blob: 077e81410c9d7bee6f8bf2efc529fd03fbf747db [file] [log] [blame]
// 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.
// func cas(val *int32, old, new int32) bool
// Atomically:
// if *val == old {
// *val = new;
// return true;
// }else
// return false;
TEXT sync┬Ěcas(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
MOVW R0, 16(SP)
RET
fail:
MOVW $0, R0
MOVW R0, 16(SP)
RET