counter_up_down.vhd

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-- turn off superfluous VHDL processor warnings 
-- altera message_level Level1 
-- altera message_off 10034 10035 10036 10037 10230 10240 10030 

library altera;
use altera.altera_europa_support_lib.all;

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_arith.all;
use ieee.std_logic_unsigned.all;

entity counter_up_down is 
        port (
              -- inputs:
                 signal address : IN STD_LOGIC_VECTOR (1 DOWNTO 0);
                 signal clk : IN STD_LOGIC;
                 signal in_port : IN STD_LOGIC;
                 signal reset_n : IN STD_LOGIC;

              -- outputs:
                 signal readdata : OUT STD_LOGIC
              );
end entity counter_up_down;


architecture europa of counter_up_down is
                signal clk_en :  STD_LOGIC;
                signal data_in :  STD_LOGIC;
                signal read_mux_out :  STD_LOGIC;

begin

  clk_en <= std_logic'('1');
  --s1, which is an e_avalon_slave
  read_mux_out <= to_std_logic((((std_logic_vector'("000000000000000000000000000000") & (address)) = std_logic_vector'("00000000000000000000000000000000")))) AND data_in;
  process (clk, reset_n)
  begin
    if reset_n = '0' then
      readdata <= std_logic'('0');
    elsif clk'event and clk = '1' then
      if std_logic'(clk_en) = '1' then 
        readdata <= read_mux_out;
      end if;
    end if;

  end process;

  data_in <= in_port;

end europa;