Modified https://github.com/KastnerRG/riffa/blob/master/driver/linux/circ_queue.h using kernel built-in circ_buf struct

circ_buf.h

/*
 * Filename: circ_buf.h
 * Version: 1.0
 * Description: A circular buffer using API from 
 * https://github.com/torvalds/linux/blob/master/Documentation/core-api/circular-buffers.rst
 */

#include <linux/circ_buf.h>

// power-of-2 sized buffers
#define CIRC_BUFF_SIZE 8

/**
 * Initializes a circ_queue with depth/length len. Returns non-NULL on success, 
 * NULL if there was a problem creating the queue.
 */
struct circ_buf * init_circ_queue(int len);

/**
 * Pushes a pair of unsigned int values into the specified queue at the head. 
 * Returns 0 on success, non-zero if there is no more space in the queue.
 */
int push_circ_queue(struct circ_buf * q, unsigned int val1, unsigned int val2);

/**
 * Pops a pair of unsigned int values out of the specified queue from the tail.
 * Returns 0 on success, non-zero if the queue is empty.
 */
int pop_circ_queue(struct circ_buf * q, unsigned int * val1, unsigned int * val2);

/**
 * Frees the resources associated with the specified circ_queue.
 */
void free_circ_queue(struct circ_buf * q);