hdb3.v

hdb3的发送端源代码

//***********************************************
//author  :           Zhang Yonggang
//data:               2007.5
//preject:            HDB3
//Email:              [e-mail]
//************************************************
module top(rst,sin,clk,hdb3); 
input           rst;
input           sin;
input           clk;
output [2:0]    hdb3; 
reg    [2:0]    hdb3; 
reg    [3:0]    in_buf;
reg             ou;     
reg             fu;     
reg    [2:0]    vshow;   
reg             vpose;   
reg             data;
parameter  
          Vp   =     3'b111,  
          Bp   =     3'b110,  
          Hp   =     3'b101,  
          Zero =     3'b100,  
          Hn   =     3'b011,  
          Bn   =     3'b010,    
          Vn   =     3'b001;  
//////////////////////////////////////
always @(negedge rst or posedge clk)
if(~rst)
     in_buf     <=4'h0;
else
     in_buf     <={in_buf[2:0],sin}; 

//////////////////////////////////////
always @(negedge rst or negedge clk)
if(~rst)
     begin
     ou     <=0;
     fu     <=0; 
     vshow  <=3'b000;
     vpose  <=0; 
     data   <=0;
     end
else 
begin
     data<=in_buf[3];
  if(in_buf[3]==0)      //0xxx
        if( vshow==3'b010)    //x000 0xxx  it's time to make v
               begin
                 vshow  <= vshow +1;
               if(vpose) 
                  begin
                  hdb3  <=Vn;
                  fu    <=1;                  
                  end
               else  
                  begin
                  hdb3  <=Vp; 
                  fu    <=0;
                  end      
               end
        else  //  make b time 
          if( in_buf==4'h0 )
            if( vshow==3'b111)    
               begin
                  vshow  <=3'b000; 
                  vpose  <=~vpose;
                  fu     <=~vpose; 
                  ou     <=1;
                  if(ou) 
                      if(fu) 
                         hdb3  <=Bp;
                      else
                         hdb3  <=Bn;
                  else  
                      hdb3  <=Zero;
               end 
             else
                begin 
                hdb3   <=Zero; 
                if(vshow <3'b110)
                   vshow  <= vshow +1;
                else
                   vshow  <=3'b110;
                end  
         else
                begin 
                hdb3   <=Zero; 
                if(~vshow[2])
                   vshow  <= vshow +1;
                else
                   vshow  <=3'b110;
                end  
else       //1xxx
     begin
      vshow   <=3'b111;
      fu      <=~fu; 
      ou      <=~ou;
     if(fu)
           hdb3  <=Hp; 
      else
           hdb3  <=Hn; 
     end     
end                       
endmodule
//********************************************