SharedRingBuffer.h revision 5ed503c7a66c90f93759c90237a9b432dbd93f9f 
1/*
2 * Copyright (C) 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 AAUDIO_SHARED_RINGBUFFER_H
18#define AAUDIO_SHARED_RINGBUFFER_H
19
20#include <stdint.h>
21#include <cutils/ashmem.h>
22#include <sys/mman.h>
23
24#include "fifo/FifoBuffer.h"
25#include "RingBufferParcelable.h"
26#include "AudioEndpointParcelable.h"
27
28namespace aaudio {
29
30// Determine the placement of the counters and data in shared memory.
31#define SHARED_RINGBUFFER_READ_OFFSET   0
32#define SHARED_RINGBUFFER_WRITE_OFFSET  sizeof(fifo_counter_t)
33#define SHARED_RINGBUFFER_DATA_OFFSET   (SHARED_RINGBUFFER_WRITE_OFFSET + sizeof(fifo_counter_t))
34
35/**
36 * Atomic FIFO that uses shared memory.
37 */
38class SharedRingBuffer {
39public:
40    SharedRingBuffer() {}
41
42    virtual ~SharedRingBuffer();
43
44    aaudio_result_t allocate(fifo_frames_t bytesPerFrame, fifo_frames_t capacityInFrames);
45
46    void fillParcelable(AudioEndpointParcelable &endpointParcelable,
47                        RingBufferParcelable &ringBufferParcelable);
48
49    FifoBuffer * getFifoBuffer() {
50        return mFifoBuffer;
51    }
52
53private:
54    int            mFileDescriptor = -1;
55    FifoBuffer   * mFifoBuffer = nullptr;
56    uint8_t      * mSharedMemory = nullptr;
57    int32_t        mSharedMemorySizeInBytes = 0;
58    int32_t        mDataMemorySizeInBytes = 0;
59    fifo_frames_t  mCapacityInFrames = 0;
60};
61
62} /* namespace aaudio */
63
64#endif //AAUDIO_SHARED_RINGBUFFER_H
65