132 lines
3.9 KiB
C++
132 lines
3.9 KiB
C++
/**
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* Marlin 3D Printer Firmware
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* Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
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*
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* Based on Sprinter and grbl.
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* Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*/
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#pragma once
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#include <stdint.h>
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/**
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* @brief Circular Queue class
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* @details Implementation of the classic ring buffer data structure
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*/
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template<typename T, uint8_t N>
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class CircularQueue {
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private:
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/**
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* @brief Buffer structure
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* @details This structure consolidates all the overhead required to handle
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* a circular queue such as the pointers and the buffer vector.
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*/
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struct buffer_t {
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uint8_t head;
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uint8_t tail;
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uint8_t count;
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uint8_t size;
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T queue[N];
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} buffer;
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public:
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/**
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* @brief Class constructor
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* @details This class requires two template parameters, T defines the type
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* of item this queue will handle and N defines the maximum number of
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* items that can be stored on the queue.
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*/
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CircularQueue<T, N>() {
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buffer.size = N;
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buffer.count = buffer.head = buffer.tail = 0;
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}
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/**
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* @brief Removes and returns a item from the queue
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* @details Removes the oldest item on the queue, pointed to by the
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* buffer_t head field. The item is returned to the caller.
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* @return type T item
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*/
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T dequeue() {
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if (isEmpty()) return T();
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uint8_t index = buffer.head;
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--buffer.count;
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if (++buffer.head == buffer.size)
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buffer.head = 0;
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return buffer.queue[index];
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}
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/**
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* @brief Adds an item to the queue
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* @details Adds an item to the queue on the location pointed by the buffer_t
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* tail variable. Returns false if no queue space is available.
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* @param item Item to be added to the queue
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* @return true if the operation was successful
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*/
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bool enqueue(T const &item) {
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if (isFull()) return false;
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buffer.queue[buffer.tail] = item;
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++buffer.count;
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if (++buffer.tail == buffer.size)
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buffer.tail = 0;
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return true;
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}
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/**
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* @brief Checks if the queue has no items
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* @details Returns true if there are no items on the queue, false otherwise.
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* @return true if queue is empty
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*/
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bool isEmpty() { return buffer.count == 0; }
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/**
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* @brief Checks if the queue is full
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* @details Returns true if the queue is full, false otherwise.
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* @return true if queue is full
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*/
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bool isFull() { return buffer.count == buffer.size; }
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/**
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* @brief Gets the queue size
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* @details Returns the maximum number of items a queue can have.
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* @return the queue size
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*/
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uint8_t size() { return buffer.size; }
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/**
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* @brief Gets the next item from the queue without removing it
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* @details Returns the next item in the queue without removing it
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* or updating the pointers.
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* @return first item in the queue
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*/
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T peek() { return buffer.queue[buffer.head]; }
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/**
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* @brief Gets the number of items on the queue
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* @details Returns the current number of items stored on the queue.
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* @return number of items in the queue
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*/
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uint8_t count() { return buffer.count; }
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};
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