public void executeSLL(RTypeInstruction instruction) { 
		RegisterFile regFile = RegisterFile.getInstance();
		int value = regFile.getRegisterValue(instruction.getRegSource2()) 
				<< instruction.getShift() ;
		regFile.setRegisterValue(regFile.getRegisterValue(instruction.getRegTarget()), value);
		AppContext.PROGRAM_COUNTER++;	
		/* -- Shift left logical

	Description:
	Shifts a register value left by the shift amount listed in the instruction and places the result in a third register. Zeroes are shifted in.
	Operation:
	$d = $t << h; advance_pc (4);
	Syntax:
	sll $d, $t, h
	Encoding:
	0000 00ss ssst tttt dddd dhhh hh00 0000
		 */ 
	}