1/*
2 * Copyright (C) 2012 Google Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of Apple Inc. ("Apple") nor the names of
14 * its contributors may be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29#ifndef AudioPullFIFO_h
30#define AudioPullFIFO_h
31
32#include "AudioBus.h"
33#include "AudioFIFO.h"
34#include "AudioSourceProvider.h"
35
36namespace WebCore {
37
38// A FIFO (First In First Out) buffer to handle mismatches in buffer sizes between a provider and
39// receiver. The receiver will "pull" data from this FIFO. If data is already available in the
40// FIFO, it is provided to the receiver. If insufficient data is available to satisfy the request,
41// the FIFO will ask the provider for more data when necessary to fulfill a request. Contrast this
42// with a "push" FIFO, where the sender pushes data to the FIFO which will itself push the data to
43// the receiver when the FIFO is full.
44class AudioPullFIFO {
45public:
46 // Create a FIFO that gets data from |provider|. The FIFO will be large enough to hold
47 // |fifoLength| frames of data of |numberOfChannels| channels. The AudioSourceProvider will be
48 // asked to produce |providerSize| frames when the FIFO needs more data.
49 AudioPullFIFO(AudioSourceProvider& audioProvider, unsigned numberOfChannels, size_t fifoLength, size_t providerSize);
50
51 // Read |framesToConsume| frames from the FIFO into the destination. If the FIFO does not have
52 // enough data, we ask the |provider| to get more data to fulfill the request.
53 void consume(AudioBus* destination, size_t framesToConsume);
54
55private:
56 // Fill the FIFO buffer with at least |numberOfFrames| more data.
57 void fillBuffer(size_t numberOfFrames);
58
59 // The provider of the data in our FIFO.
60 AudioSourceProvider& m_provider;
61
62 // The actual FIFO
63 AudioFIFO m_fifo;
64
65 // Number of frames of data that the provider will produce per call.
66 unsigned int m_providerSize;
67
68 // Temporary workspace to hold the data from the provider.
69 RefPtr<AudioBus> m_tempBus;
70};
71
72} // namespace WebCore
73
74#endif // AudioPullFIFO.h
75