//
//
//       DCS Tramitter Block Version 2.00 for FPGA/ASIC targets
//       Adrian Tang 2017
//
//      You need to clock at exactly the spreading-chip rate (IE 3.75 MS/s)
//      Verilog 2001
//
//      Typically a good PN code will be same number of 1s and 0s for minimal DC
//
//     Usage
//
//     1. Reset the block. 
//     2. As PN_codes are recgonized the bits they represent will be added to the output buffer
//     3. number_of_bits holds the current index of the output buffer
//        bits from output_buffer[0] to output_buffer[number_of_bits-1] are valid
//     4. They will be streamed out the USART


module DCS_spoof(reset, clk, track_stream, done);

//-----------------------------------------------------------------------------------------------------------------
//                            MTH SPREAD CODE SECTION
//-----------------------------------------------------------------------------------------------------------------
//MTH code flipped for reference: 1011101000001001100011110010101
//MTH code inverte for reference: 0100010111110110011100001101010
parameter PN_code = 31'b1010100111100011001000001011101;   //MTH Secret Spread Code

//-----------------------------------------------------------------------------------------------------------------
//                            COMMAND SECTION
//-----------------------------------------------------------------------------------------------------------------
//THIS IS THE DCS CODE WE WISH TO SEND
// THE DCS FORMAT GOES LIKE THIS 
// 11111111111111
// 0
// <ENGINE NUMBER +1 in LSB to MSB order> (Engine # 49 in this example)
// 1
// some command
// 111111111111111111
//Props to SanDiegoMark for helping me figure this out ... he's really really good at this!

//whistle code 11111111 11111110 01001100 10100000 00000000 01000000 01100011 11111111
parameter command_length = 8'd63;
parameter command = 64'b1111111111111110010011001010000000000000010000000110001111111111;  //whistle command?
//parameter command = 64'b1111111111111110010011001001000000000000000000000010001111111111;  //coupler command?


//Main Block Control
input clk;            //mater clock on the block (3.75 MS/s)
input reset;          //master reset for the block tripped after each packet

//Block Output
output track_stream;    //dsss stream from track
reg track_stream;

output done;
reg done;

//---------------------------Internal Counters------------------------------------------------
reg [5:0] spread_counter;  //Counts where we are in the spread code
reg [7:0] bit_counter;     //Counts where we are in the command



//------------------------------------------------------------------------------------------------------------------------------------------------------------------------
//                                                              MAIN CORRELATOR
//------------------------------------------------------------------------------------------------------------------------------------------------------------------------

always@ (posedge clk)
begin //always on clock synchronous ooperation
if(reset==0)   
    begin //if the block is in reset mode
    spread_counter<=6'd0;    //reset the spread counter         
    bit_counter<=command_length;   //Clear the output buffer         
    done <= 1'b0;
    end //reset=0 condition
else  
    begin
      if(done==1'b0)
         begin      
         //increment the spread chip counter every clock    
         spread_counter<=spread_counter+6'd1;
         //check to see which spread-chip we're on
         //invert it if the current byte is 0
         case(spread_counter)        
         6'd0:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[0];
            end
         else
            begin
            track_stream<=~PN_code[0];
            end
         end
         
          6'd1:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[1];
            end
         else
            begin
            track_stream<=~PN_code[1];
            end
         end
         
          6'd2:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[2];
            end
         else
            begin
            track_stream<=~PN_code[2];
            end
         end
         
      
           6'd3:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[3];
            end
         else
            begin
            track_stream<=~PN_code[3];
            end
         end
         
          6'd4:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[4];
            end
         else
            begin
            track_stream<=~PN_code[4];
            end
         end
         
      
           6'd5:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[5];
            end
         else
            begin
            track_stream<=~PN_code[5];
            end
         end
         
          6'd6:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[6];
            end
         else
            begin
            track_stream<=~PN_code[6];
            end
         end
         
      
           6'd7:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[7];
            end
         else
            begin
            track_stream<=~PN_code[7];
            end
         end
         
          6'd8:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[8];
            end
         else
            begin
            track_stream<=~PN_code[8];
            end
         end
         
          6'd9:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[9];
            end
         else
            begin
            track_stream<=~PN_code[9];
            end
         end
                                                              
         6'd10:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[10];
            end
         else
            begin
            track_stream<=~PN_code[10];
            end
         end
         
          6'd11:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[11];
            end
         else
            begin
            track_stream<=~PN_code[11];
            end
         end
         
          6'd12:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[12];
            end
         else
            begin
            track_stream<=~PN_code[12];
            end
         end
         
      
           6'd13:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[13];
            end
         else
            begin
            track_stream<=~PN_code[13];
            end
         end
         
          6'd14:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[14];
            end
         else
            begin
            track_stream<=~PN_code[14];
            end
         end
         
      
           6'd15:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[15];
            end
         else
            begin
            track_stream<=~PN_code[15];
            end
         end
         
          6'd16:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[16];
            end
         else
            begin
            track_stream<=~PN_code[16];
            end
         end
         
      
           6'd17:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[17];
            end
         else
            begin
            track_stream<=~PN_code[17];
            end
         end
         
          6'd18:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[18];
            end
         else
            begin
            track_stream<=~PN_code[18];
            end
         end
         
          6'd19:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[19];
            end
         else
            begin
            track_stream<=~PN_code[19];
            end
         end        
         
         
          6'd20:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[20];
            end
         else
            begin
            track_stream<=~PN_code[20];
            end
         end
         
          6'd21:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[21];
            end
         else
            begin
            track_stream<=~PN_code[21];
            end
         end
         
          6'd22:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[22];
            end
         else
            begin
            track_stream<=~PN_code[22];
            end
         end
         
      
           6'd23:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[23];
            end
         else
            begin
            track_stream<=~PN_code[23];
            end
         end
         
          6'd24:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[24];
            end
         else
            begin
            track_stream<=~PN_code[24];
            end
         end
         
      
           6'd25:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[25];
            end
         else
            begin
            track_stream<=~PN_code[25];
            end
         end
         
          6'd26:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[26];
            end
         else
            begin
            track_stream<=~PN_code[26];
            end
         end
         
      
           6'd27:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[27];
            end
         else
            begin
            track_stream<=~PN_code[27];
            end
         end
         
          6'd28:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[28];
            end
         else
            begin
            track_stream<=~PN_code[28];
            end
         end
         
          6'd29:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[29];
            end
         else
            begin
            track_stream<=~PN_code[29];
            end
         end         
         
        6'd30:
         begin
         if (command[bit_counter] == 1'b1) 
            begin
            track_stream<=PN_code[30];
            end
         else
            begin
            track_stream<=~PN_code[30];
            end
         end
         
          6'd31:
         begin
         bit_counter<=bit_counter-8'd1;
         spread_counter<=6'b0;
         if (bit_counter == 8'd0)
         begin
         done <=1'b1;
         track_stream<=0;
         end                         
         end         
         
   
         endcase

         end  //done =0 condition
         end  //reset =1 condition





end //on clock
endmodule