ConstantSourceNode.cpp   [plain text]

/*
 * Copyright 2016 The Chromium Authors. All rights reserved.
 * Copyright (C) 2020 Apple Inc. All rights reserved.
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#include "config.h"

#if ENABLE(WEB_AUDIO)
#include "ConstantSourceNode.h"

#include "AudioNodeOutput.h"
#include "AudioParam.h"
#include "AudioUtilities.h"
#include "ConstantSourceOptions.h"
#include <wtf/IsoMallocInlines.h>

namespace WebCore {

WTF_MAKE_ISO_ALLOCATED_IMPL(ConstantSourceNode);

ExceptionOr<Ref<ConstantSourceNode>> ConstantSourceNode::create(BaseAudioContext& context, const ConstantSourceOptions& options)
{
    return adoptRef(*new ConstantSourceNode(context, options.offset));
}

ConstantSourceNode::ConstantSourceNode(BaseAudioContext& context, float offset)
    : AudioScheduledSourceNode(context, NodeTypeConstant)
    , m_offset(AudioParam::create(context, "offset"_s, offset, -FLT_MAX, FLT_MAX, AutomationRate::ARate))
    , m_sampleAccurateValues(AudioUtilities::renderQuantumSize)
{
    addOutput(1);
    initialize();
}

ConstantSourceNode::~ConstantSourceNode()
{
    uninitialize();
}

void ConstantSourceNode::process(size_t framesToProcess)
{
    auto& outputBus = *output(0)->bus();
    
    if (!isInitialized() || !outputBus.numberOfChannels()) {
        outputBus.zero();
        return;
    }
    
    size_t quantumFrameOffset = 0;
    size_t nonSilentFramesToProcess = 0;
    double startFrameOffset = 0;
    updateSchedulingInfo(framesToProcess, outputBus, quantumFrameOffset, nonSilentFramesToProcess, startFrameOffset);
    
    if (!nonSilentFramesToProcess) {
        outputBus.zero();
        return;
    }
    
    bool isSampleAccurate = m_offset->hasSampleAccurateValues();
    if (isSampleAccurate && m_offset->automationRate() == AutomationRate::ARate) {
        float* offsets = m_sampleAccurateValues.data();
        m_offset->calculateSampleAccurateValues(offsets, framesToProcess);
        if (nonSilentFramesToProcess > 0) {
            memcpy(outputBus.channel(0)->mutableData() + quantumFrameOffset, offsets + quantumFrameOffset, nonSilentFramesToProcess * sizeof(*offsets));
            outputBus.clearSilentFlag();
        } else
            outputBus.zero();
        return;
    }
    
    float value = isSampleAccurate ? m_offset->finalValue() : m_offset->value();
    if (!value)
        outputBus.zero();
    else {
        float* dest = outputBus.channel(0)->mutableData();
        std::fill_n(dest + quantumFrameOffset, nonSilentFramesToProcess, value);
        outputBus.clearSilentFlag();
    }
}

bool ConstantSourceNode::propagatesSilence() const
{
    return !isPlayingOrScheduled() || hasFinished();
}

} // namespace WebCore

#endif // ENABLE(WEB_AUDIO)