ENTITY rowend_x0 IS GENERIC ( CONSTANT area : NATURAL := 250; CONSTANT transistors : NATURAL := 0 ); PORT ( vdd : in BIT; vss : in BIT ); END rowend_x0; ARCHITECTURE behaviour_data_flow OF rowend_x0 IS BEGIN ASSERT (vdd and not (vss)) REPORT "power supply is missing on rowend_x0" SEVERITY WARNING; END;