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// this module is used to computer a key

// author: Simon panti

//          mengxipeng@gmail.com

// refer:

//                      cas.c in vlc opensource project

module key_computer(cw,key);

                input   [63:0]   cw;

                output  [447:0]  key;

                wire    [63:0]   key1;

                wire    [63:0]   key2;

                wire    [63:0]   key3;

                wire    [63:0]   key4;

                wire    [63:0]   key5;

                wire    [63:0]   key6;

                wire    [63:0]   key7;

                key_perm kp0 (   cw, key7 );

                key_perm kp1 ( key7, key6 );

                key_perm kp2 ( key6, key5 );

                key_perm kp3 ( key5, key4 );

                key_perm kp4 ( key4, key3 );

                key_perm kp5 ( key3, key2 );

                key_perm kp6 ( key2, key1 );

                assign key[64*1-1:64*0]=key2 ^ 64'h0000000000000000;

                assign key[64*2-1:64*1]=key3 ^ 64'h0101010101010101;

                assign key[64*3-1:64*2]=key4 ^ 64'h0202020202020202;

                assign key[64*4-1:64*3]=key5 ^ 64'h0303030303030303;

                assign key[64*5-1:64*4]=key6 ^ 64'h0404040404040404;

                assign key[64*6-1:64*5]=key7 ^ 64'h0505050505050505;

                assign key[64*7-1:64*6]=cw   ^ 64'h0606060606060606;

endmodule