//2023-10-26  姜青羊
//case语句实现多路选择逻辑  ,tb写的更简便一些


/*module tb_fn_sw ();

reg                 aa,bb,ss;
wire                yy;

initial begin
                    ss = 2'b00; aa = 0; bb = 0;
        #10         ss = 2'b00; aa = 0; bb = 1;
        #10         ss = 2'b00; aa = 1; bb = 0;
        #10         ss = 2'b00; aa = 1; bb = 1;
        #10         ss = 2'b01; aa = 0; bb = 0;
        #10         ss = 2'b01; aa = 0; bb = 1;
        #10         ss = 2'b01; aa = 1; bb = 0;
        #10         ss = 2'b01; aa = 1; bb = 1;
        #10         ss = 2'b10; aa = 0; bb = 0;
        #10         ss = 2'b10; aa = 0; bb = 1;
        #10         ss = 2'b10; aa = 1; bb = 0;
        #10         ss = 2'b10; aa = 1; bb = 1;
        #10         ss = 2'b11; aa = 0; bb = 0;
        #10         ss = 2'b11; aa = 0; bb = 1;
        #10         ss = 2'b11; aa = 1; bb = 0;
        #10         ss = 2'b11; aa = 1; bb = 1;
                    $stop;
end


fn_sw u_fn_sw (
                    .a(aa),
                    .b(bb),
                    .sel(ss),
                    .y(yy)
             );

endmodule
*/


module tb_fn_sw ();

reg[3:0]                absel;
wire                    yy;

initial begin
                        absel = 4'b0000;
            #200        $stop;
end

always #10              absel = absel+1;


fn_sw u_fn_sw (
                    .a(aa),
                    .b(bb),
                    .sel(ss),
                    .y(yy)
             );

endmodule