koda@google.com
8b204e9ac0
Prompted by index-out-of-bounds error in old code (bug 18375). BUG=dart:18375 R=iposva@google.com Review URL: https://codereview.chromium.org//247793004 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@35384 260f80e4-7a28-3924-810f-c04153c831b5
42 lines
1.0 KiB
C++
42 lines
1.0 KiB
C++
// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#ifndef VM_RING_BUFFER_H_
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#define VM_RING_BUFFER_H_
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#include "platform/assert.h"
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#include "platform/utils.h"
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namespace dart {
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// Fixed-capacity ring buffer.
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template<typename T, int N>
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class RingBuffer {
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public:
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RingBuffer() : count_(0) { }
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void Add(const T& t) {
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data_[count_++ & kMask] = t;
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}
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// Returns the i'th most recently added element. Requires 0 <= i < Size().
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const T& Get(int i) const {
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ASSERT(0 <= i && i < Size());
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return data_[(count_ - i - 1) & kMask];
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}
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// Returns the number of elements currently stored in this buffer (at most N).
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int Size() const { return Utils::Minimum(count_, static_cast<int64_t>(N)); }
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private:
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static const int kMask = N - 1;
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COMPILE_ASSERT((N & kMask) == 0, N_must_be_power_of_two);
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T data_[N];
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int64_t count_;
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};
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} // namespace dart
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#endif // VM_RING_BUFFER_H_
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