control.cpp

#include "control.h"

/**
 * \c control module callback function.
 */
void control::entry()
{
  jbr.write(0);
  switch(opcode.read()) {
    
    case 0: // R-format
        
        RegDst.write(1);  
        ALUSrc.write(0);
	    MemtoReg.write(0);
	    RegWrite.write(1);
	    MemRead.write(0);
	    MemWrite.write(0);

	    switch(funct.read()) {
	       case 8: jbr.write(6);  // jr
	       	       break;

	       case 32: ALUOp.write(2); // add
	                break;
	       case 34: ALUOp.write(6); // subtract
	                break;
	       case 36: ALUOp.write(0); // bitwise AND
	                break;
	       case 37: ALUOp.write(1); // Bitwise OR
	                break;
	       case 42: ALUOp.write(7); // Set to 1 if Less Than
	                break;
		}
	    break;

    case  2: // j
        ALUSrc.write(0);
	    RegWrite.write(0);
	    MemRead.write(0);
	    MemWrite.write(0);
	    ALUOp.write(6);

	    jbr.write(5);
	    
	    break;

    case  4: // beq
        ALUSrc.write(0);
	    RegWrite.write(0);
	    MemRead.write(0);
	    MemWrite.write(0);
	    ALUOp.write(6);

	    jbr.write(1);
	    
	    break;

    case  5: // bne
        ALUSrc.write(0);
	    RegWrite.write(0);
	    MemRead.write(0);
	    MemWrite.write(0);
	    ALUOp.write(6);

	    jbr.write(2);
	    
	    break;
	    
    case  6: // blez
        ALUSrc.write(0);
	    RegWrite.write(0);
	    MemRead.write(0);
	    MemWrite.write(0);
	    ALUOp.write(6);

	    jbr.write(4);
	    
	    break;

    case  7: // bgtz
        ALUSrc.write(0);
	    RegWrite.write(0);
	    MemRead.write(0);
	    MemWrite.write(0);
	    ALUOp.write(6);

	    jbr.write(3);
	    
	    break;

    case 35: // lw
        RegDst.write(0); 
        ALUSrc.write(1);
	    MemtoReg.write(1);
	    RegWrite.write(1);
	    MemRead.write(1);
	    MemWrite.write(0);
	    ALUOp.write(2);
	    
	    jbr.write(0);
	    
	    break;
    case 43: // sw
        ALUSrc.write(1);
	    RegWrite.write(0);
	    MemRead.write(0);
	    MemWrite.write(1);
	    ALUOp.write(2);
	    
	    jbr.write(0);
	    
	    break;
   default: // Unknown opcode
            fprintf(stderr,"ERROR: Illegal opcode\n");
	    //assert(0);
	    break;
    }
}