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/*
* Copyright (C) 2013 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef ART_RUNTIME_BASE_BOUNDED_FIFO_H_
#define ART_RUNTIME_BASE_BOUNDED_FIFO_H_
namespace art {
// A bounded fifo is a fifo which has a bounded size. The power of two version uses a bit mask to
// avoid needing to deal with wrapping integers around or using a modulo operation.
template <typename T, const size_t MaxSize>
class BoundedFifoPowerOfTwo {
public:
BoundedFifoPowerOfTwo() {
// TODO: Do this with a compile time check.
CHECK(IsPowerOfTwo(MaxSize));
clear();
}
void clear() {
back_index_ = 0;
size_ = 0;
}
bool empty() const {
return size() == 0;
}
size_t size() const {
return size_;
}
void push_back(const T& value) {
++size_;
DCHECK_LE(size_, MaxSize);
// Relies on integer overflow behavior.
data_[back_index_++ & mask_] = value;
}
const T& front() const {
DCHECK_GT(size_, 0U);
return data_[(back_index_ - size_) & mask_];
}
void pop_front() {
DCHECK_GT(size_, 0U);
--size_;
}
private:
static const size_t mask_ = MaxSize - 1;
size_t back_index_, size_;
T data_[MaxSize];
};
} // namespace art
#endif // ART_RUNTIME_BASE_BOUNDED_FIFO_H_
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