/* This class defines a simulator for page replacement algorithms.

 * You can use any page replacement algorithm.

 * Any method of generating page references can be used. 

 */

public class Simulator {

    /* This class defines the history of page accesses. 

     * The pageString gives the page numbers in the order of reference.

     * The faultStgring tells whether a page fault was encountered for this reference. 

     * The numPageFaults gives the total number of page faults.

     * The numReferences gives the number of references in the pageString.

     */

    public class History {

	public int numPageFaults;

	public int numReferences;

	public int pageString[];

	public boolean faultString[];



	public History (int numReferences) {

	    pageString = new int[numReferences];

	    faultString = new boolean[numReferences];



	    for (int i=0; i<numReferences; i++) {

		pageString[i] = -1;

		faultString[i] = false;

	    }

	    numPageFaults++;

	}

	

	public void print() {

	    for (int i=0; i<pageString.length; i++) {

		System.out.println(pageString[i]+" "+faultString[i]);

	    }

	}

    }



    private int numReferences;  /* number of references to be generated. */

    private PageManager pageManager;  /* user defined page manager. */

    private ReferenceGenerator referenceGenerator; /* user defined reference generator. */

    private MemoryInterface memoryInterface; /* simulates main memory. */



    /* This constructor initializes the simultor. 

     */

    public Simulator (int numReferences, PageManager pageManager, ReferenceGenerator referenceGenerator, MemoryInterface  memoryInterface) {

	this.numReferences = numReferences;

	this.pageManager = pageManager;

	this.referenceGenerator = referenceGenerator;

	this.memoryInterface = memoryInterface;

    }



    /* This method runs the simutation.

     * The reference genrator is initialized seed 0.

     * It returns the history of the simulation.

     */

    public History simulate () {

	return simulate(0);

    }



    /* This method runs the simutation.

     * The reference generator is initialized with the given seed.

     * It returns the history of the simulation.

     */

    public History simulate (long seed) {

	History history = new History(numReferences);



	memoryInterface.reset();

	referenceGenerator.init(seed);



	for (int i=0; i<numReferences; i++) {

	    int page = referenceGenerator.nextReference();

	    

	    history.pageString[i] = page;

	    if (!memoryInterface.isMapped(page)) {

		pageManager.handlePageFault(page,memoryInterface);

		history.faultString[i] = true;

	    }

	    pageManager.handlePageReference(page, memoryInterface);

	}

	return history;

    }

}