module mult (input clock, input signed [15:0] x, input signed [15:0] y, output reg signed [30:0] product,
	     input enable_in, output reg enable_out );

   always @(posedge clock)
     if(enable_in)
       product <= #1 x*y;
     else
       product <= #1 31'd0;
   
   always @(posedge clock)
     enable_out <= #1 enable_in;
   
endmodule // mult