Remove named groups and simplify raw data usage.

[erlang-x-plane-data.git] / src / x_plane_data_raw.erl

diff --git a/src/x_plane_data_raw.erl b/src/x_plane_data_raw.erl
new file mode 100644 (file)
index 0000000..f419137
--- /dev/null
+++ b/src/x_plane_data_raw.erl
@@ -0,0 +1,86 @@
+-module(x_plane_data_raw).
+
+-export_type(
+    [ t/0
+    , index/0
+    , group_index/0
+    , group_values/0
+    , group/0
+    , groups/0
+    ]).
+
+-export(
+    [ of_bin/1
+    ]).
+
+-type parsing_error() ::
+      packet_bad_header
+    | packet_bad_length
+    .
+
+-type group_index() ::
+    non_neg_integer().
+
+-type group_values() ::
+    { float()
+    , float()
+    , float()
+    , float()
+    , float()
+    , float()
+    , float()
+    , float()
+    }.
+
+-type group() ::
+    {group_index(), group_values()}.
+
+% Packet index byte. Essentially a schema version.
+-type index() ::
+    integer().
+
+-type groups() ::
+    [group()].
+
+-type t() ::
+    {index(), groups()}.
+
+-define(BYTE_SIZE_OF_EACH_BLOCK, 36).
+-define(PACKET_HEADER, "DATA").
+
+-spec of_bin(binary()) ->
+      {ok, t()}
+    | {error, parsing_error()}
+    .
+of_bin(<<?PACKET_HEADER, _:8/integer, ContiguousBlocks/binary>>)
+    when byte_size(ContiguousBlocks) rem ?BYTE_SIZE_OF_EACH_BLOCK =/= 0 ->
+    {error, packet_bad_length};
+of_bin(<<?PACKET_HEADER, Index:8/integer, ContiguousBlocks/binary>>) ->
+    Groups = [group_of_bin(B) || B <- blocks_split(ContiguousBlocks)],
+    {ok, {Index, Groups}};
+of_bin(<<_/binary>>) ->
+    {error, packet_bad_header}.
+
+-spec blocks_split(binary()) ->
+    [binary()].
+blocks_split(<<>>) ->
+    [];
+blocks_split(<<Block:?BYTE_SIZE_OF_EACH_BLOCK/bytes, Blocks/binary>>) ->
+    [Block | blocks_split(Blocks)].
+
+-spec group_of_bin(binary()) ->
+    group().
+group_of_bin(
+    << Index:32/little-integer
+     ,    V1:32/little-float
+     ,    V2:32/little-float
+     ,    V3:32/little-float
+     ,    V4:32/little-float
+     ,    V5:32/little-float
+     ,    V6:32/little-float
+     ,    V7:32/little-float
+     ,    V8:32/little-float
+    >>
+) ->
+    Values = {V1, V2, V3, V4, V5, V6, V7, V8},
+    {Index, Values}.