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1 // Copyright 2016 The Chromium Authors. All rights reserved. | |
Raymond Toy
2017/01/27 17:39:44
2016 or 2017?
hongchan
2017/01/27 22:39:14
A good question. I'll take 2017.
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2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef PushPullFIFO_h | |
6 #define PushPullFIFO_h | |
7 | |
8 #include "platform/audio/AudioBus.h" | |
9 #include "public/platform/WebCommon.h" | |
10 #include "wtf/Allocator.h" | |
11 | |
12 namespace blink { | |
13 | |
14 // A configuration data container for PushPullFIFO unit test. | |
15 struct PushPullFIFOStateForTest { | |
16 const size_t fifoLength; | |
17 const unsigned numberOfChannels; | |
o1ka
2017/01/27 13:47:54
is "unsigned" a part of WebKit style guide? Chromi
hongchan
2017/01/27 22:39:14
Yes, I have seen it in many files in WebKit.
http
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18 const size_t framesAvailable; | |
19 const size_t indexRead; | |
20 const size_t indexWrite; | |
21 const unsigned overflowCount; | |
22 const unsigned underflowCount; | |
23 }; | |
24 | |
25 // PushPullFIFO class is an intermediate audio sample storage between | |
26 // Blink-WebAudio and the renderer. The renderer's hardware callback buffer size | |
27 // varies on the platform, but the WebAudio always operates by 128 frames of | |
28 // render quantum; thus FIFO is needed. | |
Raymond Toy
2017/01/27 17:39:44
I think there have been quite a few comments on wh
hongchan
2017/01/27 22:39:14
I agree. I will add few constraints in the comment
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29 class BLINK_PLATFORM_EXPORT PushPullFIFO { | |
30 USING_FAST_MALLOC(PushPullFIFO); | |
31 WTF_MAKE_NONCOPYABLE(PushPullFIFO); | |
32 | |
33 public: | |
34 explicit PushPullFIFO(unsigned numberOfChannels, size_t fifoLength); | |
35 ~PushPullFIFO(); | |
36 | |
37 // Pushing audio data is done by the WebAudio render-backing thread. The | |
38 // priority of this thread is lower than the actual audio device thread, | |
39 // thus the thread can be blocked when the audio device thread is pulling | |
40 // data from the FIFO. | |
41 void push(const AudioBus* inputBus); | |
42 | |
43 // Pulling audio data is done by the audio device thread. In the case of | |
44 // underflow, the rest will be filled up with zeros (thus glitches). Pulling | |
45 // an empty FIFO is a valid operation, and the consumer will get a block of | |
46 // silence. | |
47 void pull(AudioBus* outputBus, size_t framesRequested); | |
48 | |
49 size_t framesAvailable() const { return m_framesAvailable; } | |
50 size_t length() const { return m_fifoLength; } | |
51 unsigned numberOfChannels() const { return m_fifoBus->numberOfChannels(); } | |
52 AudioBus* bus() { return m_fifoBus.get(); } | |
o1ka
2017/01/27 13:47:54
const
hongchan
2017/01/27 22:39:14
Done.
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53 | |
54 // For unit test. Get the current configuration that consists of FIFO length, | |
55 // number of channels, read/write index position and under/overflow count. | |
56 const PushPullFIFOStateForTest getStateForTest() const; | |
57 | |
58 private: | |
59 RefPtr<AudioBus> m_fifoBus; | |
60 | |
61 // The size of the FIFO. | |
62 const size_t m_fifoLength = 0; | |
63 | |
64 // The number of frames in the FIFO actually available for pulling. | |
65 size_t m_framesAvailable; | |
66 | |
67 size_t m_indexRead; | |
68 size_t m_indexWrite; | |
69 | |
70 unsigned m_overflowCount; | |
o1ka
2017/01/27 13:47:54
just int? you count up to ~100 only
hongchan
2017/01/27 22:39:14
I am using unsigned for the same reason explained
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71 unsigned m_underflowCount; | |
72 }; | |
73 | |
74 } // namespace blink | |
75 | |
76 #endif // PushPullFIFO_h | |
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