1 /* 2 * Copyright 2016 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 FIFO_FIFO_CONTROLLER_INDIRECT_H 18 #define FIFO_FIFO_CONTROLLER_INDIRECT_H 19 20 #include <stdint.h> 21 #include <atomic> 22 23 #include "FifoControllerBase.h" 24 25 namespace android { 26 27 /** 28 * A FifoControllerBase with counters external to the class. 29 * 30 * The actual counters may be stored in separate regions of shared memory 31 * with different access rights. 32 */ 33 class FifoControllerIndirect : public FifoControllerBase { 34 35 public: FifoControllerIndirect(fifo_frames_t capacity,fifo_frames_t threshold,fifo_counter_t * readCounterAddress,fifo_counter_t * writeCounterAddress)36 FifoControllerIndirect(fifo_frames_t capacity, 37 fifo_frames_t threshold, 38 fifo_counter_t * readCounterAddress, 39 fifo_counter_t * writeCounterAddress) 40 : FifoControllerBase(capacity, threshold) 41 , mReadCounterAddress((std::atomic<fifo_counter_t> *) readCounterAddress) 42 , mWriteCounterAddress((std::atomic<fifo_counter_t> *) writeCounterAddress) 43 { 44 setReadCounter(0); 45 setWriteCounter(0); 46 } ~FifoControllerIndirect()47 virtual ~FifoControllerIndirect() {}; 48 49 // TODO review use of memory barriers, probably incorrect getReadCounter()50 virtual fifo_counter_t getReadCounter() override { 51 return mReadCounterAddress->load(std::memory_order_acquire); 52 } 53 setReadCounter(fifo_counter_t count)54 virtual void setReadCounter(fifo_counter_t count) override { 55 mReadCounterAddress->store(count, std::memory_order_release); 56 } 57 getWriteCounter()58 virtual fifo_counter_t getWriteCounter() override { 59 return mWriteCounterAddress->load(std::memory_order_acquire); 60 } 61 setWriteCounter(fifo_counter_t count)62 virtual void setWriteCounter(fifo_counter_t count) override { 63 mWriteCounterAddress->store(count, std::memory_order_release); 64 } 65 66 private: 67 std::atomic<fifo_counter_t> * mReadCounterAddress; 68 std::atomic<fifo_counter_t> * mWriteCounterAddress; 69 }; 70 71 } // android 72 73 #endif //FIFO_FIFO_CONTROLLER_INDIRECT_H 74