public int decodeInstruction(int instruction) {

		    switch (instruction & 0b11110000) {
		      case 0b00000000: return 0;
		      case 0b00010000: return 16;
		      case 0b00100000: return 32;
		      case 0b00110000: return 48;
		      case 0b01000000: return 64;
		      case 0b01010000: return 80;
		      case 0b01100000: return 96;
		      case 0b01110000: return 112;
		      default: throw new IllegalArgumentException();
		    }
		  
		}