module gray2bin (gray, bin); 
 parameter SIZE = 4; 
 input  [SIZE-1:0] gray; 
 output [SIZE-1:0] bin; 
 reg [SIZE-1:0] bin;
 integer i;
 always @(gray) for (i=0;i<SIZE;i=i+1) bin[i] = ^(gray >> i);
endmodule