source: trunk/src/multimedia/audio/qaudio_mac_p.h

/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation ([email protected])
**
** This file is part of the QtMultimedia module of the Qt Toolkit.
**
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** accordance with the Qt Commercial License Agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and Nokia.
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** GNU Lesser General Public License Usage
** 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
** packaging of this file.  Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
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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 <QtMultimedia/qaudioformat.h>

QT_BEGIN_HEADER

QT_BEGIN_NAMESPACE

QT_MODULE(Multimedia)


extern QDebug operator<<(QDebug dbg, const QAudioFormat& audioFormat);

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

QT_END_HEADER

#endif  // QAUDIO_MAC_P_H