#include <stdio.h>
#include <stdlib.h>

#include "queue.h"


queue* qu_create( )
{
    queue* sq;

    sq = malloc(sizeof(*sq));
    if (NULL == sq)
        return NULL;

    sq->head = 0;
    sq->tail = 0;

    return sq;
}

int qu_isempty(queue* sq)
{
    return (sq->head == sq->tail);
}

int qu_enqueue(queue* sq, datatype* x)
{
    if ((sq->tail + 1) % MAXSIZE == sq->head)
        return -1;

    sq->tail           = (sq->tail + 1) % MAXSIZE;
    sq->data[sq->tail] = *x;

    return 0;
}

int qu_dequeue(queue* sq, datatype* x)
{
    if (qu_isempty(sq))
        return -1;

    sq->head = (sq->head + 1) % MAXSIZE;
    *x       = sq->data[sq->head];

    return 0;
}

void qu_travel(queue* sq)
{
    if (sq->head == sq->tail)
        return;

    int i;

    i = (sq->head + 1) % MAXSIZE;
    while (i != sq->tail)
    {
        printf("%d ", sq->data[i]);
        i = (i + 1) % MAXSIZE;
    }
    printf("%d \n", sq->data[i]);
}

void qu_clear(queue* sq)
{
    sq->head = sq->tail;
}

void qu_destroy(queue* sq)
{
    free(sq);
}