hjg

void queue_init(queue *q)
{
    q->head = 0;
    q->tail = -1;
    q->count = 0;
}
void enqueue(queue *q, queue_item x)
{
    if (!queue_full(*q))
    {
        q->tail = (q->tail + 1) % QUEUE_MAX_SIZE;
        q->items[q->tail] = x;
        q->count++;
    }
}
queue_item dequeue(queue *q)
{
    if (!queue_empty(*q))
    {
        queue_item x = q->items[q->head];
        q->head = (q->head + 1) % QUEUE_MAX_SIZE;
        q->count--;
        return x;
    }
}


queue_item queue_top(queue q)
{
    return q.items[q.head];
}

int queue_full(queue q)
{
    return (q.count == QUEUE_MAX_SIZE);
}

int queue_empty(queue q)
{
    return (q.count == 0);
}