// File name	: adder.v
// OUT = A+B if select==0 and OUT=A-B if select==1;
module adder(select,A,B,OUT) ;
// adder/subtractor
parameter	LENGTH=5;
input			select;
input [LENGTH:1]	A,B;
output [LENGTH:1]	OUT;
assign 	OUT = (select)?(A-B):(A+B);
endmodule