/****************************************************************************
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** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
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** This file is part of the QtCore module of the Qt Toolkit.
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** Alternatively, this file may be used under the terms of the GNU General
** Public License version 3.0 as published by the Free Software Foundation
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****************************************************************************/

#ifndef QREFCOUNT_H
#define QREFCOUNT_H

#include <QtCore/qatomic.h>

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE


namespace QtPrivate
{

class RefCount
{
public:
    inline bool ref() {
        int count = atomic.load();
        if (count == 0) // !isSharable
            return false;
        if (count != -1) // !isStatic
            atomic.ref();
        return true;
    }

    inline bool deref() {
        int count = atomic.load();
        if (count == 0) // !isSharable
            return false;
        if (count == -1) // isStatic
            return true;
        return atomic.deref();
    }

    bool setSharable(bool sharable)
    {
        Q_ASSERT(!isShared());
        if (sharable)
            return atomic.testAndSetRelaxed(0, 1);
        else
            return atomic.testAndSetRelaxed(1, 0);
    }

    bool isStatic() const
    {
        // Persistent object, never deleted
        return atomic.load() == -1;
    }

    bool isSharable() const
    {
        // Sharable === Shared ownership.
        return atomic.load() != 0;
    }

    bool isShared() const
    {
        int count = atomic.load();
        return (count != 1) && (count != 0);
    }

    void initializeOwned() { atomic.store(1); }
    void initializeUnsharable() { atomic.store(0); }

    QBasicAtomicInt atomic;
};

}

#define Q_REFCOUNT_INITIALIZE_STATIC { Q_BASIC_ATOMIC_INITIALIZER(-1) }

QT_END_NAMESPACE

QT_END_HEADER

#endif