Keyword: NULL

Null is a statement that performs no action.

The null statement can be used in situations where it is necessary to explicitly specify that no action is needed.  For example, a null statement may be useful in a case statement where all alternatives must be specified but where no action may be required for some alternatives.

Example

    D1 <= ‘0’;  -- Default values...

    Strobe <= ‘0’;

    Rdy <= ‘0’;

    case current_state is

      when S0 =>

        D1 <= ‘1’;

      when S1 =>

        Strobe <= ‘1’;

      when S2 =>

        Rdy <= ‘1’;

      when others =>

        null;

    end case;

LRM

    8.13

See also

  Case statement