src/x_plane_data_raw.erl

   1 -module(x_plane_data_raw).
   2
   3 -export_type(
   4     [ t/0
   5     , index/0
   6     , group_index/0
   7     , group_values/0
   8     , group/0
   9     , groups/0
  10     ]).
  11
  12 -export(
  13     [ of_bin/1
  14     ]).
  15
  16 -type parsing_error() ::
  17       packet_bad_header
  18     | packet_bad_length
  19     .
  20
  21 -type group_index() ::
  22     non_neg_integer().
  23
  24 -type group_values() ::
  25     { float()
  26     , float()
  27     , float()
  28     , float()
  29     , float()
  30     , float()
  31     , float()
  32     , float()
  33     }.
  34
  35 -type group() ::
  36     {group_index(), group_values()}.
  37
  38 % Packet index byte. Essentially a schema version.
  39 -type index() ::
  40     integer().
  41
  42 -type groups() ::
  43     [group()].
  44
  45 -type t() ::
  46     {index(), groups()}.
  47
  48 -define(BYTE_SIZE_OF_EACH_BLOCK, 36).
  49 -define(PACKET_HEADER, "DATA").
  50
  51 -spec of_bin(binary()) ->
  52       {ok, t()}
  53     | {error, parsing_error()}
  54     .
  55 of_bin(<<?PACKET_HEADER, _:8/integer, ContiguousBlocks/binary>>)
  56     when byte_size(ContiguousBlocks) rem ?BYTE_SIZE_OF_EACH_BLOCK =/= 0 ->
  57     {error, packet_bad_length};
  58 of_bin(<<?PACKET_HEADER, Index:8/integer, ContiguousBlocks/binary>>) ->
  59     Groups = [group_of_bin(B) || B <- blocks_split(ContiguousBlocks)],
  60     {ok, {Index, Groups}};
  61 of_bin(<<_/binary>>) ->
  62     {error, packet_bad_header}.
  63
  64 -spec blocks_split(binary()) ->
  65     [binary()].
  66 blocks_split(<<>>) ->
  67     [];
  68 blocks_split(<<Block:?BYTE_SIZE_OF_EACH_BLOCK/bytes, Blocks/binary>>) ->
  69     [Block | blocks_split(Blocks)].
  70
  71 -spec group_of_bin(binary()) ->
  72     group().
  73 group_of_bin(
  74     << Index:32/little-integer
  75      ,    V1:32/little-float
  76      ,    V2:32/little-float
  77      ,    V3:32/little-float
  78      ,    V4:32/little-float
  79      ,    V5:32/little-float
  80      ,    V6:32/little-float
  81      ,    V7:32/little-float
  82      ,    V8:32/little-float
  83     >>
  84 ) ->
  85     Values = {V1, V2, V3, V4, V5, V6, V7, V8},
  86     {Index, Values}.