CODEWITHSUNDEEP
debuggingverilogsystem-verilog
Aliyar Attaran
Aliyar Attaran

Reputation: 41

Verilog code motion estimator

I having trouble with finding the smallest values of X and xfind and Y and yfind in `Costcalculator xfind (X,xcost); Costcalculator yfind (Y,ycost);

in code below. can someone comment please. For some reason I couldn't import the whole code. It just recognizes these lines as codes. Sorry if it is not clear.

  always @(posedge clk)   // sequential circuit

  begin

    Costcalculator xfind (X,xcost);
    Costcalculator yfind (Y,ycost); 

    if(reset)
      begin 
        i=0;
        R<=0;
        xcost<=0;
        ycost<=0;
        mode0<=0;
        mode1<=0;
        mode2<=0;
        mode3<=0;
        mode4<=0;
        mode5<=0;
        mode6<=0;
      end   //if end
        else
      begin
            for (i=1; i<43;  i=i+1)
      begin
               R<=xcost+ycost;
         costholder <= SAD+(lambda*R);   // Here we calculate the cost of a sub-blocks As the clock
                if (i<17)
         mode0<=costholder+mode0;
       else if(i>16 && i<25)
         mode1<=costholder+mode1;
       else if(i>24 && i<33) 
         mode2<=costholder+mode2;
       else if(i==33 || i==34 || i==35 || i==36 )
         mode3<=costholder+mode3;
       else if(i==37 || i==38)
         mode4<=costholder+mode4;
       else if(i==39 || i==40)
         mode5<=costholder+mode5;
       else if(i==41)
         mode6<=costholder+mode6;

       end    //for end
    end   //else end
  end   //always end

Module Costcalculator:

//**********************************************************‌​** 
module Costcalculator (motionvector, cost); // X AND Y COST CALCULATOR 
input [4:0]motionvector; 
output [2:0]cost; 
reg [2:0]cos; 
wire [3:0] vector; 
assign vector = {motionvector[3:0] }; 

always @* begin 
case (vector) 0 : cos=0; 
1,2 : cos=1; 
3,4,5,6 : cos=2; 
7,8,9,10,11,12,13,14 : cos=3; 
15 : cos=4; 
endcase 
end 
assign cost = cos; 
endmodule 
//**********************************************************‌​**

Upvotes: 0

Views: 307

Answers (1)

sharvil111
sharvil111

Reputation: 4381

After taking the module outside the always block, you are driving xconst and yconst from two places. On the other hand, I don't see drivers of X and Y.

Since Costcalculator is a purely combinational module, you need to just provide the inputs X and Y as zero from the top/wrapper module.

//.. some stuff
if(reset) begin
//... some other signals
X <= 0;
Y <=0;
//...

As the error says about multiple drivers, you are driving xconst and yconst form two modules. On reset, if you provide X and Y as 0 from the wrapping module, then automatically the vector will go to Zero and ultimately the cost which is the output of module will become Zero. Thereby the variables xconst and yconst will become zero.

Refer to this similar forum question for more information.

Upvotes: 1

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