Subversion Repositories spi_slave

-------------------------------------------------------------------------------

--* 

--* @short convert binary input vector to gray

--* 

--* @generic width              with of input vector

--*

--*    @author: Daniel Köthe

--*   @version: 1.0

--* @date:      2007-11-11

--/

-------------------------------------------------------------------------------

library ieee;

use ieee.std_logic_1164.all;

use ieee.std_logic_unsigned.all;

use ieee.std_logic_arith.all;

entity bin2gray is

  generic (

    width : integer := 4);

  port (

    in_bin   : in  std_logic_vector(width-1 downto 0);

    out_gray : out std_logic_vector(width-1 downto 0));

end bin2gray;

architecture behavior of bin2gray is

begin  -- behavior

  -- Sequence: 0,1,3,2,6,7,5,4,C,D,F,E,A,B,9,8

  --* convert binary input vector to gray

  bin2gray_proc : process(in_bin)

  begin

    out_gray(width-1) <= in_bin(width-1);

    -- out_gray(3) <= in_bin(3);

    for i in 1 to width-1 loop

      out_gray(width-1-i) <= in_bin(width-i) xor in_bin(width-1-i);

    end loop;  -- i

  end process bin2gray_proc;

  -- i=1 out_gray(2) <= in_bin(3) xor in_bin(2);

  -- i=2 out_gray(1) <= in_bin(2) xor in_bin(1);

  -- i=3 out_gray(0) <= in_bin(1) xor in_bin(0);  

end behavior;