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#ifndef MODULATOR_HPP__
#define MODULATOR_HPP__
#include "JS8_Audio/AudioDevice.h"
#include <QAudio>
#include <QPointer>
class SoundOutput;
/**
* Audio device that generates PCM audio frames that encode a message.
*
* Output can be muted while underway, preserving waveform timing when
* transmission is resumed.
*
* This is intended to run in a thread different from the GUI thread.
* It is **not** generally thread-safe, see remarks below.
*/
class Modulator final : public AudioDevice {
Q_OBJECT;
public:
enum class State { Synchronizing, Active, Idle };
// Constructor
explicit Modulator(QObject *parent = nullptr) : AudioDevice{parent} {}
// Inline accessors
/**
* Whether the device is idle.
*
* This method is thread-safe, i.e., can be called from a different thread.
*/
bool isIdle() const { return m_state.load() == State::Idle; }
// Manipulators
void close() override;
/**
* Sets the audio frequency.
*
* This is **not** by itself thread-safe, but ok if fed
* via the Qt signalling mechanism.
*/
Q_SLOT void setAudioFrequency(double const audioFrequency) {
m_audioFrequency = audioFrequency;
}
// Slots
Q_SLOT void start(double audioFrequency, int submode, double tx_delay,
SoundOutput *stream, Channel channel);
Q_SLOT void stop(bool quick = false);
Q_SLOT void tune(bool state = true);
protected:
// QIODevice protocol
qint64 readData(char *, qint64) override;
qint64 writeData(char const *, qint64) override {
return -1; // we don't consume data
}
// In current Qt versions, bytesAvailable() must return a size
// that exceeds some threshold in order for the AudioSink to go
// into Active state and start pulling data. This behavior began
// on Windows with the 6.4 release, on Mac with 6.8, and on Linux
// with 6.9.
//
// See: https://bugreports.qt.io/browse/QTBUG-108672
qint64 bytesAvailable() const override { return 8000; }
private:
// Data members
QPointer<SoundOutput> m_stream;
std::atomic<State> m_state = State::Idle;
bool m_quickClose = false;
bool m_tuning = false;
double m_audioFrequency;
double m_audioFrequency0;
double m_toneSpacing;
double m_phi;
double m_dphi;
double m_amp;
double m_nsps;
qint64 m_silentFrames;
unsigned m_ic;
unsigned m_isym0;
};
#endif
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