MUX2:1与MUX4:1的代码（源自于NV-ASIC Physical design笔试题目）

MUX2:1实现二选一选的功能

module MUX2_1(        input x0,        input x1，        input sel，        output y0，        reg y0_out ); always(*)   begin      case(sel)      1'b0:y0_out=x0;      1'b1:y0_out=x1;      default:y0_out=x0;      endcase  end assign y0=y0_out; endmodule 

MUX4:1四选一选择器采用二选一模块实现(以下为自己设计，如有不对请多指正)

module MUX4_1(        input a0,        input a1,        input a2,        input a3,        input a4,        input a5,        input sel0,        input sel1,        input sel2,        output b0,        output b1,        output b2,        output b_out ); MUX2_1 first(.x0(a0),.x1(a1),.sel(sel0),.y0(b0)); MUX2_1 second(.x0(a2),.x1(a3),.sel(sel1),.y0(b1)); assign sel2=sel1 sel0; MUX2_1 third(.x0(b0),.(b1),.sel(sel2),.y0(b2)); assign b_out=b2; endmodule