import java.awt.*;

/***********************************************************************
 *	File:     ExtendedALU.java
 *    Aurthor:  Dr. Dalton R. Hunkins
 *              Computer Science Department
 *              St. Bonaventure University
 *    Date:     November 2008
 *
 *    Purpose:
 *       The file is a stub that allows the reader/programmer to extend
 *       the ALU within the Data Path Simulator, PathSim, to handle
 *       additional MIPS operators. The extension is accomplished
 *       through adding java code to the method execute. See the lab
 *       instruction comment given below.
 *
 *   Class Modified by:
 ***********************************************************************/   

class ExtendedALU extends ALU {
	private DataLine aluControl, input1, input2, result, zero; 
	private DataPath parent;
/***********************************************************************
   The Data Lines are
	aluControl - the line coming from the ALU Control unit
	input1     - the line coming from the Registers
	input2     - the line coming from the Mux
	result     - the output line going from the ALU to Data Memory
	zero	     - the output line going to the And gate and carries
		       either "0" or "1"

***********************************************************************/
	
	public ExtendedALU(double x[], double y[], int n, 
			Color color, String label, String name,
	        DataLine aluControl, DataLine input1, DataLine input2, 
	        DataLine result, DataLine zero, DataPath parent) {
	   super(x, y, n, color, label, name, aluControl, input1, input2,
               result, zero);

	   this.input1     = input1;
	   this.input2     = input2;
	   this.aluControl = aluControl;
	   this.result     = result;
	   this.zero       = zero;
	   this.parent     = parent;
	}
	
	public void execute() {
	   int operation     = (int) hexStringToUnsigned(aluControl.getValue());
	   int signedNumber1 = hexStringToSigned(input1.getValue());
	   int signedNumber2 = hexStringToSigned(input2.getValue());

/*********************************************************************
               INSTRUCTIONS FOR LAB C
   Currently, the method is implemented by the call super.execute()
   as seen with the code written below. However, the parent super
   does nothing with the extensions. Therefore, you must write your 
   code here for those extensions. In particular, super handles 
   the aluControl values 0, 1, 2, 6 and 7. 
   
   For this lab, you must write code to handle the following 
   aluControl input value (stored in operation) by placing 
   appropriate values on the output lines this.result and 
   this.zero
         aluControl = A -> bne
   (Note: nothing more needs to be done here
     for the MIPS operators addi, andi, ori and xori. WHY?)

    To accomplish your task, you will need to do the appropriate
    computations and make the appropriate decision for bne as to
    the values you place on the output lines. For either of these
    lines, you make a call to the following method

    public void setValue(String value) 
	precondition: 
	   value is any String
	postcondition:
	   value is put on the data line and appears with
	   a mouse click on the line
 
    The value you place on the line this.result must be a String
    of eight hex digits. You may want to use the following method 
    in this case.
    
    protected String signedToHexString(int number, 
                                       int numberOfDigits)
	precondition:
	   number is any 32 bit integer
         numberOfDigits is any positive integer
	postcondition:
	   a String of numberOfDigits (e.g. 8 digit) is returned. The
         string is a sequence of hex digits that is equivalent to
         the 32 bit integer 
 
    In the case of the output line this.zero, you will be making
    either of the following calls
         this.zero.setValue("0");
    or
         this.zero.setValue("1");
    Keep in the note on "hacking" the appropriate that was given in
    the lab writeup.
**********************************************************************/
       super.execute();
    }	
}