Fairphone ODM | 25c12f5 | 2023-12-15 17:24:06 +0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2013 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 ART_LIBARTBASE_BASE_BOUNDED_FIFO_H_ |
| 18 | #define ART_LIBARTBASE_BASE_BOUNDED_FIFO_H_ |
| 19 | |
| 20 | #include <android-base/logging.h> |
| 21 | |
| 22 | #include "bit_utils.h" |
| 23 | |
| 24 | namespace art { |
| 25 | |
| 26 | // A bounded fifo is a fifo which has a bounded size. The power of two version uses a bit mask to |
| 27 | // avoid needing to deal with wrapping integers around or using a modulo operation. |
| 28 | template <typename T, const size_t kMaxSize> |
| 29 | class BoundedFifoPowerOfTwo { |
| 30 | static_assert(IsPowerOfTwo(kMaxSize), "kMaxSize must be a power of 2."); |
| 31 | |
| 32 | public: |
| 33 | BoundedFifoPowerOfTwo() { |
| 34 | clear(); |
| 35 | } |
| 36 | |
| 37 | void clear() { |
| 38 | back_index_ = 0; |
| 39 | size_ = 0; |
| 40 | } |
| 41 | |
| 42 | bool empty() const { |
| 43 | return size() == 0; |
| 44 | } |
| 45 | |
| 46 | size_t size() const { |
| 47 | return size_; |
| 48 | } |
| 49 | |
| 50 | void push_back(const T& value) { |
| 51 | ++size_; |
| 52 | DCHECK_LE(size_, kMaxSize); |
| 53 | // Relies on integer overflow behavior. |
| 54 | data_[back_index_++ & mask_] = value; |
| 55 | } |
| 56 | |
| 57 | const T& front() const { |
| 58 | DCHECK_GT(size_, 0U); |
| 59 | return data_[(back_index_ - size_) & mask_]; |
| 60 | } |
| 61 | |
| 62 | void pop_front() { |
| 63 | DCHECK_GT(size_, 0U); |
| 64 | --size_; |
| 65 | } |
| 66 | |
| 67 | private: |
| 68 | static const size_t mask_ = kMaxSize - 1; |
| 69 | size_t back_index_, size_; |
| 70 | T data_[kMaxSize]; |
| 71 | }; |
| 72 | |
| 73 | } // namespace art |
| 74 | |
| 75 | #endif // ART_LIBARTBASE_BASE_BOUNDED_FIFO_H_ |