src/multimedia/audio/qaudio_mac_p.h
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     1 /****************************************************************************
       
     2 **
       
     3 ** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
       
     4 ** All rights reserved.
       
     5 ** Contact: Nokia Corporation (qt-info@nokia.com)
       
     6 **
       
     7 ** This file is part of the QtMultimedia module of the Qt Toolkit.
       
     8 **
       
     9 ** $QT_BEGIN_LICENSE:LGPL$
       
    10 ** No Commercial Usage
       
    11 ** This file contains pre-release code and may not be distributed.
       
    12 ** You may use this file in accordance with the terms and conditions
       
    13 ** contained in the Technology Preview License Agreement accompanying
       
    14 ** this package.
       
    15 **
       
    16 ** GNU Lesser General Public License Usage
       
    17 ** Alternatively, this file may be used under the terms of the GNU Lesser
       
    18 ** General Public License version 2.1 as published by the Free Software
       
    19 ** Foundation and appearing in the file LICENSE.LGPL included in the
       
    20 ** packaging of this file.  Please review the following information to
       
    21 ** ensure the GNU Lesser General Public License version 2.1 requirements
       
    22 ** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
       
    23 **
       
    24 ** In addition, as a special exception, Nokia gives you certain additional
       
    25 ** rights.  These rights are described in the Nokia Qt LGPL Exception
       
    26 ** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
       
    27 **
       
    28 ** If you have questions regarding the use of this file, please contact
       
    29 ** Nokia at qt-info@nokia.com.
       
    30 **
       
    31 **
       
    32 **
       
    33 **
       
    34 **
       
    35 **
       
    36 **
       
    37 **
       
    38 ** $QT_END_LICENSE$
       
    39 **
       
    40 ****************************************************************************/
       
    41 
       
    42 //
       
    43 //  W A R N I N G
       
    44 //  -------------
       
    45 //
       
    46 // This file is not part of the Qt API.  It exists for the convenience
       
    47 // of other Qt classes.  This header file may change from version to
       
    48 // version without notice, or even be removed.
       
    49 //
       
    50 // We mean it.
       
    51 //
       
    52 
       
    53 
       
    54 #ifndef QAUDIO_MAC_P_H
       
    55 #define QAUDIO_MAC_P_H
       
    56 
       
    57 #include <CoreAudio/CoreAudio.h>
       
    58 
       
    59 #include <QtCore/qdebug.h>
       
    60 #include <QtCore/qatomic.h>
       
    61 
       
    62 #include <QtMultimedia/qaudioformat.h>
       
    63 
       
    64 QT_BEGIN_HEADER
       
    65 
       
    66 QT_BEGIN_NAMESPACE
       
    67 
       
    68 QT_MODULE(Multimedia)
       
    69 
       
    70 
       
    71 extern QDebug operator<<(QDebug dbg, const QAudioFormat& audioFormat);
       
    72 
       
    73 extern QAudioFormat toQAudioFormat(const AudioStreamBasicDescription& streamFormat);
       
    74 extern AudioStreamBasicDescription toAudioStreamBasicDescription(QAudioFormat const& audioFormat);
       
    75 
       
    76 class QAudioRingBuffer
       
    77 {
       
    78 public:
       
    79     typedef QPair<char*, int> Region;
       
    80 
       
    81     QAudioRingBuffer(int bufferSize);
       
    82     ~QAudioRingBuffer();
       
    83 
       
    84     Region acquireReadRegion(int size)
       
    85     {
       
    86         const int used = m_bufferUsed.fetchAndAddAcquire(0);
       
    87 
       
    88         if (used > 0) {
       
    89             const int readSize = qMin(size, qMin(m_bufferSize - m_readPos, used));
       
    90 
       
    91             return readSize > 0 ? Region(m_buffer + m_readPos, readSize) : Region(0, 0);
       
    92         }
       
    93 
       
    94         return Region(0, 0);
       
    95     }
       
    96 
       
    97     void releaseReadRegion(Region const& region)
       
    98     {
       
    99         m_readPos = (m_readPos + region.second) % m_bufferSize;
       
   100 
       
   101         m_bufferUsed.fetchAndAddRelease(-region.second);
       
   102     }
       
   103 
       
   104     Region acquireWriteRegion(int size)
       
   105     {
       
   106         const int free = m_bufferSize - m_bufferUsed.fetchAndAddAcquire(0);
       
   107 
       
   108         if (free > 0) {
       
   109             const int writeSize = qMin(size, qMin(m_bufferSize - m_writePos, free));
       
   110 
       
   111             return writeSize > 0 ? Region(m_buffer + m_writePos, writeSize) : Region(0, 0);
       
   112         }
       
   113 
       
   114         return Region(0, 0);
       
   115     }
       
   116 
       
   117     void releaseWriteRegion(Region const& region)
       
   118     {
       
   119         m_writePos = (m_writePos + region.second) % m_bufferSize;
       
   120 
       
   121         m_bufferUsed.fetchAndAddRelease(region.second);
       
   122     }
       
   123 
       
   124     int used() const;
       
   125     int free() const;
       
   126     int size() const;
       
   127 
       
   128     void reset();
       
   129 
       
   130 private:
       
   131     int     m_bufferSize;
       
   132     int     m_readPos;
       
   133     int     m_writePos;
       
   134     char*   m_buffer;
       
   135     QAtomicInt  m_bufferUsed;
       
   136 };
       
   137 
       
   138 QT_END_NAMESPACE
       
   139 
       
   140 QT_END_HEADER
       
   141 
       
   142 #endif  // QAUDIO_MAC_P_H
       
   143 
       
   144