20150109_KUAS_Verilog_HammingCode

module HammingCode(_in, Decode, Encode, Reset, _out, _led);
    input       [4:0] _in;
    input       Decode, Encode, Reset;
    output      [6:0] _out;
    output reg  [4:0] _led;

    reg     [8:0] HammingCode;
    reg     [3:0] XorCode;

    //At the first, remember to click Reset button.
    always@(negedge Encode, negedge Decode, negedge Reset) begin
        if(Reset == 0) begin
            HammingCode = 0;
            XorCode = 0;
            _led = 5'b00000;
        end

        else
            if(Encode == 0) begin
                XorCode = 0;
                HammingCode[8] = _in[4];
                HammingCode[6] = _in[3];
                HammingCode[5] = _in[2];
                HammingCode[4] = _in[1];
                HammingCode[2] = _in[0];
                _led = {HammingCode[8], HammingCode[6], HammingCode[5], HammingCode[4], HammingCode[2]};

                if(HammingCode[8] == 1'b1)
                    XorCode = XorCode ^ 4'b1001;
                if(HammingCode[6] == 1'b1)
                    XorCode = XorCode ^ 4'b0111;
                if(HammingCode[5] == 1'b1)
                    XorCode = XorCode ^ 4'b0110;
                if(HammingCode[4] == 1'b1)
                    XorCode = XorCode ^ 4'b0101;
                if(HammingCode[2] == 1'b1)
                    XorCode = XorCode ^ 4'b0011;

                HammingCode[7] = XorCode[3];
                HammingCode[3] = XorCode[2];
                HammingCode[1] = XorCode[1];
                HammingCode[0] = XorCode[0];
            end

            else if(Decode == 0) begin
                XorCode = 0;
                HammingCode[8] = _in[4];
                HammingCode[6] = _in[3];
                HammingCode[5] = _in[2];
                HammingCode[4] = _in[1];
                HammingCode[2] = _in[0];
                if(HammingCode[8] == 1'b1)
                    XorCode = XorCode ^ 4'b1001;
                if(HammingCode[7] == 1'b1)
                    XorCode = XorCode ^ 4'b1000;
                if(HammingCode[6] == 1'b1)
                    XorCode = XorCode ^ 4'b0111;
                if(HammingCode[5] == 1'b1)
                    XorCode = XorCode ^ 4'b0110;
                if(HammingCode[4] == 1'b1)
                    XorCode = XorCode ^ 4'b0101;
                if(HammingCode[3] == 1'b1)
                    XorCode = XorCode ^ 4'b0100;
                if(HammingCode[2] == 1'b1)
                    XorCode = XorCode ^ 4'b0011;
                if(HammingCode[1] == 1'b1)
                    XorCode = XorCode ^ 4'b0010;
                if(HammingCode[0] == 1'b1)
                    XorCode = XorCode ^ 4'b0001;
            end
    end
    Seven_Change    tmp (XorCode, _out);
endmodule

module Seven_Change(in, out);
    input           [3:0]   in;
    output reg  [6:0]   out;
    always@(in)
    begin
        case(in)
            // 0
            4'b0000: out = 7'b1000000;
            // 1
            4'b0001: out = 7'b1111001;
            // 2
            4'b0010: out = 7'b0100100;
            // 3
            4'b0011: out = 7'b0110000;
            // 4
            4'b0100: out = 7'b0011001;
            // 5
            4'b0101: out = 7'b0010010;
            // 6
            4'b0110: out = 7'b0000010;
            // 7
            4'b0111: out = 7'b1111000;
            // 8
            4'b1000: out = 7'b0000000;
            // 9
            4'b1001: out = 7'b0011000;
            // A
            4'b1010: out = 7'b0001000;
            // b
            4'b1011: out = 7'b0000011;
            // C
            4'b1100: out = 7'b1000110;
            // d
            4'b1101: out = 7'b0100001;
            // E
            4'b1110: out = 7'b0000110;
            // F
            4'b1111: out = 7'b0001110;
        endcase
    end
endmodule