The following example uses a procedure within a package:
Filename: procedure_package_1.vhd
-- Declaration of a procedure in a package
--
-- Download: procedure_package_1.vhd
--
package PKG is
procedure ADD(
A, B, CIN : in BIT;
C : out BIT_VECTOR(1 downto 0));
end PKG;
package body PKG is
procedure ADD(
A, B, CIN : in BIT;
C : out BIT_VECTOR(1 downto 0)) is
variable S, COUT : BIT;
begin
S := A xor B xor CIN;
COUT := (A and B) or (A and CIN) or (B and CIN);
C := COUT & S;
end ADD;
end PKG;
use work.PKG.all;
entity procedure_package_1 is
port(
A, B : in BIT_VECTOR(3 downto 0);
CIN : in BIT;
S : out BIT_VECTOR(3 downto 0);
COUT : out BIT
);
end procedure_package_1;
architecture ARCHI of procedure_package_1 is
begin
process(A, B, CIN)
variable S0, S1, S2, S3 : BIT_VECTOR(1 downto 0);
begin
ADD(A(0), B(0), CIN, S0);
ADD(A(1), B(1), S0(1), S1);
ADD(A(2), B(2), S1(1), S2);
ADD(A(3), B(3), S2(1), S3);
S <= S3(0) & S2(0) & S1(0) & S0(0);
COUT <= S3(1);
end process;
end ARCHI;