使用移位實現：

module decoder(out ,in);
	output [7:0 ] out ;
	input [2:0] in;
	
	assign out = 1'b1 << in;
	endmodule 
	

使用case實現：

module decoder1(out,in);
	output [2:0] out;
	input [7:0] in;
	
	reg [2:0] out;


	
	always @(in)
		begin 
			 case (in)
			 3'b000:	out <= 8'b0000_0001;
			 
			 3'b001:	out <= 8'b0000_0010;
			 3'b010:	out <= 8'b0000_0100;
			 3'b011:	out <= 8'b0000_1000;
			 3'b100:	out <= 8'b0001_0000;
			 
			 3'b101:	out <= 8'b0010_0000;
			 3'b110:	out <= 8'b0100_0000;
			 3'b111:	out <= 8'b1000_0000;


			 default:out <= 8'bz;
			 endcase 
		end
	endmodule