loop_cnt_sh.vhd

Go to the documentation of this file.

--**************************************************************
--*                                                            *
--*     The source code for the ATLAS BCM "AAA" FPGA is made   *
--*     available via the GNU General Public License (GPL)     *
--*     unless otherwise stated below.                         *
--*                                                            *
--*     In case of problems/questions/bug reports etc. please  *
--*     contact michael.niegl@cern.ch                          *
--*                                                            *
--**************************************************************

--**************************************************************
--*                                                            *
--*  $Source: /local/reps/bcmfpga/bcm_aaa/bcm_aaa/div/loop_cnt_sh.vhd,v $
--*  $Revision: 1.3.2.3 $                                         *
--*  $Name: dev $                                                 *
--*  $Author: mniegl $                                         *
--*  $Date: 2008/11/03 17:57:45 $                              *


--*                                                            *
--**************************************************************


library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_arith.all;

use ieee.std_logic_unsigned.all;

use ieee.numeric_std.all;


entity loop_cnt_sh is
  port (
    CLK   : in  std_logic;
    EN    : in  std_logic;
    RESET : in  std_logic;
    Y     : out std_logic_vector(5 downto 0)
    );

end loop_cnt_sh;


architecture loop_cnt_sh_arc of loop_cnt_sh is

  signal cnt_i : std_logic_vector(5 downto 0) := (others => '0');
  signal up    : std_logic                    := '0';
  
begin  -- loop_cnt_arc

  Y <= cnt_i;

  counter : process(CLK)
  begin
    if CLK'event and CLK = '1' then
      if RESET = '1' then
        cnt_i <= (others => '0');
        up    <= '1';
      else
        if EN = '1' then
          
          if up = '1' then
            if cnt_i = "111111" then
              up    <= '0';
              cnt_i <= cnt_i - 1;
            else
              cnt_i <= cnt_i + 1;
            end if;
            
          else
            if cnt_i = "000000" then
              up    <= '1';
              cnt_i <= cnt_i + 1;
            else
              cnt_i <= cnt_i - 1;
            end if;
          end if;
          
        else
          cnt_i <= cnt_i;
        end if;
      end if;
    end if;
  end process counter;

end loop_cnt_sh_arc;

---

Author: M.Niegl

Generated on Tue Nov 4 00:47:04 2008 for BCM-AAA by  1.5.7.1-20081012