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105 lines
2.4 KiB
105 lines
2.4 KiB
/*
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* Copyright (C) 2017 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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#include "RingBuffer.h"
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#include <stdlib.h>
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#include <string.h>
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namespace android {
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RingBuffer::RingBuffer(size_t size)
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: mSize(size),
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mData((sensors_event_t *)malloc(sizeof(sensors_event_t) * mSize)),
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mReadPos(0),
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mWritePos(0) {
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}
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RingBuffer::~RingBuffer() {
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free(mData);
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mData = NULL;
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}
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ssize_t RingBuffer::write(const sensors_event_t *ev, size_t size) {
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Mutex::Autolock autoLock(mLock);
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size_t numAvailableToRead = mWritePos - mReadPos;
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size_t numAvailableToWrite = mSize - numAvailableToRead;
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if (size > numAvailableToWrite) {
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size = numAvailableToWrite;
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}
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size_t writePos = (mWritePos % mSize);
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size_t copy = mSize - writePos;
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if (copy > size) {
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copy = size;
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}
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memcpy(&mData[writePos], ev, copy * sizeof(sensors_event_t));
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if (size > copy) {
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memcpy(mData, &ev[copy], (size - copy) * sizeof(sensors_event_t));
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}
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mWritePos += size;
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if (numAvailableToRead == 0 && size > 0) {
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mNotEmptyCondition.broadcast();
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}
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return size;
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}
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ssize_t RingBuffer::read(sensors_event_t *ev, size_t size) {
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Mutex::Autolock autoLock(mLock);
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size_t numAvailableToRead;
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for (;;) {
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numAvailableToRead = mWritePos - mReadPos;
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if (numAvailableToRead > 0) {
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break;
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}
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mNotEmptyCondition.wait(mLock);
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}
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if (size > numAvailableToRead) {
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size = numAvailableToRead;
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}
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size_t readPos = (mReadPos % mSize);
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size_t copy = mSize - readPos;
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if (copy > size) {
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copy = size;
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}
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memcpy(ev, &mData[readPos], copy * sizeof(sensors_event_t));
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if (size > copy) {
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memcpy(&ev[copy], mData, (size - copy) * sizeof(sensors_event_t));
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}
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mReadPos += size;
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return size;
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}
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} // namespace android
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