Subversion Repositories aes_decry_ip_128bit

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

--Copyright 2015, Ganesh Hegde < ghegde@opencores.org >      

--                                                           

--This source file may be used and distributed without  

--restriction provided that this copyright statement is not 

--removed from the file and that any derivative work contains

--the original copyright notice and the associated disclaimer.

--

--This source 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 Lesser General Public License for more

--details.

--

--You should have received a copy of the GNU Lesser General

--Public License along with this source; if not, download it

--from http://www.opencores.org/lgpl.shtml

--

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

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

--This module will perform byte substitution for the given input word.

--Logic type : Combinational

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

library ieee;

use ieee.std_logic_1164.all;

entity Sub_4bytes is

port(

     word_in: in std_logic_vector(31 downto 0);

         word_out: out std_logic_vector(31 downto 0)

     );

end Sub_4bytes;

architecture Sub_4bytes_beh of Sub_4bytes is

   signal b0,b1,b2,b3: std_logic_vector(7 downto 0);

   component Sbox

   port (

        data_in: in std_logic_vector(7 downto 0);

        data_out:out std_logic_vector(7 downto 0)

   );

   end component;

begin

   b0<=word_in(31 downto 24);

   b1<=word_in(23 downto 16);

   b2<=word_in(15 downto 8);

   b3<=word_in(7 downto 0);

   Inst1:Sbox

      port map(data_in=>b0,data_out=>word_out(31 downto 24));

   Inst2:Sbox

      port map(data_in=>b1,data_out=>word_out(23 downto 16));

   Inst3:Sbox

      port map(data_in=>b2,data_out=>word_out(15 downto 8));

   Inst4:Sbox

      port map(data_in=>b3,data_out=>word_out(7 downto 0));

end Sub_4bytes_beh;