1 /* 2 * Copyright (C) 2013 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 #include <pthread.h> 18 19 #include <algorithm> 20 21 #include <log/log.h> 22 23 #include <hardware/sensors.h> 24 #include "SensorEventQueue.h" 25 26 SensorEventQueue::SensorEventQueue(int capacity) { 27 mCapacity = capacity; 28 29 mStart = 0; 30 mSize = 0; 31 mData = new sensors_event_t[mCapacity]; 32 pthread_cond_init(&mSpaceAvailableCondition, NULL); 33 } 34 35 SensorEventQueue::~SensorEventQueue() { 36 delete[] mData; 37 mData = NULL; 38 pthread_cond_destroy(&mSpaceAvailableCondition); 39 } 40 41 int SensorEventQueue::getWritableRegion(int requestedLength, sensors_event_t** out) { 42 if (mSize == mCapacity || requestedLength <= 0) { 43 *out = NULL; 44 return 0; 45 } 46 // Start writing after the last readable record. 47 int firstWritable = (mStart + mSize) % mCapacity; 48 49 int lastWritable = firstWritable + requestedLength - 1; 50 51 // Don't go past the end of the data array. 52 if (lastWritable > mCapacity - 1) { 53 lastWritable = mCapacity - 1; 54 } 55 // Don't go into the readable region. 56 if (firstWritable < mStart && lastWritable >= mStart) { 57 lastWritable = mStart - 1; 58 } 59 *out = &mData[firstWritable]; 60 return lastWritable - firstWritable + 1; 61 } 62 63 void SensorEventQueue::markAsWritten(int count) { 64 mSize += count; 65 } 66 67 int SensorEventQueue::getSize() { 68 return mSize; 69 } 70 71 sensors_event_t* SensorEventQueue::peek() { 72 if (mSize == 0) return NULL; 73 return &mData[mStart]; 74 } 75 76 void SensorEventQueue::dequeue() { 77 if (mSize == 0) return; 78 if (mSize == mCapacity) { 79 pthread_cond_broadcast(&mSpaceAvailableCondition); 80 } 81 mSize--; 82 mStart = (mStart + 1) % mCapacity; 83 } 84 85 // returns true if it waited, or false if it was a no-op. 86 bool SensorEventQueue::waitForSpace(pthread_mutex_t* mutex) { 87 bool waited = false; 88 while (mSize == mCapacity) { 89 waited = true; 90 pthread_cond_wait(&mSpaceAvailableCondition, mutex); 91 } 92 return waited; 93 } 94
