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 <android-base/unique_fd.h>
21 #include <stdint.h>
22 #include <cutils/ashmem.h>
23 #include <sys/mman.h>
24 
25 #include "fifo/FifoBuffer.h"
26 #include "binding/RingBufferParcelable.h"
27 #include "binding/AudioEndpointParcelable.h"
28 
29 namespace aaudio {
30 
31 // Determine the placement of the counters and data in shared memory.
32 #define SHARED_RINGBUFFER_READ_OFFSET   0
33 #define SHARED_RINGBUFFER_WRITE_OFFSET  sizeof(fifo_counter_t)
34 #define SHARED_RINGBUFFER_DATA_OFFSET   (SHARED_RINGBUFFER_WRITE_OFFSET + sizeof(fifo_counter_t))
35 
36 /**
37  * Atomic FIFO that uses shared memory.
38  */
39 class SharedRingBuffer {
40 public:
SharedRingBuffer()41     SharedRingBuffer() {}
42 
43     virtual ~SharedRingBuffer();
44 
45     aaudio_result_t allocate(android::fifo_frames_t bytesPerFrame, android::fifo_frames_t capacityInFrames);
46 
47     void fillParcelable(AudioEndpointParcelable &endpointParcelable,
48                         RingBufferParcelable &ringBufferParcelable);
49 
getFifoBuffer()50     android::FifoBuffer * getFifoBuffer() {
51         return mFifoBuffer;
52     }
53 
54 private:
55     android::base::unique_fd  mFileDescriptor;
56     android::FifoBuffer      *mFifoBuffer = nullptr;
57     uint8_t                  *mSharedMemory = nullptr;
58     int32_t                   mSharedMemorySizeInBytes = 0;
59     int32_t                   mDataMemorySizeInBytes = 0;
60     android::fifo_frames_t    mCapacityInFrames = 0;
61 };
62 
63 } /* namespace aaudio */
64 
65 #endif //AAUDIO_SHARED_RINGBUFFER_H
66