package_ohms.vhd

老师给我们的vhdl源代码

LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
PACKAGE  my_package  IS 
CONSTANT LENGTH: INTEGER := 8;   
TYPE  cyweek  IS  ( sunday, monday, tuesday, wednesday, thursday, friday, saturday ) ;
SUBTYPE  reverse_cyweek  IS  cyweek   RANGE saturday  DOWNTO  sunday ;     
TYPE  voltage  IS  RANGE  0 TO 1000000   
UNITS
	uV ;  
	mV = 1000 uV ;  
	V = 1000 mV ;   
END  UNITS ;
TYPE  current  IS  RANGE  0 TO 1000000  
UNITS
	uA ;  
	mA = 1000 uA ;   
	A = 1000 mA ;    
END  UNITS ;
TYPE  resistance  IS  RANGE  0 TO 1000000 
UNITS
	ohm ; 
	kohm = 1000 ohm ;
	mohm = 1000 kohm ;
END  UNITS ;
FUNCTION "+"(L: INTEGER; R: BIT)
		RETURN INTEGER;
END  my_package ;
PACKAGE BODY my_package IS
    FUNCTION "+"(L: INTEGER; R: BIT)		RETURN INTEGER IS
        BEGIN
        IF (R='1') THEN
        RETURN L+1;
        ELSE
        RETURN L;
        END IF;
     END;
        END PACKAGE BODY;