MixColumnInv.v

`timescale 1ns / 1ps
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// Company: 
// Engineer: 
// 
// Create Date:    20:27:32 10/22/2017 
// Design Name: 
// Module Name:    MixColumnInv 
// Project Name: 
// Target Devices: 
// Tool versions: 
// Description: 
//
// Dependencies: 
//
// Revision: 
// Revision 0.01 - File Created
// Additional Comments: 
//
//////////////////////////////////////////////////////////////////////////////////
module MixColumnsInv(input [127 : 0] data, output reg [127:0] inv_mixcolumns);
    reg [31 : 0] w0, w1, w2, w3;
    reg [31 : 0] ws0, ws1, ws2, ws3;
	 
	 function [7 : 0] gm2(input [7 : 0] op);
    begin
      gm2 = {op[6 : 0], 1'b0} ^ (8'h1b & {8{op[7]}});
    end
  endfunction // gm2

  function [7 : 0] gm3(input [7 : 0] op);
    begin
      gm3 = gm2(op) ^ op;
    end
  endfunction // gm3

  function [7 : 0] gm4(input [7 : 0] op);
    begin
      gm4 = gm2(gm2(op));
    end
  endfunction // gm4

  function [7 : 0] gm8(input [7 : 0] op);
    begin
      gm8 = gm2(gm4(op));
    end
  endfunction // gm8

  function [7 : 0] gm09(input [7 : 0] op);
    begin
      gm09 = gm8(op) ^ op;
    end
  endfunction // gm09

  function [7 : 0] gm11(input [7 : 0] op);
    begin
      gm11 = gm8(op) ^ gm2(op) ^ op;
    end
  endfunction // gm11

  function [7 : 0] gm13(input [7 : 0] op);
    begin
      gm13 = gm8(op) ^ gm4(op) ^ op;
    end
  endfunction // gm13

  function [7 : 0] gm14(input [7 : 0] op);
    begin
      gm14 = gm8(op) ^ gm4(op) ^ gm2(op);
    end
endfunction
	 
	 function [31 : 0] inv_mixw(input [31 : 0] w);
    reg [7 : 0] b0, b1, b2, b3;
    reg [7 : 0] mb0, mb1, mb2, mb3;
    begin
      b0 = w[31 : 24];
      b1 = w[23 : 16];
      b2 = w[15 : 08];
      b3 = w[07 : 00];

      mb0 = gm14(b0) ^ gm11(b1) ^ gm13(b2) ^ gm09(b3);
      mb1 = gm09(b0) ^ gm14(b1) ^ gm11(b2) ^ gm13(b3);
      mb2 = gm13(b0) ^ gm09(b1) ^ gm14(b2) ^ gm11(b3);
      mb3 = gm11(b0) ^ gm13(b1) ^ gm09(b2) ^ gm14(b3);

      inv_mixw = {mb0, mb1, mb2, mb3};
    end
	 endfunction
	 always
    begin
      w0 = data[127 : 096];
      w1 = data[095 : 064];
      w2 = data[063 : 032];
      w3 = data[031 : 000];

      ws0 = inv_mixw(w0);
      ws1 = inv_mixw(w1);
      ws2 = inv_mixw(w2);
      ws3 = inv_mixw(w3);

      inv_mixcolumns = {ws0, ws1, ws2, ws3};
    end
endmodule