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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// bool cas(int32 *val, int32 old, int32 new)
// Atomically:
// if(*val == old){
// *val = new;
// return 1;
// }else
// return 0;
TEXT runtime·cas(SB),7,$0
MOVW 0(FP), R1 // *val
MOVW 4(FP), R2 // old
MOVW 8(FP), R3 // new
l:
LDREX (R1), R0
CMP R0, R2
BNE fail
STREX R3, (R1), R0
CMP $0, R0
BNE l
MOVW $1, R0
RET
fail:
MOVW $0, R0
RET
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