1 /*
2  * Copyright (C) 2015 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 RING_BUFFER_H_
18 
19 #define RING_BUFFER_H_
20 
21 #include <media/stagefright/foundation/ABase.h>
22 
23 #include <hardware/sensors.h>
24 #include <utils/threads.h>
25 
26 namespace android {
27 
28 struct RingBuffer {
29     explicit RingBuffer(size_t size);
30     ~RingBuffer();
31 
32     ssize_t write(const sensors_event_t *ev, size_t size);
33     ssize_t read(sensors_event_t *ev, size_t size);
34 
35 private:
36     Mutex mLock;
37     Condition mNotEmptyCondition;
38 
39     size_t mSize;
40     sensors_event_t *mData;
41     size_t mReadPos, mWritePos;
42 
43     DISALLOW_EVIL_CONSTRUCTORS(RingBuffer);
44 };
45 
46 struct LockfreeBuffer {
47     LockfreeBuffer(void* buf, size_t size);
48     ~LockfreeBuffer();
49 
50     // support single writer
51     void write(const sensors_event_t *ev, size_t size);
52 private:
53     sensors_event_t *mData;
54     size_t mSize;
55     size_t mWritePos;
56     int32_t mCounter;
57 
58     DISALLOW_EVIL_CONSTRUCTORS(LockfreeBuffer);
59 };
60 
61 }  // namespace android
62 
63 #endif  // RING_BUFFER_H_
64