS _1tail
MOVW.P R(0), 4(R(TO)) /* implicit write back */
B _4loop
_1tail:
CMP R(TO), R(TOE)
BEQ _return
MOVBU.P R(0), 1(R(TO)) /* implicit write back */
B _1tail
_return:
RET