包集合的简单定义 library ieee; use ieee std logic 1164. all; packge upac is constant k: integer: 4 subtype cpu bus is std logic vector(k-Idownto 0); end upac包集合的简单定义 library ieee; use ieee.std_logic_1164.all; packge upac is constant k: integer := 4; subtype cpu_bus is std_logic_vector(k-1downto 0); end upac;