Computer Engineering 465 / Electrical Engineering 543
DIGITAL VLSI
SYSTEMS
Low
Level Component File
This file contains the VHDL lower
level component code of the "subtraction" circuit.
LIBRARY ieee; -- Include the ieee library
USE ieee.std_logic_1164.ALL; -- Logical naming of the 1164 part
PACKAGE sub_pkg IS -- Package declaration for "subtract"
COMPONENT subtract IS -- Include subtract circuit
PORT(a,b: IN std_logic; -- Port list
c: OUT std_logic);
END COMPONENT subtract;
END PACKAGE sub_pkg;
LIBRARY ieee; -- Include the ieee library
USE ieee.std_logic_1164.ALL; -- Logical naming of the 1164
ENTITY subtract IS -- Entity declaration for "subtract" circuit
PORT(a,b : IN std_logic; -- Port list
c: OUT std_logic);
END ENTITY subtract;
ARCHITECTURE subtract_arch OF subtract IS -- Architecture for subtract
BEGIN
proc_1: PROCESS(a, b) IS -- Define one process sensitive to a & b
BEGIN
c <= a xor b; -- Normal bit subtraction
END PROCESS proc_1;
END ARCHITECTURE subtract_arch;
