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// Copyright 2014 Dolphin Emulator Project
// SPDX-License-Identifier: GPL-2.0-or-later
// Abstraction for a simple flag that can be toggled in a multithreaded way.
//
// Simple API:
// * Set(bool = true): sets the Flag
// * IsSet(): tests if the flag is set
// * Clear(): clears the flag (equivalent to Set(false)).
//
// More advanced features:
// * TestAndSet(bool = true): sets the flag to the given value. If a change was
// needed (the flag did not already have this value)
// the function returns true. Else, false.
// * TestAndClear(): alias for TestAndSet(false).
#pragma once
#include <atomic>
namespace Common
{
class Flag final
{
public:
// Declared as explicit since we do not want "= true" to work on a flag
// object - it should be made explicit that a flag is *not* a normal
// variable.
explicit Flag(bool initial_value = false) : m_val(initial_value) {}
void Set(bool val = true) { m_val.store(val); }
void Clear() { Set(false); }
bool IsSet() const { return m_val.load(); }
bool TestAndSet(bool val = true)
{
bool expected = !val;
return m_val.compare_exchange_strong(expected, val);
}
bool TestAndClear() { return TestAndSet(false); }
private:
std::atomic_bool m_val;
};
} // namespace Common
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