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# utils.h Example File

demos/spectrum/app/utils.h

     /****************************************************************************
     **
     ** Copyright (C) 2015 The Qt Company Ltd.
     ** Contact: http://www.qt.io/licensing/
     **
     ** This file is part of the examples of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:BSD$
     ** You may use this file under the terms of the BSD license as follows:
     **
     ** "Redistribution and use in source and binary forms, with or without
     ** modification, are permitted provided that the following conditions are
     ** met:
     **   * Redistributions of source code must retain the above copyright
     **     notice, this list of conditions and the following disclaimer.
     **   * Redistributions in binary form must reproduce the above copyright
     **     notice, this list of conditions and the following disclaimer in
     **     the documentation and/or other materials provided with the
     **     distribution.
     **   * Neither the name of The Qt Company Ltd nor the names of its
     **     contributors may be used to endorse or promote products derived
     **     from this software without specific prior written permission.
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     **
     ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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     #ifndef UTILS_H
     #define UTILS_H

     #include <QtCore/qglobal.h>
     #include <QDebug>

     QT_FORWARD_DECLARE_CLASS(QAudioFormat)

     //-----------------------------------------------------------------------------
     // Miscellaneous utility functions
     //-----------------------------------------------------------------------------

     qint64 audioDuration(const QAudioFormat &format, qint64 bytes);
     qint64 audioLength(const QAudioFormat &format, qint64 microSeconds);

     QString formatToString(const QAudioFormat &format);

     qreal nyquistFrequency(const QAudioFormat &format);

     // Scale PCM value to [-1.0, 1.0]
     qreal pcmToReal(qint16 pcm);

     // Scale real value in [-1.0, 1.0] to PCM
     qint16 realToPcm(qreal real);

     // Check whether the audio format is PCM
     bool isPCM(const QAudioFormat &format);

     // Check whether the audio format is signed, little-endian, 16-bit PCM
     bool isPCMS16LE(const QAudioFormat &format);

     // Compile-time calculation of powers of two

     template<int N> class PowerOfTwo
     { public: static const int Result = PowerOfTwo<N-1>::Result * 2; };

     template<> class PowerOfTwo<0>
     { public: static const int Result = 1; };

     //-----------------------------------------------------------------------------
     // Debug output
     //-----------------------------------------------------------------------------

     class NullDebug
     {
     public:
         template <typename T>
         NullDebug& operator<<(const T&) { return *this; }
     };

     inline NullDebug nullDebug() { return NullDebug(); }

     #ifdef LOG_ENGINE
     #   define ENGINE_DEBUG qDebug()
     #else
     #   define ENGINE_DEBUG nullDebug()
     #endif

     #ifdef LOG_SPECTRUMANALYSER
     #   define SPECTRUMANALYSER_DEBUG qDebug()
     #else
     #   define SPECTRUMANALYSER_DEBUG nullDebug()
     #endif

     #ifdef LOG_WAVEFORM
     #   define WAVEFORM_DEBUG qDebug()
     #else
     #   define WAVEFORM_DEBUG nullDebug()
     #endif

     #endif // UTILS_H