OscillatorNode.h   [plain text]

/*
 * Copyright (C) 2012, Google Inc. All rights reserved.
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#pragma once

#include "AudioScheduledSourceNode.h"
#include "OscillatorOptions.h"
#include "OscillatorType.h"
#include <wtf/Lock.h>

namespace WebCore {

class PeriodicWave;

// OscillatorNode is an audio generator of periodic waveforms.

class OscillatorNode : public AudioScheduledSourceNode {
    WTF_MAKE_ISO_ALLOCATED(OscillatorNode);
public:
    static ExceptionOr<Ref<OscillatorNode>> create(BaseAudioContext&, const OscillatorOptions& = { });

    virtual ~OscillatorNode();

    const char* activeDOMObjectName() const override { return "OscillatorNode"; }

    OscillatorType type() const { return m_type; }
    ExceptionOr<void> setType(OscillatorType);

    AudioParam* frequency() { return m_frequency.get(); }
    AudioParam* detune() { return m_detune.get(); }

    void setPeriodicWave(PeriodicWave&);

protected:
    explicit OscillatorNode(BaseAudioContext&, const OscillatorOptions& = { });

private:
    void process(size_t framesToProcess) final;

    double tailTime() const final { return 0; }
    double latencyTime() const final { return 0; }

    // Returns true if there are sample-accurate timeline parameter changes.
    bool calculateSampleAccuratePhaseIncrements(size_t framesToProcess);

    double processARate(int, float* destP, double virtualReadIndex, float* phaseIncrements);
    double processKRate(int, float* destP, double virtualReadIndex);

    bool propagatesSilence() const final;

    // One of the waveform types defined in the enum.
    OscillatorType m_type;
    
    // Frequency value in Hertz.
    RefPtr<AudioParam> m_frequency;

    // Detune value (deviating from the frequency) in Cents.
    RefPtr<AudioParam> m_detune;

    bool m_firstRender { true };

    // m_virtualReadIndex is a sample-frame index into our buffer representing the current playback position.
    // Since it's floating-point, it has sub-sample accuracy.
    double m_virtualReadIndex { 0 };

    // This synchronizes process().
    mutable Lock m_processLock;

    // Stores sample-accurate values calculated according to frequency and detune.
    AudioFloatArray m_phaseIncrements;
    AudioFloatArray m_detuneValues;
    
    RefPtr<PeriodicWave> m_periodicWave;
};

String convertEnumerationToString(OscillatorType); // In JSOscillatorNode.cpp

} // namespace WebCore

namespace WTF {

template<> struct LogArgument<WebCore::OscillatorType> {
    static String toString(WebCore::OscillatorType type) { return convertEnumerationToString(type); }
};

} // namespace WTF