import java.awt.*;

/***********************************************************************
 *	File:     ExtendedALU.java
 *    Aurthor:  Dr. Dalton R. Hunkins
 *              Computer Science Department
 *              St. Bonaventure University
 *    Date:     17 January 2006
 *
 *    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 LABS B and 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. 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
    And for lab C, your code must 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 for lab B and/or lab C, 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).  
    You will also need to place values on the output lines
    this.result and this.zero using the method setValue belonging
    to the DataLine class and the inherited utility method 
    signedToHexString described as follows:

    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

    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 development/debugging purposes, you may also wish to use the
    the following method:

    parent.displayMessage(String message)
       precondition:
          message is any string
       postcondition:
          the message is displayed in an alert box
**********************************************************************/
       super.execute();
    }	
}