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-- Two Galois multiplication functions based on http://www.isaakian.com/VHDL/AES/.

library ieee;

use IEEE.STD_LOGIC_1164.ALL;

use IEEE.std_logic_ARITH.ALL;

use IEEE.std_logic_UNSIGNED.ALL;

package aes_lib is

  function gfmult2 (

     I : std_logic_vector(7 downto 0))

    return std_logic_vector;

  function gfmult3 (

     I : std_logic_vector(7 downto 0))

    return std_logic_vector;

end aes_lib;

package body aes_lib is

    function gfmult2 (

     I : std_logic_vector(7 downto 0))

    return std_logic_vector is

      variable  result : std_logic_vector(7 downto 0);

    begin

      result := (I(6 downto 0) & '0') xor (x"1B" and ("000" & I(7)& I(7) & "0" & I(7)& I(7)));

      return result;

    end gfmult2;

    function gfmult3 (

     I : std_logic_vector(7 downto 0))

    return std_logic_vector is

      variable result : std_logic_vector(7 downto 0);

    begin

      result := gfmult2(I) xor I;

      return result;

    end gfmult3;

end aes_lib;