38译码器

源代码:

`timescale 1ns / 1ps

module decode(a,b,c,out);
input a;
input b;
input c;
output reg[7:0] out;

always@(*)
begin
    case ({c,b,a})
         3'b000:out<=8'b00000001;
         3'b001:out<=8'b00000010;  
         3'b010:out<=8'b00000100;
         3'b011:out<=8'b00001000;  
         3'b100:out<=8'b00010000;
         3'b101:out<=8'b00100000;  
         3'b110:out<=8'b01000000;
         3'b111:out<=8'b10000000;    
    endcase      
end
endmodule

仿真代码：

`timescale 1ns / 1ps

module decode_tb();

reg a;
reg b;
reg c;
wire[7:0] out;
decode decode_inst(
                .a(a),
                .b(b),
                .c(c),
                .out(out)
);

initial begin
    a=0;
    b=0;
    c=0;

    #20
    a=1;
    b=0;
    c=0;

    #20
    a=0;
    b=1;
    c=0;

   #20
    a=1;
    b=1;
    c=0; 

     #20
    a=0;
    b=0;
    c=1;

    #20
    a=1;
    b=0;
    c=1;

    #20
    a=0;
    b=1;
    c=1;

   #20
    a=1;
    b=1;
    c=1;   

end

endmodule
`

仿真结果如下：