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/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "RingBuffer.h"
#include <stdlib.h>
#include <string.h>
namespace android {
RingBuffer::RingBuffer(size_t size)
: mSize(size),
mData((sensors_event_t *)malloc(sizeof(sensors_event_t) * mSize)),
mReadPos(0),
mWritePos(0) {
}
RingBuffer::~RingBuffer() {
free(mData);
mData = NULL;
}
ssize_t RingBuffer::write(const sensors_event_t *ev, size_t size) {
Mutex::Autolock autoLock(mLock);
size_t numAvailableToRead = mWritePos - mReadPos;
size_t numAvailableToWrite = mSize - numAvailableToRead;
if (size > numAvailableToWrite) {
size = numAvailableToWrite;
}
size_t writePos = (mWritePos % mSize);
size_t copy = mSize - writePos;
if (copy > size) {
copy = size;
}
memcpy(&mData[writePos], ev, copy * sizeof(sensors_event_t));
if (size > copy) {
memcpy(mData, &ev[copy], (size - copy) * sizeof(sensors_event_t));
}
mWritePos += size;
if (numAvailableToRead == 0 && size > 0) {
mNotEmptyCondition.broadcast();
}
return size;
}
ssize_t RingBuffer::read(sensors_event_t *ev, size_t size) {
Mutex::Autolock autoLock(mLock);
size_t numAvailableToRead;
for (;;) {
numAvailableToRead = mWritePos - mReadPos;
if (numAvailableToRead > 0) {
break;
}
mNotEmptyCondition.wait(mLock);
}
if (size > numAvailableToRead) {
size = numAvailableToRead;
}
size_t readPos = (mReadPos % mSize);
size_t copy = mSize - readPos;
if (copy > size) {
copy = size;
}
memcpy(ev, &mData[readPos], copy * sizeof(sensors_event_t));
if (size > copy) {
memcpy(&ev[copy], mData, (size - copy) * sizeof(sensors_event_t));
}
mReadPos += size;
return size;
}
} // namespace android
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