architecture DATAFLOW of CONVERTER is
begin
  E(3) <= B(3) or (B(2) and B(1))  or (B(2) and B(0));
  E(2) <= (B(3) and B(2)) or (not B(2) and B(1)) or (not B(2) and B(0))
          or (B(2) and not B(1) and not B(0));
  E(1) <= (not B(1) and not B(0)) or (B(1) and B(0)) or (B(3) and B(1))
          or (B(2) and B(3));
  E(0) <= not B(0) or (B(3) and B(1)) or (B(3) and B(2));
end DATAFLOW;