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1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file |
2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
4 | 4 |
5 #ifndef RUNTIME_VM_RING_BUFFER_H_ | 5 #ifndef RUNTIME_VM_RING_BUFFER_H_ |
6 #define RUNTIME_VM_RING_BUFFER_H_ | 6 #define RUNTIME_VM_RING_BUFFER_H_ |
7 | 7 |
8 #include "platform/assert.h" | 8 #include "platform/assert.h" |
9 #include "platform/utils.h" | 9 #include "platform/utils.h" |
10 | 10 |
11 namespace dart { | 11 namespace dart { |
12 | 12 |
13 // Fixed-capacity ring buffer. | 13 // Fixed-capacity ring buffer. |
14 template<typename T, int N> | 14 template <typename T, int N> |
15 class RingBuffer { | 15 class RingBuffer { |
16 public: | 16 public: |
17 RingBuffer() : count_(0) { } | 17 RingBuffer() : count_(0) {} |
18 | 18 |
19 void Add(const T& t) { | 19 void Add(const T& t) { data_[count_++ & kMask] = t; } |
20 data_[count_++ & kMask] = t; | |
21 } | |
22 | 20 |
23 // Returns the i'th most recently added element. Requires 0 <= i < Size(). | 21 // Returns the i'th most recently added element. Requires 0 <= i < Size(). |
24 const T& Get(int i) const { | 22 const T& Get(int i) const { |
25 ASSERT(0 <= i && i < Size()); | 23 ASSERT(0 <= i && i < Size()); |
26 return data_[(count_ - i - 1) & kMask]; | 24 return data_[(count_ - i - 1) & kMask]; |
27 } | 25 } |
28 | 26 |
29 // Returns the number of elements currently stored in this buffer (at most N). | 27 // Returns the number of elements currently stored in this buffer (at most N). |
30 int64_t Size() const { | 28 int64_t Size() const { |
31 return Utils::Minimum(count_, static_cast<int64_t>(N)); | 29 return Utils::Minimum(count_, static_cast<int64_t>(N)); |
32 } | 30 } |
33 | 31 |
34 private: | 32 private: |
35 static const int kMask = N - 1; | 33 static const int kMask = N - 1; |
36 COMPILE_ASSERT((N & kMask) == 0); | 34 COMPILE_ASSERT((N & kMask) == 0); |
37 T data_[N]; | 35 T data_[N]; |
38 int64_t count_; | 36 int64_t count_; |
39 }; | 37 }; |
40 | 38 |
41 } // namespace dart | 39 } // namespace dart |
42 | 40 |
43 #endif // RUNTIME_VM_RING_BUFFER_H_ | 41 #endif // RUNTIME_VM_RING_BUFFER_H_ |
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