module alu_4b (iS,iA,iB,oY);
input[1:0] iS;
input[3:0] iA,iB;
output[3:0] oY;
wire[3:0] oY, tY0, tY1, tY2, tY3;
wire tD0, tD1;
add_4b a_add (1'b0,iA,iB,tD0,tY0);
sub_4b a_sub (1'b0,iA,iB,tD1,tY1);
and_4b l_and (iA,iB,tY2);
or_4b l_or (iA,iB,tY3);
defparam omux.BITS = 4;
dmux41 omux (iS,tY0,tY1,tY2,tY3,oY);
endmodule