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+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * 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 3 of the License, 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. If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+#pragma once
+
+#include <stdint.h>
+
+/**
+ * @brief Circular Queue class
+ * @details Implementation of the classic ring buffer data structure
+ */
+template<typename T, uint8_t N>
+class CircularQueue {
+ private:
+
+ /**
+ * @brief Buffer structure
+ * @details This structure consolidates all the overhead required to handle
+ * a circular queue such as the pointers and the buffer vector.
+ */
+ struct buffer_t {
+ uint8_t head;
+ uint8_t tail;
+ uint8_t count;
+ uint8_t size;
+ T queue[N];
+ } buffer;
+
+ public:
+ /**
+ * @brief Class constructor
+ * @details This class requires two template parameters, T defines the type
+ * of item this queue will handle and N defines the maximum number of
+ * items that can be stored on the queue.
+ */
+ CircularQueue<T, N>() {
+ buffer.size = N;
+ buffer.count = buffer.head = buffer.tail = 0;
+ }
+
+ /**
+ * @brief Removes and returns a item from the queue
+ * @details Removes the oldest item on the queue, pointed to by the
+ * buffer_t head field. The item is returned to the caller.
+ * @return type T item
+ */
+ T dequeue() {
+ if (isEmpty()) return T();
+
+ uint8_t index = buffer.head;
+
+ --buffer.count;
+ if (++buffer.head == buffer.size)
+ buffer.head = 0;
+
+ return buffer.queue[index];
+ }
+
+ /**
+ * @brief Adds an item to the queue
+ * @details Adds an item to the queue on the location pointed by the buffer_t
+ * tail variable. Returns false if no queue space is available.
+ * @param item Item to be added to the queue
+ * @return true if the operation was successful
+ */
+ bool enqueue(T const &item) {
+ if (isFull()) return false;
+
+ buffer.queue[buffer.tail] = item;
+
+ ++buffer.count;
+ if (++buffer.tail == buffer.size)
+ buffer.tail = 0;
+
+ return true;
+ }
+
+ /**
+ * @brief Checks if the queue has no items
+ * @details Returns true if there are no items on the queue, false otherwise.
+ * @return true if queue is empty
+ */
+ bool isEmpty() { return buffer.count == 0; }
+
+ /**
+ * @brief Checks if the queue is full
+ * @details Returns true if the queue is full, false otherwise.
+ * @return true if queue is full
+ */
+ bool isFull() { return buffer.count == buffer.size; }
+
+ /**
+ * @brief Gets the queue size
+ * @details Returns the maximum number of items a queue can have.
+ * @return the queue size
+ */
+ uint8_t size() { return buffer.size; }
+
+ /**
+ * @brief Gets the next item from the queue without removing it
+ * @details Returns the next item in the queue without removing it
+ * or updating the pointers.
+ * @return first item in the queue
+ */
+ T peek() { return buffer.queue[buffer.head]; }
+
+ /**
+ * @brief Gets the number of items on the queue
+ * @details Returns the current number of items stored on the queue.
+ * @return number of items in the queue
+ */
+ uint8_t count() { return buffer.count; }
+};