portapack-mayhem/firmware/common/circular_buffer.hpp

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/*
* Copyright (C) 2023 Kyle Reed
*
* This file is part of PortaPack.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street,
* Boston, MA 02110-1301, USA.
*/
#ifndef __CIRCULAR_BUFFER_H__
#define __CIRCULAR_BUFFER_H__
#include <stddef.h> // For size_t
#include <memory>
/* Implements a fixed-size, circular buffer.
* NB: Holds Capacity - 1 items.
* There are no bounds checks on accessors so ensure there are
* items in the buffer before accessing front/back/operator[]. */
template <typename T, size_t Capacity>
class CircularBuffer {
public:
CircularBuffer() = default;
CircularBuffer(const CircularBuffer&) = delete;
CircularBuffer(CircularBuffer&&) = delete;
CircularBuffer& operator=(const CircularBuffer&) = delete;
CircularBuffer& operator=(CircularBuffer&&) = delete;
void push_front(T val) {
head_ = head_ > 0 ? head_ - 1 : last_index;
if (head_ == end_)
pop_back_internal();
data_[head_] = std::move(val);
}
void pop_front() {
if (!empty())
pop_front_internal();
}
void push_back(T val) {
data_[end_] = std::move(val);
end_ = end_ < last_index ? end_ + 1 : 0;
if (head_ == end_)
pop_front_internal();
}
void pop_back() {
if (!empty())
pop_back_internal();
}
T& operator[](size_t ix) & {
ix += head_;
if (ix >= Capacity)
ix -= Capacity;
return data_[ix];
}
const T& operator[](size_t ix) const& {
return const_cast<CircularBuffer*>(this)->operator[](ix);
}
const T& front() const& {
return data_[head_];
}
const T& back() const& {
auto end = end_ > 0 ? end_ - 1 : last_index;
return data_[end];
}
size_t size() const& {
auto end = end_;
if (end < head_)
end += Capacity;
return end - head_;
}
bool empty() const {
return head_ == end_;
}
void clear() {
head_ = 0;
end_ = 0;
}
private:
void pop_front_internal() {
head_ = head_ < last_index ? head_ + 1 : 0;
}
void pop_back_internal() {
end_ = end_ > 0 ? end_ - 1 : last_index;
}
static constexpr size_t last_index = Capacity - 1;
size_t head_{0};
size_t end_{0};
T data_[Capacity]{};
};
#endif /*__CIRCULAR_BUFFER_H__*/