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/*
* Copyright 2017 The Chromium Authors. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#if ENABLE(WEB_AUDIO)
#include "PushPullFIFO.h"
#include "AudioBus.h"
#include <wtf/StdLibExtras.h>
namespace WebCore {
PushPullFIFO::PushPullFIFO(unsigned numberOfChannels, size_t fifoLength)
: m_fifoLength(fifoLength)
{
ASSERT(m_fifoLength <= maxFIFOLength);
m_fifoBus = AudioBus::create(numberOfChannels, m_fifoLength);
}
PushPullFIFO::~PushPullFIFO() = default;
// Push the data from |inputBus| to FIFO. The size of push is determined by
// the length of |inputBus|.
void PushPullFIFO::push(const AudioBus* inputBus)
{
ASSERT(inputBus);
ASSERT(inputBus->length() <= m_fifoLength);
ASSERT(m_indexWrite < m_fifoLength);
const size_t inputBusLength = inputBus->length();
const size_t remainder = m_fifoLength - m_indexWrite;
for (unsigned i = 0; i < m_fifoBus->numberOfChannels(); ++i) {
auto fifoBusChannel = m_fifoBus->channel(i)->mutableSpan();
auto inputBusChannel = inputBus->channel(i)->span();
if (remainder >= inputBusLength) {
// The remainder is big enough for the input data.
memcpySpan(fifoBusChannel.subspan(m_indexWrite), inputBusChannel);
} else {
// The input data overflows the remainder size. Wrap around the index.
memcpySpan(fifoBusChannel.subspan(m_indexWrite), inputBusChannel.first(remainder));
memcpySpan(fifoBusChannel, inputBusChannel.subspan(remainder));
}
}
// Update the write index; wrap it around if necessary.
m_indexWrite = (m_indexWrite + inputBusLength) % m_fifoLength;
// In case of overflow, move the |indexRead| to the updated |indexWrite| to
// avoid reading overwritten frames by the next pull.
if (inputBusLength > m_fifoLength - m_framesAvailable)
m_indexRead = m_indexWrite;
// Update the number of frames available in FIFO.
m_framesAvailable = std::min(m_framesAvailable + inputBusLength, m_fifoLength);
ASSERT(((m_indexRead + m_framesAvailable) % m_fifoLength) == m_indexWrite);
}
// Pull the data out of FIFO to |outputBus|. If remaining frame in the FIFO
// is less than the frames to pull, provides remaining frame plus the silence.
size_t PushPullFIFO::pull(AudioBus* outputBus, size_t framesRequested)
{
ASSERT(outputBus);
ASSERT(framesRequested <= outputBus->length());
ASSERT(framesRequested <= m_fifoLength);
ASSERT(m_indexRead < m_fifoLength);
const size_t remainder = m_fifoLength - m_indexRead;
const size_t framesToFill = std::min(m_framesAvailable, framesRequested);
for (unsigned i = 0; i < m_fifoBus->numberOfChannels(); ++i) {
auto fifoBusChannel = m_fifoBus->channel(i)->span();
auto outputBusChannel = outputBus->channel(i)->mutableSpan();
// Fill up the output bus with the available frames first.
if (remainder >= framesToFill) {
// The remainder is big enough for the frames to pull.
memcpySpan(outputBusChannel, fifoBusChannel.subspan(m_indexRead, framesToFill));
} else {
// The frames to pull is bigger than the remainder size.
// Wrap around the index.
memcpySpan(outputBusChannel, fifoBusChannel.subspan(m_indexRead, remainder));
memcpySpan(outputBusChannel.subspan(remainder), fifoBusChannel.first(framesToFill - remainder));
}
// The frames available was not enough to fulfill the requested frames. Fill
// the rest of the channel with silence.
if (framesRequested > framesToFill)
zeroSpan(outputBusChannel.subspan(framesToFill, framesRequested - framesToFill));
}
// Update the read index; wrap it around if necessary.
m_indexRead = (m_indexRead + framesToFill) % m_fifoLength;
// In case of underflow, move the |indexWrite| to the updated |indexRead|.
if (framesRequested > framesToFill)
m_indexWrite = m_indexRead;
// Update the number of frames in FIFO.
m_framesAvailable -= framesToFill;
ASSERT(((m_indexRead + m_framesAvailable) % m_fifoLength) == m_indexWrite);
// |framesRequested > m_framesAvailable| means the frames in FIFO is not
// enough to fulfill the requested frames from the audio device.
return framesRequested > m_framesAvailable ? framesRequested - m_framesAvailable : 0;
}
unsigned PushPullFIFO::numberOfChannels() const
{
return m_fifoBus->numberOfChannels();
}
} // namespace WebCore
#endif // ENABLE(WEB_AUDIO)
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