Sample X10 packet (de)composition in Elixir

x10.ex

defmodule X10 do
  # all codes referenced from http://www.haibrain.com/informatie-domotica-x10-protocol-c-131_148_141.html?language=en

  @house_codes %{
    6  => :house_a,
    14 => :house_b,
    2  => :house_c,
    10 => :house_d,
    1  => :house_e,
    9  => :house_f,
    5  => :house_g,
    13 => :house_h,
    7  => :house_i,
    15 => :house_j,
    3  => :house_k,
    11 => :house_l,
    0  => :house_m,
    8  => :house_n,
    4  => :house_o,
    12 => :house_p,
  }

  @unit_codes %{
    12 => :unit_1,
    28 => :unit_2,
    4  => :unit_3,
    20 => :unit_4,
    2  => :unit_5,
    18 => :unit_6,
    10 => :unit_7,
    16 => :unit_8,
    14 => :unit_9,
    30 => :unit_10,
    6  => :unit_11,
    22 => :unit_12,
    0  => :unit_13,
    16 => :unit_14,
    8  => :unit_15,
    24 => :unit_16,
  }

  @function_codes %{
    1  => :all_units_off,
    3  => :all_lights_on,
    5  => :on,
    7  => :off,
    9  => :dim,
    11 => :bright,
    15 => :extended_code,
    17 => :hail_request,
    19 => :hail_acknowledge,
    21 => :preset_dim,
    25 => :extended_data,
    25 => :extended_data,
    27 => :status_on,
    29 => :status_off,
    31 => :status_request,
  }

  for {code, letter} <- @house_codes do
    def parse_house_code(unquote(code)), do: unquote(letter)
    def construct_code(unquote(letter)), do: unquote(code)
  end
  for {code, command} <- @function_codes do
    def parse_function_code(unquote(code)), do: unquote(command)
    def construct_code(unquote(command)), do: unquote(code)
  end
  for {code, unit} <- @unit_codes do
    def parse_function_code(unquote(code)), do: unquote(unit)
    def construct_code(unquote(unit)), do: unquote(code)
  end


  def parse_packet(<<14::size(4), house_code::size(4), other::size(5)>>) do
    {parse_house_code(house_code), parse_function_code(other)}
  end

  def create_packet({house, function}) do
    house_code = construct_code(house)
    function_code = construct_code(function)
    <<14::size(4), house_code::size(4), function_code::size(5)>>
  end
end