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library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
package aes_pkg is
type t_usig_1d is array(natural range <>) of unsigned(7 downto 0);
type t_usig_2d is array(natural range <>, natural range <>) of unsigned(7 downto 0);
constant C_STATE_ROWS : integer := 2;
constant C_STATE_COLS : integer := 2;
subtype st_word is t_usig_1d(0 to C_STATE_COLS - 1);
subtype st_state is t_usig_2d(0 to C_STATE_ROWS - 1, 0 to C_STATE_COLS - 1);
subtype st_sbox is t_usig_1d(0 to 255);
type t_key is array(natural range <>) of st_word;
function mix_columns (a_in : st_state) return st_state;
end package aes_pkg;
package body aes_pkg is
-- FIPS 197, 5.1.3 MixColumns() Transformation
function mix_columns (a_in : st_state) return st_state is
variable a_out : st_state;
begin
for col in 0 to C_STATE_COLS - 1 loop
a_out(0, col) := a_in(0, col) xor
a_in(1, col);
a_out(1, col) := a_in(0, col) xor
a_in(1, col);
end loop;
return a_out;
end mix_columns;
end package body;
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