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`include "../bench/timescale.v"

// this file implement the stream cypher module

module stream_cypher(clk,rst,en,init,ck,sb,cb);

input                 clk;

input                 rst;   // hi enable

input                 en;      // hi enable

input                 init;    // hi enable

input  [8 *8-1:0]     ck;

input  [8 *8-1:0]     sb;

output [8 *8-1:0]     cb;

// intermediate variable

reg    [10*4-1 : 0]A;

reg    [10*4-1 : 0]B;

reg    [4-1    : 0]X;

reg    [4-1    : 0]Y;

reg    [4-1    : 0]Z;

reg    [4-1    : 0]D;

reg    [4-1    : 0]E;

reg    [4-1    : 0]F;

reg                p;

reg                q;

reg                r;

wire   [10*4-1 : 0]Ao;

wire   [10*4-1 : 0]Ainit;

wire   [10*4-1 : 0]Bo;

wire   [10*4-1 : 0]Binit;

wire   [4-1    : 0]Xo;

wire   [4-1    : 0]Yo;

wire   [4-1    : 0]Zo;

wire   [4-1    : 0]Do;

wire   [4-1    : 0]Eo;

wire   [4-1    : 0]Fo;

wire               po;

wire               qo;

wire               ro;

wire   [8 *8-1 : 0]cbo;

assign Ainit = {

                4'b0,         4'b0,

        ck[7*4-1:6*4],ck[8*4-1:7*4],

        ck[5*4-1:4*4],ck[6*4-1:5*4],

        ck[3*4-1:2*4],ck[4*4-1:3*4],

        ck[1*4-1:0*4],ck[2*4-1:1*4]

};

assign Binit = {

                   4'b0,           4'b0,

        ck[15*4-1:14*4],ck[16*4-1:15*4],

        ck[13*4-1:12*4],ck[14*4-1:13*4],

        ck[11*4-1:10*4],ck[12*4-1:11*4],

        ck[ 9*4-1: 8*4],ck[10*4-1: 9*4]

};

always @(posedge clk)

begin

        if(rst)

        begin

                A<= 40'h0000000000;

                B<= 40'h0000000000;

                X<=  4'h0;

                Y<=  4'h0;

                Z<=  4'h0;

                D<=  4'h0;

                E<=  4'h0;

                F<=  4'h0;

                p<=  1'h0;

                q<=  1'h0;

                r<=  1'h0;

        end

        else

        begin

                if(en)

                begin

                        A<=  Ao;

                        B<=  Bo;

                        X<=  Xo;

                        Y<=  Yo;

                        Z<=  Zo;

                        D<=  Do;

                        E<=  Eo;

                        F<=  Fo;

                        p<=  po;

                        q<=  qo;

                        r<=  ro;

                end

        end

end

stream_8bytes stream_8bytes(

                        .init(init)

                       ,.sb(sb)

                       ,.Ai((init)?Ainit:A)

                       ,.Bi((init)?Binit:B)

                       ,.Di((init)?4'b0 :D)

                       ,.Ei((init)?4'b0 :E)

                       ,.Fi((init)?4'b0 :F)

                       ,.Xi((init)?4'b0 :X)

                       ,.Yi((init)?4'b0 :Y)

                       ,.Zi((init)?4'b0 :Z)

                       ,.pi((init)?1'b0 :p)

                       ,.qi((init)?1'b0 :q)

                       ,.ri((init)?1'b0 :r)

                       ,.Ao(Ao)

                       ,.Bo(Bo)

                       ,.Do(Do)

                       ,.Eo(Eo)

                       ,.Fo(Fo)

                       ,.Xo(Xo)

                       ,.Yo(Yo)

                       ,.Zo(Zo)

                       ,.po(po)

                       ,.qo(qo)

                       ,.ro(ro)

                       ,.cb(cbo)

                );

        assign cb=cbo;

endmodule