1/*
2 * Copyright (C) 2018 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 SHCIRCULARBUFFER_H
18#define SHCIRCULARBUFFER_H
19
20#include <log/log.h>
21#include <vector>
22
23template <class T>
24class SHCircularBuffer {
25
26public:
27    SHCircularBuffer() : mReadIndex(0), mWriteIndex(0), mReadAvailable(0) {
28    }
29
30    explicit SHCircularBuffer(size_t maxSize) {
31        resize(maxSize);
32    }
33    void resize(size_t maxSize) {
34        mBuffer.resize(maxSize);
35        mReadIndex = 0;
36        mWriteIndex = 0;
37        mReadAvailable = 0;
38    }
39    inline void write(T value) {
40        if (availableToWrite()) {
41            mBuffer[mWriteIndex++] = value;
42            if (mWriteIndex >= getSize()) {
43                mWriteIndex = 0;
44            }
45            mReadAvailable++;
46        } else {
47            ALOGE("Error: SHCircularBuffer no space to write. allocated size %zu ", getSize());
48        }
49    }
50    inline T read() {
51        T value = T();
52        if (availableToRead()) {
53            value = mBuffer[mReadIndex++];
54            if (mReadIndex >= getSize()) {
55                mReadIndex = 0;
56            }
57            mReadAvailable--;
58        } else {
59            ALOGW("Warning: SHCircularBuffer no data available to read. Default value returned");
60        }
61        return value;
62    }
63    inline size_t availableToRead() const {
64        return mReadAvailable;
65    }
66    inline size_t availableToWrite() const {
67        return getSize() - mReadAvailable;
68    }
69    inline size_t getSize() const {
70        return mBuffer.size();
71    }
72
73private:
74    std::vector<T> mBuffer;
75    size_t mReadIndex;
76    size_t mWriteIndex;
77    size_t mReadAvailable;
78};
79
80
81#endif //SHCIRCULARBUFFER_H
82