A testing queue.

gistfile1.c

/* A code for queue. */
#include <stdio.h>
#include <stdlib.h>
#define MAX_SIZE	5
#define DELTA_SIZE	5

typedef struct _queue
{
	int size;
	int *data;
	int head, tail;
}queue, *p_queue;

void
init(p_queue q)
{
	q->size = MAX_SIZE+1;
	q->head = q->tail = 0;
	q->data = (int *)malloc(q->size * sizeof(int));
}

void
clear(p_queue q)
{
	q->head = q->tail = 0;
}

void
destory(p_queue q)
{
	free(q->data);
}

int
is_empty(queue q)
{
	if( q.head == q.tail )
		return 1;
	return 0;
}

int
is_full(queue q)
{
	if( (q.tail+1)%(q.size) == q.head )
		return 1;
	return 0;
}

void
greaten(p_queue q)
{
	int i = 0;
	int tsize = q->size + DELTA_SIZE;
	int *tmd = (int *)malloc(tsize * sizeof(int));
	
	/* copying. */
	for(i = q->head;(i)%(q->size) != q->tail;++i)
		*(tmd+i-q->head) = *(q->data+(i)%(q->size));
	q->tail = i-q->head;
	q->head = 0;
	free(q->data);
	q->data = tmd;
	q->size = tsize;
}

void
enqueue(p_queue q, int e)
{
	if( is_full(*q) )
		greaten(q);
	q->data[q->tail] = e;
	q->tail = (q->tail+1)%(q->size);
}

int
dequeue(p_queue q, int *x)
{
	if( is_empty(*q) )
		return 0;
	*x = q->data[q->head];
	q->head = (q->head+1)%(q->size);
	return 1;
}

void
print(queue q)
{
	int i = 0;
	for(i = 0;i < q.size;++i)
		printf("%s%s%d ", (i==q.head)?("*"):(""), i==q.tail?("$"):(""), q.data[i]);
	printf("\n");
}

int main(void)
{
	queue q;
	return ;
}