verilog实现两个数的最大公因数

 module gcd(clk,clr,go_i,x_i,y_i,d_o);
 input clk,clr;
 input go_i;
 input[:] x_i,y_i;
 output reg[:] d_o;
 reg[:] x,y,r;
 always@(posedge clk, posedge clr)
  if(clr)
  begin
  x=;y=;d_o=;
  end
 else
 begin
 if(go_i)
  begin
  if(x_i<y_i) begin x=y_i; y=x_i; end
  else begin x=x_i; y=y_i; end
  end
  else
  begin
  if(!y)
  begin d_o=x; end
  else
  begin r=x%y; x=y; y=r; end
  end
  end
 endmodule