1/* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17#ifndef ANDROID_AUDIO_PIPE_H 18#define ANDROID_AUDIO_PIPE_H 19 20#include <audio_utils/fifo.h> 21#include <media/nbaio/NBAIO.h> 22 23namespace android { 24 25// Pipe is multi-thread safe for readers (see PipeReader), but safe for only a single writer thread. 26// It cannot UNDERRUN on write, unless we allow designation of a master reader that provides the 27// time-base. Readers can be added and removed dynamically, and it's OK to have no readers. 28class Pipe : public NBAIO_Sink { 29 30 friend class PipeReader; 31 32public: 33 // maxFrames will be rounded up to a power of 2, and all slots are available. Must be >= 2. 34 // buffer is an optional parameter specifying the virtual address of the pipe buffer, 35 // which must be of size roundup(maxFrames) * Format_frameSize(format) bytes. 36 Pipe(size_t maxFrames, const NBAIO_Format& format, void *buffer = NULL); 37 38 // If a buffer was specified in the constructor, it is not automatically freed by destructor. 39 virtual ~Pipe(); 40 41 // NBAIO_Port interface 42 43 //virtual ssize_t negotiate(const NBAIO_Format offers[], size_t numOffers, 44 // NBAIO_Format counterOffers[], size_t& numCounterOffers); 45 //virtual NBAIO_Format format() const; 46 47 // NBAIO_Sink interface 48 49 //virtual int64_t framesWritten() const; 50 //virtual int64_t framesUnderrun() const; 51 //virtual int64_t underruns() const; 52 53 // The write side of a pipe permits overruns; flow control is the caller's responsibility. 54 // It doesn't return +infinity because that would guarantee an overrun. 55 virtual ssize_t availableToWrite() { return mMaxFrames; } 56 57 virtual ssize_t write(const void *buffer, size_t count); 58 //virtual ssize_t writeVia(writeVia_t via, size_t total, void *user, size_t block); 59 60private: 61 const size_t mMaxFrames; // always a power of 2 62 void * const mBuffer; 63 audio_utils_fifo mFifo; 64 audio_utils_fifo_writer mFifoWriter; 65 volatile int32_t mReaders; // number of PipeReader clients currently attached to this Pipe 66 const bool mFreeBufferInDestructor; 67}; 68 69} // namespace android 70 71#endif // ANDROID_AUDIO_PIPE_H 72