case SSalt is
            when "00" => tmp <= "00";
            when "01" => if CSalt = '0' and Z = '0' then tmp <= "00";
                         elsif CSalt = '0' and Z = '1' then tmp <= "01";
                         elsif CSalt = '1' and Z = '0' then tmp <= "01";
                         elsif CSalt = '1' and Z = '1' then tmp <= "00";
                         end if;
            when "10" => tmp <= "10";
            when "11" => if Csalt = '0' then tmp <= "01";
                         else tmp <= "11";
                         end if;
        end case;