A queue struct for tasks.

queue.c

#include "queue.h"

void queue_init(struct queue *q) {
    q->start = 0;
    q->end = 0;
}
uint8_t queue_enqueue(struct queue *q, void (*task)(void*), void *arg) {
    if (queue_full(q))
        return 1;
    q->tasks[q->end] = task;
    q->task_args[q->end++] = arg;
    q->end %= QUEUE_SIZE;
    return 0;
}
uint8_t queue_dequeue(struct queue *q) {
    if (queue_empty(q))
        return 1;
    q->tasks[q->start](q->task_args[q->start++]);
    q->start %= QUEUE_SIZE;
    return 0;
}
uint8_t queue_full(struct queue *q) {
    return ((q->end + 1) % QUEUE_SIZE == q->start);
}
uint8_t queue_empty(struct queue *q) {
    return (q->end == q->start);
}

queue.h

#include <stdint.h>

#ifndef __QUEUE_H__
#define __QUEUE_H__

#define QUEUE_SIZE  (32)

struct queue {
    uint8_t start;
    uint8_t end;
    void (*tasks[QUEUE_SIZE])(void*);   /* Functions to run */
    void *task_args[QUEUE_SIZE];        /* Arguments to function */
};

/*
 * Initialize queue
 *  q: queue struct pointer
 *  Return
 *      None
 */
void queue_init(struct queue *q);

/*
 * Enqueue a task
 *  q: queue struct pointer
 *  task: pointer to function to run
 *  arg: argument to pass to task
 * Return
 *     1: queue is full
 *     0: success
 */
uint8_t queue_enqueue(struct queue *q, void (*task)(void*), void *arg);

/*
 * Run the next task
 *  q: queue struct pointer
 * Return
 *     1: queue is empty
 *     0: success
 */
uint8_t queue_dequeue(struct queue *q);

/*
 * Checks if the queue is full
 *  q: queue struct pointer
 * Return
 *     non-zero: queue is full
 *     0:        queue is not full
 */
uint8_t queue_full(struct queue *q);

/*
 * Checks if the queue is empty
 *  q: queue struct pointer
 * Return
 *     non-zero: queue is empty
 *     0:        queue is not empty
 */
uint8_t queue_empty(struct queue *q);

#endif