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 B
   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. Now for Lab B, your
   code must handle any of the following aluControl input values 
   (stored in operation) by placing appropriate values on the 
   output lines this.result and this.zero
         aluControl = 3 -> nor
         aluControl = 4 -> xor
         aluControl = 5 -> sllv
         aluControl = 8 -> srav
         aluControl = 9 -> srlv
    To accomplish your task, you will need to do the appropriate
    computations for the operations (this is a simulator and we CAN 
    write the operations in Java versus constructing circuits). The
    result of the operation will then be placed on the line with
    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
 
    Observe that setValue requires a String and that string is the
    hexadecimal representation of the computed result and is given as
    eight hex digits. You can use the following available method to 
    handle the necessary conversion.
    
    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 

    For example, if you store the computed integer result in the local   
    variable computedResult, you then make the call

        this.result.setValue(computedResult, 9);
 
    For setting the value on the zero line, we simply make either the
    call
            this.zero("0");
    or the call
            this.zero("1");
**********************************************************************/
       super.execute();
    }	
}