forked from Archive/PX4-Autopilot
Simple ring-buffer template class, because re-implementing the wheel in every driver is silly.
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/****************************************************************************
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*
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* Copyright (C) 2013 PX4 Development Team. All rights reserved.
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* Author: Lorenz Meier <lm@inf.ethz.ch>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name PX4 nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/**
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* @file ringbuffer.h
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*
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* A simple ringbuffer template.
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*/
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#pragma once
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template<typename T>
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class RingBuffer {
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public:
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RingBuffer(unsigned size);
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virtual ~RingBuffer();
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/**
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* Put an item into the buffer.
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*
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* @param val Item to put
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* @return true if the item was put, false if the buffer is full
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*/
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bool put(T &val);
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/**
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* Put an item into the buffer.
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*
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* @param val Item to put
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* @return true if the item was put, false if the buffer is full
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*/
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bool put(const T &val);
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/**
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* Get an item from the buffer.
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*
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* @param val Item that was gotten
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* @return true if an item was got, false if the buffer was empty.
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*/
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bool get(T &val);
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/**
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* Get an item from the buffer (scalars only).
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*
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* @return The value that was fetched, or zero if the buffer was
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* empty.
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*/
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T get(void);
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/*
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* Get the number of slots free in the buffer.
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*
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* @return The number of items that can be put into the buffer before
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* it becomes full.
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*/
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unsigned space(void);
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/*
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* Get the number of items in the buffer.
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*
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* @return The number of items that can be got from the buffer before
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* it becomes empty.
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*/
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unsigned count(void);
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/*
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* Returns true if the buffer is empty.
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*/
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bool empty() { return _tail == _head; }
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/*
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* Returns true if the buffer is full.
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*/
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bool full() { return _next(_head) == _tail; }
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private:
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T *const _buf;
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const unsigned _size;
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volatile unsigned _head; /**< insertion point */
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volatile unsigned _tail; /**< removal point */
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unsigned _next(unsigned index);
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};
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template <typename T>
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RingBuffer<T>::RingBuffer(unsigned size) :
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_buf(new T[size + 1]),
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_size(size),
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_head(size),
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_tail(size)
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{}
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template <typename T>
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RingBuffer<T>::~RingBuffer()
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{
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if (_buf != nullptr)
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delete[] _buf;
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}
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template <typename T>
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bool RingBuffer<T>::put(T &val)
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{
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unsigned next = _next(_head);
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if (next != _tail) {
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_buf[_head] = val;
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_head = next;
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return true;
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} else {
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return false;
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}
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}
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template <typename T>
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bool RingBuffer<T>::put(const T &val)
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{
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unsigned next = _next(_head);
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if (next != _tail) {
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_buf[_head] = val;
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_head = next;
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return true;
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} else {
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return false;
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}
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}
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template <typename T>
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bool RingBuffer<T>::get(T &val)
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{
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if (_tail != _head) {
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val = _buf[_tail];
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_tail = _next(_tail);
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return true;
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} else {
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return false;
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}
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}
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template <typename T>
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T RingBuffer<T>::get(void)
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{
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T val;
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return get(val) ? val : 0;
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}
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template <typename T>
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unsigned RingBuffer<T>::space(void)
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{
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return (_tail >= _head) ? (_size - (_tail - _head)) : (_head - _tail - 1);
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}
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template <typename T>
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unsigned RingBuffer<T>::count(void)
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{
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return _size - space();
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}
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template <typename T>
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unsigned RingBuffer<T>::_next(unsigned index)
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{
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return (0 == index) ? _size : (index - 1);
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}
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