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-- $Id: gray2bin_gen.vhd 418 2011-10-23 20:11:40Z mueller $
--
-- Copyright 2007- by Walter F.J. Mueller <W.F.J.Mueller@gsi.de>
--
-- This program is free software; you may redistribute and/or modify it under
-- the terms of the GNU General Public License as published by the Free
-- Software Foundation, either version 2, or at your option any later version.
--
-- This program is distributed in the hope that it will be useful, but
-- WITHOUT ANY WARRANTY, without even the implied warranty of MERCHANTABILITY
-- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
-- for complete details.
-- 
------------------------------------------------------------------------------
-- Module Name:    gray2bin_gen - syn
-- Description:    Gray code to binary converter
--
-- Dependencies:   -
-- Test bench:     tb/tb_debounce_gen
-- Target Devices: generic
-- Tool versions:  xst 8.1, 8.2, 9.1, 9.2; ghdl 0.18-0.25
-- Revision History: 
-- Date         Rev Version    Comment
-- 2007-12-26   106   1.0      Initial version 
------------------------------------------------------------------------------
 
library ieee;
use ieee.std_logic_1164.all;
 
use work.slvtypes.all;
 
entity gray2bin_gen is                  -- gray->bin converter, generic vector
  generic (
    DWIDTH : positive := 4);            -- data width
  port (
    DI : in slv(DWIDTH-1 downto 0);     -- gray code input
    DO : out slv(DWIDTH-1 downto 0)     -- binary code output
  );
end entity gray2bin_gen;
 
 
architecture syn of gray2bin_gen is
 
begin
 
  proc_comb: process (DI)
 
    variable ido : slv(DWIDTH-1 downto 0);
 
  begin
 
    ido := (others=>'0');
 
    ido(DWIDTH-1) := DI(DWIDTH-1);
    for i in DWIDTH-2 downto 0 loop
      ido(i) := ido(i+1) xor DI(i);
    end loop;
 
    DO <= ido;
 
  end process proc_comb;
 
end syn;