Signal parameter in a subprogram is not supported error - vhdl

Question

My code is about a ping pang game using VHDL and maxplus2. I can't get it complied.
library ieee;
use ieee.std_logic_1164.all;
-- use ieee.std_logic_unsigned.all;
-- use ieee.std_logic_arith.all;
entity center is
port (
clk: in std_logic;
ca: in std_logic;
cb: in std_logic;
enable: in std_logic;
a: in std_logic;
b: in std_logic;
ball: out std_logic_vector(16 downto 0);
sa: out std_ulogic;
sb: out std_ulogic;
over: inout std_ulogic
);
end center;
architecture behavior of center is
signal direction : integer range 0 to 2;
signal num : integer range -1 to 17;
begin
process (enable,ca,cb,a,b,clk)
begin
if enable = '0' then
over <= '0';
sa <= '0';
sb <= '0';
elsif enable = '1' and rising_edge(clk) then
if direction = 2 then
if ca = '1' then
direction <= 0;
num <= 1;
elsif cb = '1' then
direction <= 1;
num <= 16;
else
direction <= 2;
num <= 8;
end if;
elsif direction = 0 and num > 0 then
if b = '1' then
if num < 2 then
num <= num - 1;
direction <= 1;
else
direction <= 2;
sa <= '1' after 10 ns;
sb <= '0' after 10 ns;
over <= not over after 10 ns;
end if;
end if;
elsif direction = 1 and num <= 16 then
if a = '1' then
if num >= 14 then
num <= num + 1;
direction <= 2;
else
direction <= 2;
sa <= '0' after 10 ns;
sb <= '1' after 10 ns;
over <= not over after 10 ns;
end if;
end if;
elsif direction = 0 and num = -1 then
num <= 8;
direction <= 2;
sa <= '0' after 10 ns;
sb <= '1' after 10 ns;
over <= not over after 10 ns;
elsif direction = 0 and num = -1 then
num <= 8;
direction <= 2;
sa <= '0' after 10 ns;
sb <= '1' after 10 ns;
over <= not over after 10 ns;
end if;
end if;
end process;
end architecture behavior;
But I get a error:
signal parameter in a subprogram is not supported
I am confused, I don't know why I get this error.

Answer 1

I think as David also said you need to provide more information.
What it looks like for me is that your are writing a test bench the above code cannot be synthesized correctly. ISE will tell you that your syntax is ok but the delays are ignored IE the after keyword. The after keyword is only used in simulation.
That said i would also clean up the code there are a lot of redundancies. FX
The last two elsif statements. only one is needed. and the sensitivity list. only clk and enable should be there.
I've tried to clean up your code:
process (enable,clk)
begin
if enable = '0' then
over <= '0';
sa <= '0';
sb <= '0';
elsif rising_edge(clk) then
case( direction ) is
when 0 =>
if num > 0 then
if b = '1' then
if num < 2 then
num <= num - 1;
direction <= 1;
else
direction <= 2;
sa <= '1' after 10 ns;
sb <= '0' after 10 ns;
over <= not over after 10 ns;
end if;
end if;
elsif num = -1 then
num <= 8;
direction <= 2;
sa <= '0' after 10 ns;
sb <= '1' after 10 ns;
over <= not over after 10 ns;
end if;
when 1 =>
if num <= 16 then
if a = '1' then
if num >= 14 then
num <= num + 1;
direction <= 2;
else
direction <= 2;
sa <= '0' after 10 ns;
sb <= '1' after 10 ns;
over <= not over after 10 ns;
end if;
end if;
end if;
when 2 =>
if ca = '1' then
direction <= 0;
num <= 1;
elsif cb = '1' then
direction <= 1;
num <= 16;
else
direction <= 2;
num <= 8;
end if;
when others => NULL;
end case ;
end if;
end process;
Try and remove your after keywords and see if it will compile then.