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 "NBAIO.h" 21 22 namespace android { 23 24 // Pipe is multi-thread safe for readers (see PipeReader), but safe for only a single writer thread. 25 // It cannot UNDERRUN on write, unless we allow designation of a master reader that provides the 26 // time-base. Readers can be added and removed dynamically, and it's OK to have no readers. 27 class Pipe : public NBAIO_Sink { 28 29 friend class PipeReader; 30 31 public: 32 // maxFrames will be rounded up to a power of 2, and all slots are available. Must be >= 2. 33 // buffer is an optional parameter specifying the virtual address of the pipe buffer, 34 // which must be of size roundup(maxFrames) * Format_frameSize(format) bytes. 35 Pipe(size_t maxFrames, const NBAIO_Format& format, void *buffer = NULL); 36 37 // If a buffer was specified in the constructor, it is not automatically freed by destructor. 38 virtual ~Pipe(); 39 40 // NBAIO_Port interface 41 42 //virtual ssize_t negotiate(const NBAIO_Format offers[], size_t numOffers, 43 // NBAIO_Format counterOffers[], size_t& numCounterOffers); 44 //virtual NBAIO_Format format() const; 45 46 // NBAIO_Sink interface 47 48 //virtual size_t framesWritten() const; 49 //virtual size_t framesUnderrun() const; 50 //virtual size_t underruns() const; 51 52 // The write side of a pipe permits overruns; flow control is the caller's responsibility. 53 // It doesn't return +infinity because that would guarantee an overrun. 54 virtual ssize_t availableToWrite() const { return mMaxFrames; } 55 56 virtual ssize_t write(const void *buffer, size_t count); 57 //virtual ssize_t writeVia(writeVia_t via, size_t total, void *user, size_t block); 58 59 private: 60 const size_t mMaxFrames; // always a power of 2 61 void * const mBuffer; 62 volatile int32_t mRear; // written by android_atomic_release_store 63 volatile int32_t mReaders; // number of PipeReader clients currently attached to this Pipe 64 const bool mFreeBufferInDestructor; 65 }; 66 67 } // namespace android 68 69 #endif // ANDROID_AUDIO_PIPE_H 70
