1

Behavioralmodule MUX4_to_1(y, x, s);

input x[3:0], s[1:0];output y;reg y;

always @(x or s) begin

if (s == 0)y=x[0];

else if …;end

endmodule

2

Continuous Assignmentmodule MUX4_to_1(y, x, s);

input x[3:0], s[1:0];output y;

assign y = (!s[0]&!s[1]&x[0]) | (!s[1]&s[0]&x[1]) |(s[0]&!s[1]&x[2]) | (s[1]&s[0]&x[3]);

endmodule

3

Structure module MUX4_to_1(y, x, s);

input x[3:0], s[1:0];output y;wire s1_, s0_, y0, y1, y2, y3; // optional

not(s1_, s1); not(s0_, s0);and(y0, s1_, s0_, x[0]);and(y1, s1_, s0, x[1]);

…or (y, y0, y1, y2, y3);

endmodule