| // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| #ifndef RUNTIME_VM_RING_BUFFER_H_ |
| #define RUNTIME_VM_RING_BUFFER_H_ |
| |
| #include "platform/assert.h" |
| #include "platform/utils.h" |
| |
| namespace dart { |
| |
| // Fixed-capacity ring buffer. |
| template <typename T, int N> |
| class RingBuffer { |
| public: |
| RingBuffer() : count_(0) {} |
| |
| void Add(const T& t) { data_[count_++ & kMask] = t; } |
| |
| // Returns the i'th most recently added element. Requires 0 <= i < Size(). |
| const T& Get(int i) const { |
| ASSERT(0 <= i && i < Size()); |
| return data_[(count_ - i - 1) & kMask]; |
| } |
| |
| // Returns the number of elements currently stored in this buffer (at most N). |
| int64_t Size() const { |
| return Utils::Minimum(count_, static_cast<int64_t>(N)); |
| } |
| |
| private: |
| static const int kMask = N - 1; |
| COMPILE_ASSERT((N & kMask) == 0); |
| T data_[N]; |
| int64_t count_; |
| }; |
| |
| } // namespace dart |
| |
| #endif // RUNTIME_VM_RING_BUFFER_H_ |