third_party/WebKit/Source/platform/audio/PushPullFIFO.h - Issue 2679413003: Revert of Introduce PushPullFIFO class and remove other FIFOs

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Issue 2679413003: Revert of Introduce PushPullFIFO class and remove other FIFOs (Closed)

Patch Set: Created 3 years, 10 months ago

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1 // Copyright 2017 The Chromium Authors. All rights reserved.

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;

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 renders 128 frames (render

28 // quantum, RQ) thus FIFO is needed to handle the general case.

29 class BLINK_PLATFORM_EXPORT PushPullFIFO {

30 USING_FAST_MALLOC(PushPullFIFO);

31 WTF_MAKE_NONCOPYABLE(PushPullFIFO);

32

33 public:

34 // Maximum FIFO length. (512 render quanta)

35 static const size_t kMaxFIFOLength;

36

37 // \|fifoLength\| cannot exceed \|kMaxFIFOLength\|. Otherwise it crashes.

38 explicit PushPullFIFO(unsigned numberOfChannels, size_t fifoLength);

39 ~PushPullFIFO();

40

41 // Pushes the rendered frames by WebAudio engine.

42 // - The \|inputBus\| length is 128 frames (1 render quantum), fixed.

43 // - In case of overflow (FIFO full while push), the existing frames in FIFO

44 // will be overwritten and \|indexRead\| will be forcibly moved to

45 // \|indexWrite\| to avoid reading overwritten frames.

46 void push(const AudioBus* inputBus);

47

48 // Pulling \|framesRequested\| by the audio device thread.

49 // - If \|framesRequested\| is bigger than the length of \|outputBus\|, it

50 // violates SECURITY_CHECK().

51 // - If \|framesRequested\| is bigger than FIFO length, it violates

52 // SECURITY_CHECK().

53 // - In case of underflow (FIFO empty while pull), the remaining space in the

54 // requested output bus will be filled with silence. Thus it will fulfill

55 // the request from the consumer without causing error, but with a glitch.

56 void pull(AudioBus* outputBus, size_t framesRequested);

57

58 size_t framesAvailable() const { return m_framesAvailable; }

59 size_t length() const { return m_fifoLength; }

60 unsigned numberOfChannels() const { return m_fifoBus->numberOfChannels(); }

61 AudioBus* bus() const { return m_fifoBus.get(); }

62

63 // For unit test. Get the current configuration that consists of FIFO length,

64 // number of channels, read/write index position and under/overflow count.

65 const PushPullFIFOStateForTest getStateForTest() const;

66

67 private:

68 // The size of the FIFO.

69 const size_t m_fifoLength = 0;

70

71 RefPtr<AudioBus> m_fifoBus;

72

73 // The number of frames in the FIFO actually available for pulling.

74 size_t m_framesAvailable;

75

76 size_t m_indexRead;

77 size_t m_indexWrite;

78

79 unsigned m_overflowCount;

80 unsigned m_underflowCount;

81 };

82

83 } // namespace blink

84

85 #endif // PushPullFIFO_h

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