The role of structural VHDL is to describe circuits in terms of
sub-components and interconnections. In this figure the simple logic
elements are used to design a full adder. A structural description
looks at the hardware as a netlist or schematic of the device; the
components and interconnects are seen, but the internal function is
hidden.
A structural description can tie together components of any
complexity. A gate level description or the subunits of a
microprocessor can be connected just as readily.
