esTc 设计中 Component Declaration and Instantiation Next-level of hierarchy design must have a Component Declaration for a lower-level design before it can be Instantiated ARCHITETURE structure view OF Full adder Is CoMPONENT half adder PORT(a, b: IN BIT; S, C: OUT BIT) END COMPONENT SIGNAL a b c BIT BEGIN u1: half adder PORT MAP(X,y, a, b) END structure_view设计中心 Component Declaration and Instantiation • Next-level of hierarchy design must have a Component Declaration for a lower-level design before it can be Instantiated ARCHITETURE structure_view OF Full_adder IS COMPONENT half_adder PORT (a, b : IN BIT ;s ,c : OUT BIT); END COMPONENT; SIGNAL a,b,c:BIT; BEGIN u1: half_adder PORT MAP (x,y,a,b); …… END structure_view;