Package body

package body package _simple_name is
     package_body_declarative_part
end [ package body ]
        [ package _simple_name ] ;

• identifier

{ package_body_declarative_item }

The objects from the library pck_0 are integrated. In the package body the constant cint , which has to be declared in the package header, is declared as integer and initialized with the result value from function call f(6) (deferred constant).

 USE work.pck_0.all;
PACKAGE BODY pck IS
   CONSTANT cint : integer := f(6);
END pck ;

Definition of the package body pck_1 in which the two functions G and F are declared.

In the function G the value of the equation A XOR B is returned as a result (as Bit).

In the function F a variable V is declared as Bit which then receives the value from S1 NAND S2 . The function F delivers the bit-value from the function call G(V, S2) as a result value.

PACKAGE BODY pck_1 IS
 
   FUNCTION G ( A, B : Bit )
      RETURN Bit IS
   BEGIN
      RETURN NOT ( A XOR B );
   END ;
 
   FUNCTION F ( S1, S2 : Bit )
      RETURN Bit IS
   VARIABLE V : Bit;
   BEGIN
      V := S1 NAND S2;
      RETURN G(V, S2);
   END ;
 
END pck_1 ;

Definition of the package body tristate in which the two functions BitVal and TriVal are declared.

In the function BitVal a constant Bits is declared and initialized with the value “0100”. As a result, the value of the bit in the position Tri'Pos ( Value ) of Bits is returned.

In the function TriVal a variable V of the type Tri is declared and initialized with the value Z .

In LOOP either the value of Source(i) is transferred to V or E is returned as a result value, depending on the individual value of Source(i) and V . In the first case V is returned as a result value afterwards.

PACKAGE BODY tristate IS
 
   FUNCTION BitVal ( Value : Tri )
      RETURN Bit IS
   CONSTANT Bits : Bit_Vector := "0100";
   BEGIN
      RETURN Bits(Tri'Pos(Value))
   END ;
 
   FUNCTION TriVal ( Value : Bit )
         RETURN Tri IS
   VARIABLE V : Tri := 'Z';
   BEGIN
      FOR i IN Sources'Range LOOP
         IF Sources(i) /= 'Z' THEN
            IF V = 'Z' THEN
               V := Sources(i);
            ELSE
               RETURN 'E';
            END IF ;
         END IF ;
      END LOOP ;
   RETURN V ;
   END ;
 
END tristate ;