Procedures (cont. 1)

ARCHITECTURE behavior OF adder IS
BEGIN
    PROCESS (enable, x, y)
    BEGIN
    add_bits3(x, y, enable, result, carry);
    END PROCESS;
END behavior;
With parameter passing, it is possible to further simplify the architecture
The parameters must be compatible in terms of data flow and data type
PROCEDURE add_bits3

(SIGNAL a, b, en : IN BIT;
 SIGNAL temp_result,
temp_carry : OUT BIT)