1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
|
/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ANDROID_AUDIO_PIPE_H
#define ANDROID_AUDIO_PIPE_H
#include "NBAIO.h"
namespace android {
// Pipe is multi-thread safe for readers (see PipeReader), but safe for only a single writer thread.
// It cannot UNDERRUN on write, unless we allow designation of a master reader that provides the
// time-base. Readers can be added and removed dynamically, and it's OK to have no readers.
class Pipe : public NBAIO_Sink {
friend class PipeReader;
public:
// maxFrames will be rounded up to a power of 2, and all slots are available. Must be >= 2.
// buffer is an optional parameter specifying the virtual address of the pipe buffer,
// which must be of size roundup(maxFrames) * Format_frameSize(format) bytes.
Pipe(size_t maxFrames, const NBAIO_Format& format, void *buffer = NULL);
// If a buffer was specified in the constructor, it is not automatically freed by destructor.
virtual ~Pipe();
// NBAIO_Port interface
//virtual ssize_t negotiate(const NBAIO_Format offers[], size_t numOffers,
// NBAIO_Format counterOffers[], size_t& numCounterOffers);
//virtual NBAIO_Format format() const;
// NBAIO_Sink interface
//virtual size_t framesWritten() const;
//virtual size_t framesUnderrun() const;
//virtual size_t underruns() const;
// The write side of a pipe permits overruns; flow control is the caller's responsibility.
// It doesn't return +infinity because that would guarantee an overrun.
virtual ssize_t availableToWrite() const { return mMaxFrames; }
virtual ssize_t write(const void *buffer, size_t count);
//virtual ssize_t writeVia(writeVia_t via, size_t total, void *user, size_t block);
private:
const size_t mMaxFrames; // always a power of 2
void * const mBuffer;
volatile int32_t mRear; // written by android_atomic_release_store
volatile int32_t mReaders; // number of PipeReader clients currently attached to this Pipe
const bool mFreeBufferInDestructor;
};
} // namespace android
#endif // ANDROID_AUDIO_PIPE_H
|
