forked from dolphin-emu/dolphin
67 lines
1.5 KiB
C++
67 lines
1.5 KiB
C++
// Copyright 2014 Dolphin Emulator Project
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// Licensed under GPLv2
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// Refer to the license.txt file included.
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// Abstraction for a simple flag that can be toggled in a multithreaded way.
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//
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// Simple API:
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// * Set(bool = true): sets the Flag
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// * IsSet(): tests if the flag is set
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// * Clear(): clears the flag (equivalent to Set(false)).
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//
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// More advanced features:
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// * TestAndSet(bool = true): sets the flag to the given value. If a change was
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// needed (the flag did not already have this value)
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// the function returns true. Else, false.
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// * TestAndClear(): alias for TestAndSet(false).
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#pragma once
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#include <atomic>
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namespace Common {
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class Flag final
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{
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public:
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// Declared as explicit since we do not want "= true" to work on a flag
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// object - it should be made explicit that a flag is *not* a normal
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// variable.
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explicit Flag(bool initial_value = false) : m_val(initial_value) {}
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void Set(bool val = true)
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{
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m_val.store(val);
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}
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void Clear()
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{
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Set(false);
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}
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bool IsSet() const
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{
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return m_val.load();
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}
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bool TestAndSet(bool val = true)
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{
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bool expected = !val;
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return m_val.compare_exchange_strong(expected, val);
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}
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bool TestAndClear()
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{
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return TestAndSet(false);
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}
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private:
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// We are not using std::atomic_bool here because MSVC sucks as of VC++
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// 2013 and does not implement the std::atomic_bool(bool) constructor.
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//
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// Re-evaluate next time we upgrade that piece of shit.
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std::atomic<bool> m_val;
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};
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} // namespace Common
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