/***********************************************************************************
  Engineering 3891 Advanced Structured Programming
  Assignment: 4  Date Due: October 12th/2000
  Name: Daryl Martin
  Student #: 9713520
  Username: darylm
 ***********************************************************************************/
#include "assign4.h"

namespace std
{
  int queue[QSIZE];		//This will declare the size of the Queue from assign4.h
  
  int *tail = queue;	//Next open postion in the queue
  
  int *head = queue;	//The head queue item
  
  status currentStatus = EMPTY;  //The current status of the Queue
}
using namespace std;

/***********************************************************************************
 * getStatus -- Returnns the current status of teh queue
 *
 * Parameters: 
 *			None
 *
 * Modifies: none
 *
 * Returns: The current status of the queue		Date:  10/12/00
 ***********************************************************************************/

status getStatus (void)
{
  return currentStatus;
}

/***********************************************************************************
 * putQueue -- Takes a number and places it into the queue at the tail if 
 *			   their is room
 *
 * Parameters: 
 *		item -- the intereger to put into the queue
 *
 * Modifies: none
 *
 * Returns: The current status of the queue		Date:  10/12/00
 ***********************************************************************************/

status putQueue (int item)
{

	if (currentStatus == FULL)
      currentStatus = OVERFLOW; //Overflow status
	  
	if (currentStatus != OVERFLOW)	//!= OVERFLOW shows us that their is room left
    {				
      *tail = item;
      tail++;
      currentStatus = PENDING;
	
	if ((tail - queue) == QSIZE)
		tail = queue;			//If it went to the end go back	
								
	if (tail == head)			
	  currentStatus = FULL;	//Move to the Head....
    }

  return currentStatus;
}

 /***********************************************************************************
 * getQueue -- This will return the value at the first element. 
 *			   If none then a zero will be returned.
 *
 * Parameters: 
 *			None
 *
 * Modifies: none
 *
 * Returns: The first value of the queue. A zero if non exist		Date:  10/12/00
 ***********************************************************************************/

int
getQueue (void)
{
	int zeroTerm = 0;	//In case the queue is zero		

	if (currentStatus == EMPTY)
		currentStatus = UNDERFLOW;  //Nothign in the head.  Hence the Underflow

	if (currentStatus != UNDERFLOW)		//If the elemet's exist at *head
    {				
		zeroTerm = *head;
		head++;

		if (head == (queue + QSIZE))
		head = queue;		//if you pass the end of the queue reset it

		if (tail == head)
		currentStatus = EMPTY;
	
		else
		currentStatus = PENDING;
    }
  return zeroTerm;
}