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// 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_