Behavioral Description

BEHAVIORAL DESCRIPTION 

module encoder8_3 (y, I);

  input  [7:0] I;

  output [2:0] y;

  reg    [2:0] y;

  always @(I)

  begin

    case (I)

      8'b0000_0001: y = 3'b000;

      8'b0000_0010: y = 3'b001;

      8'b0000_0100: y = 3'b010;

      8'b0000_1000: y = 3'b011;

      8'b0001_0000: y = 3'b100;

      8'b0010_0000: y = 3'b101;

      8'b0100_0000: y = 3'b110;

      8'b1000_0000: y = 3'b111;

      default:      y = 3'bxxx;  // undefined if multiple inputs high

    endcase

  end

endmodule

Test Bench:--

module tb_encoder8_3;

  reg  [7:0] I;

  wire [2:0] y;

  // Instantiate the 8:3 encoder

  encoder8_3 uut (.y(y), .I(I));

  initial

  begin

    I = 8'b0000_0001;  // input 0

    #10 I = 8'b0000_0010;  // input 1

    #10 I = 8'b0000_0100;  // input 2

    #10 I = 8'b0000_1000;  // input 3

    #10 I = 8'b0001_0000;  // input 4

    #10 I = 8'b0010_0000;  // input 5

    #10 I = 8'b0100_0000;  // input 6

    #10 I = 8'b1000_0000;  // input 7

    #20 $finish;

  end

endmodule

OUTPUT