69 lines
2.7 KiB
C++
69 lines
2.7 KiB
C++
/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef ANDROID_AUDIO_PIPE_H
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#define ANDROID_AUDIO_PIPE_H
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#include "NBAIO.h"
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namespace android {
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// Pipe is multi-thread safe for readers (see PipeReader), but safe for only a single writer thread.
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// It cannot UNDERRUN on write, unless we allow designation of a master reader that provides the
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// time-base. Readers can be added and removed dynamically, and it's OK to have no readers.
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class Pipe : public NBAIO_Sink {
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friend class PipeReader;
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public:
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// maxFrames will be rounded up to a power of 2, and all slots are available. Must be >= 2.
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// buffer is an optional parameter specifying the virtual address of the pipe buffer,
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// which must be of size roundup(maxFrames) * Format_frameSize(format) bytes.
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Pipe(size_t maxFrames, const NBAIO_Format& format, void *buffer = NULL);
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// If a buffer was specified in the constructor, it is not automatically freed by destructor.
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virtual ~Pipe();
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// NBAIO_Port interface
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//virtual ssize_t negotiate(const NBAIO_Format offers[], size_t numOffers,
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// NBAIO_Format counterOffers[], size_t& numCounterOffers);
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//virtual NBAIO_Format format() const;
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// NBAIO_Sink interface
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//virtual int64_t framesWritten() const;
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//virtual int64_t framesUnderrun() const;
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//virtual int64_t underruns() const;
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// The write side of a pipe permits overruns; flow control is the caller's responsibility.
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// It doesn't return +infinity because that would guarantee an overrun.
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virtual ssize_t availableToWrite() const { return mMaxFrames; }
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virtual ssize_t write(const void *buffer, size_t count);
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//virtual ssize_t writeVia(writeVia_t via, size_t total, void *user, size_t block);
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private:
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const size_t mMaxFrames; // always a power of 2
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void * const mBuffer;
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volatile int32_t mRear; // written by android_atomic_release_store
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volatile int32_t mReaders; // number of PipeReader clients currently attached to this Pipe
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const bool mFreeBufferInDestructor;
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};
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} // namespace android
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#endif // ANDROID_AUDIO_PIPE_H
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