always @(posedge clk) begin : MyROM
    if (en)
        case (addr)
            4'b0000 : data <= 8'h02;
            4'b0001 : data <= 8'h22;
            4'b0010 : data <= 8'hdd;
               ... 
            4'b1111 : data <= 8'h0d;
        endcase
end