Source/WebCore/platform/audio/cocoa/WebAudioBufferList.cpp

/*
 * Copyright (C) 2017 Apple Inc. All rights reserved.
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#include "config.h"
#include "WebAudioBufferList.h"

#include "CAAudioStreamDescription.h"
#include <wtf/CheckedArithmetic.h>

#include <pal/cf/CoreMediaSoftLink.h>

namespace WebCore {

WebAudioBufferList::WebAudioBufferList(const CAAudioStreamDescription& format)
    : m_bytesPerFrame(format.bytesPerFrame())
    , m_channelCount(format.numberOfInterleavedChannels())
{
    // AudioBufferList is a variable-length struct, so create on the heap with a generic new() operator
    // with a custom size, and initialize the struct manually.
    uint32_t bufferCount = format.numberOfChannelStreams();

    CheckedSize bufferListSize = offsetof(AudioBufferList, mBuffers);
    bufferListSize += CheckedSize { sizeof(AudioBuffer) } * std::max(1U, bufferCount);
    m_listBufferSize = bufferListSize;
    m_canonicalList = std::unique_ptr<AudioBufferList>(static_cast<AudioBufferList*>(::operator new (m_listBufferSize)));
    memset(m_canonicalList.get(), 0, m_listBufferSize);
    m_canonicalList->mNumberBuffers = bufferCount;
    for (uint32_t buffer = 0; buffer < bufferCount; ++buffer)
        m_canonicalList->mBuffers[buffer].mNumberChannels = m_channelCount;

    reset();
}

WebAudioBufferList::WebAudioBufferList(const CAAudioStreamDescription& format, uint32_t sampleCount)
    : WebAudioBufferList(format)
{
    setSampleCount(sampleCount);
}

static inline std::optional<std::pair<size_t, size_t>> computeBufferSizes(uint32_t numberOfInterleavedChannels, uint32_t bytesPerFrame, uint32_t numberOfChannelStreams, uint32_t sampleCount)
{
    size_t totalSampleCount;
    bool result = WTF::safeMultiply(sampleCount, numberOfInterleavedChannels, totalSampleCount);
    if (!result)
        return { };

    size_t bytesPerBuffer;
    result = WTF::safeMultiply(bytesPerFrame, totalSampleCount, bytesPerBuffer);
    if (!result)
        return { };

    size_t flatBufferSize;
    result = WTF::safeMultiply(numberOfChannelStreams, bytesPerBuffer, flatBufferSize);
    if (!result)
        return { };

    return std::make_pair(bytesPerBuffer, flatBufferSize);
}

bool WebAudioBufferList::isSupportedDescription(const CAAudioStreamDescription& format, uint32_t sampleCount)
{
    return !!computeBufferSizes(format.numberOfInterleavedChannels(), format.bytesPerFrame(), format.numberOfChannelStreams(), sampleCount);
}

void WebAudioBufferList::setSampleCount(uint32_t sampleCount)
{
    if (!sampleCount || m_sampleCount == sampleCount)
        return;

    auto bufferSizes = computeBufferSizes(m_channelCount, m_bytesPerFrame, m_canonicalList->mNumberBuffers, sampleCount);
    ASSERT(bufferSizes);
    if (!bufferSizes)
        return;

    m_sampleCount = sampleCount;

    m_flatBuffer.resize(bufferSizes->second);
    auto* data = m_flatBuffer.data();

    for (uint32_t buffer = 0; buffer < m_canonicalList->mNumberBuffers; ++buffer) {
        m_canonicalList->mBuffers[buffer].mData = data;
        m_canonicalList->mBuffers[buffer].mDataByteSize = bufferSizes->first;
        data += bufferSizes->first;
    }

    reset();
}

WebAudioBufferList::WebAudioBufferList(const CAAudioStreamDescription& format, CMSampleBufferRef sampleBuffer)
    : WebAudioBufferList(format)
{
    if (!sampleBuffer)
        return;

    CMBlockBufferRef buffer = nullptr;
    if (noErr == PAL::CMSampleBufferGetAudioBufferListWithRetainedBlockBuffer(sampleBuffer, nullptr, m_canonicalList.get(), m_listBufferSize, kCFAllocatorSystemDefault, kCFAllocatorSystemDefault, kCMSampleBufferFlag_AudioBufferList_Assure16ByteAlignment, &buffer))
        m_blockBuffer = adoptCF(buffer);

    reset();
}

void WebAudioBufferList::reset()
{
    if (!m_list)
        m_list = std::unique_ptr<AudioBufferList>(static_cast<AudioBufferList*>(::operator new (m_listBufferSize)));
    memcpy(m_list.get(), m_canonicalList.get(), m_listBufferSize);
}

IteratorRange<AudioBuffer*> WebAudioBufferList::buffers() const
{
    return WTF::makeIteratorRange(&m_list->mBuffers[0], &m_list->mBuffers[m_list->mNumberBuffers]);
}

uint32_t WebAudioBufferList::bufferCount() const
{
    return m_list->mNumberBuffers;
}

AudioBuffer* WebAudioBufferList::buffer(uint32_t index) const
{
    ASSERT(index < m_list->mNumberBuffers);
    if (index < m_list->mNumberBuffers)
        return &m_list->mBuffers[index];
    return nullptr;
}

void WebAudioBufferList::zeroFlatBuffer()
{
    memset(m_flatBuffer.data(), 0, m_flatBuffer.size());
}

}