#include "palindromatic.h"
static void pm_queue_init(queue_t *queue)
{
queue->front = queue->rear = -1;
for(int i = 0; i<QUEUE_SZ; i++) queue->reqs[i] = NULL;
}
static long pm_queue_enqueue(queue_t *queue, request_t *req)
{
if((queue->front == 0 && queue->rear == QUEUE_SZ-1) || (queue->rear+1)%QUEUE_SZ == queue->front) return -1;
else if(queue->front == -1)
{
queue->front = queue->rear = 0;
queue->reqs[queue->rear] = req;
}
else if(queue->rear == QUEUE_SZ-1 && queue->front != 0)
{
queue->rear = 0;
queue->reqs[queue->rear] = req;
}
else
{
queue->rear++;
queue->reqs[queue->rear] = req;
}
return queue->rear;
}
static request_t *pm_queue_dequeue(queue_t *queue)
{
if(queue->front == -1) return NULL;
request_t *req = queue->reqs[queue->front];
queue->reqs[queue->front] = NULL;
if(queue->front == queue->rear) queue->front = queue->rear = -1;
else if(queue->front == QUEUE_SZ-1) queue->front = 0;
else queue->front++;
return req;
}
static request_t *pm_queue_peek(queue_t *queue)
{
if(queue->front == -1) return NULL;
else return queue->reqs[queue->front];
}
static int pm_queue_count(queue_t *queue)
{
if(queue->front == -1)
return 0;
else if(queue->rear >= queue->front)
return queue->rear-queue->front+1;
else
return QUEUE_SZ - queue->front + queue->rear + 1;
}