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// |reftest| skip-if(!this.hasOwnProperty('Atomics')||!this.hasOwnProperty('SharedArrayBuffer')||(this.hasOwnProperty('getBuildConfiguration')&&getBuildConfiguration('arm64-simulator'))) -- Atomics,SharedArrayBuffer is not enabled unconditionally, ARM64 Simulator cannot emulate atomics
// Copyright (C) 2018 Rick Waldron. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
esid: sec-atomics.compareExchange
description: >
Atomics.compareExchange returns the value that existed at the
index prior to the operation.
info: |
Atomics.compareExchange( typedArray, index, expectedValue, replacementValue )
...
12. Let compareExchange denote a semantic function of two List of
byte values arguments that returns the second argument if the
first argument is element-wise equal to expectedBytes.
13. Return GetModifySetValueInBuffer(buffer, indexedPosition,
elementType, replacement, compareExchange).
GetModifySetValueInBuffer( arrayBuffer,
byteIndex, type, value, op [ , isLittleEndian ] )
...
16. Return RawBytesToNumber(type, rawBytesRead, isLittleEndian).
features: [Atomics, SharedArrayBuffer, TypedArray]
---*/
const buffer = new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4);
const i32a = new Int32Array(buffer);
const update = 0b00000001000000001000000010000001;
i32a[0] = update;
assert.sameValue(
Atomics.compareExchange(i32a, 0, update, 0),
update,
'Atomics.compareExchange(i32a, 0, update, 0) returns the value of `update` (0b00000001000000001000000010000001)'
);
assert.sameValue(i32a[0], 0, 'The value of i32a[0] is 0');
reportCompare(0, 0);
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