/****************************************************************************
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** Copyright (C) 2012 Digia Plc and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/legal
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** This file is part of the Qt Toolkit.
**
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** accordance with the commercial license agreement provided with the
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** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
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** General Public License version 3.0 as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL included in the
** packaging of this file.  Please review the following information to
** ensure the GNU General Public License version 3.0 requirements will be
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//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists for the convenience
// of other Qt classes.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//


#ifndef QAUDIO_MAC_P_H
#define QAUDIO_MAC_P_H

#include <CoreAudio/CoreAudio.h>

#include <QtCore/qdebug.h>
#include <QtCore/qatomic.h>

#include <qaudioformat.h>

QT_BEGIN_NAMESPACE

extern QAudioFormat toQAudioFormat(const AudioStreamBasicDescription& streamFormat);
extern AudioStreamBasicDescription toAudioStreamBasicDescription(QAudioFormat const& audioFormat);

class QAudioRingBuffer
{
public:
    typedef QPair<char*, int> Region;

    QAudioRingBuffer(int bufferSize);
    ~QAudioRingBuffer();

    Region acquireReadRegion(int size)
    {
        const int used = m_bufferUsed.fetchAndAddAcquire(0);

        if (used > 0) {
            const int readSize = qMin(size, qMin(m_bufferSize - m_readPos, used));

            return readSize > 0 ? Region(m_buffer + m_readPos, readSize) : Region(0, 0);
        }

        return Region(0, 0);
    }

    void releaseReadRegion(Region const& region)
    {
        m_readPos = (m_readPos + region.second) % m_bufferSize;

        m_bufferUsed.fetchAndAddRelease(-region.second);
    }

    Region acquireWriteRegion(int size)
    {
        const int free = m_bufferSize - m_bufferUsed.fetchAndAddAcquire(0);

        if (free > 0) {
            const int writeSize = qMin(size, qMin(m_bufferSize - m_writePos, free));

            return writeSize > 0 ? Region(m_buffer + m_writePos, writeSize) : Region(0, 0);
        }

        return Region(0, 0);
    }

    void releaseWriteRegion(Region const& region)
    {
        m_writePos = (m_writePos + region.second) % m_bufferSize;

        m_bufferUsed.fetchAndAddRelease(region.second);
    }

    int used() const;
    int free() const;
    int size() const;

    void reset();

private:
    int     m_bufferSize;
    int     m_readPos;
    int     m_writePos;
    char*   m_buffer;
    QAtomicInt  m_bufferUsed;
};

QT_END_NAMESPACE

#endif  // QAUDIO_MAC_P_H