xplane.erl

-module(xplane).

-compile(export_all).

start() ->
    {ok, Socket} = gen_udp:open(48000,[binary]),
    %receive
    %    after 1000 ->
    %        control_throttle(Socket)
    %end,
    loop(Socket,1).
    
    
loop(Socket,Count) ->
    io:format("~p~n",[Count]),
    receive
        {udp, Socket, IP, InPortNo, Packet} when Count > 0 ->
            print_packet(Socket,IP,InPortNo,Packet),
            control_throttle(Socket),
            loop(Socket, Count -1)
    after 1000 ->
        gen_udp:close(Socket),
        exit(done)
    end.
    
print_packet(Socket,IP,InPortNo,Packet) ->
    io:format("Socket: ~p~n",[Socket]),
    io:format("IP: ~p~n",[IP]),
    io:format("InPortNo: ~p~n",[InPortNo]),
    io:format("Packet: ~p~n",[Packet]),
    io:format("   ~p~n",[parse_packet(Packet)]).

parse_packet(<<"DATA",_:1/binary, DataSets/binary>>) ->
    parse_datasets(DataSets).

parse_datasets(DataSets) ->
    parse_datasets(DataSets,[]).    
parse_datasets(<<DataSet:36/binary,Rest/binary>>,Acc) ->
    parse_datasets(Rest,[parse_dataset(DataSet) | Acc]);
parse_datasets(<<>>,Acc) ->
    lists:reverse(Acc).
    
parse_dataset(<<DataSet/integer,_:3/binary,ValuesBlock:32/binary>>) ->
    {DataSet,parse_values(ValuesBlock)}.

parse_values(Values) ->
    parse_values(Values,[]).
parse_values(<<Value:32/native-float,Rest/binary>>,Acc) ->
    parse_values(Rest,[Value | Acc]);
parse_values(<<>>,Acc) ->
    lists:reverse(Acc).
    

control_throttle(Socket) ->
    gen_udp:send(Socket,"127.0.0.1",49000,override_packet()),
    gen_udp:send(Socket,"127.0.0.1",49000,throttle_packet()).
    
override_packet() ->
    DataRef = <<"sim/operation/override/override_throttles">>,
    Value = 1.0,
    Packet = <<"DREF",0,Value:32/native-float,DataRef/binary>>,
    io:format("Sending: ~p~n",[Packet]),
    Padding = 8 * (509 - size(Packet)),
    <<Packet/binary,0:Padding>>.

throttle_packet() ->
    DataRef = <<"sim/flightmodel/engine/ENGN_thro_override">>,
    Value = 0.5,
    Packet = <<"DREF",0,Value:32/native-float,DataRef/binary>>,
    io:format("Sending: ~p~n",[Packet]),
    Padding = 8 * (509 - size(Packet)),
    <<Packet/binary,0:Padding>>.

xplane.rb

require 'pp'

require 'rubygems'
require 'eventmachine'

module XplaneServer

  def post_init
  end

  def data_struct
    "l f8"
  end
  
  def pack_str
    "a4 C #{data_struct} a*" # message internal-index data-index 8-floats other
  end
 
 
  def receive_data data
    # unpacks the first element. further unpack(data_struct) calls will grab each additional
    unpacked = data.unpack(pack_str) #.last.unpack("l f8")
    p unpacked
    
    # override throttle control
    dataref = "sim/operation/override/override_throttles"
    d = dataref.unpack("C*")
    (500 - d.size).times do |i|
      dataref << "\000"
    end
    datagram = ["DREF", 0,1.0,dataref.unpack("C*")].flatten.pack("a4 C f C*")
    send_datagram datagram, '127.0.0.1', 49000


    # set my own throttle override
    dataref = "sim/flightmodel/engine/ENGN_thro_override"
    d = dataref.unpack("C*")
    (500 - d.size).times do |i|
      dataref << "\000"
    end
    datagram = ["DREF", 0,0.5,dataref.unpack("C*")].flatten.pack("a4 C f C*")
    send_datagram datagram, '127.0.0.1', 49000
    
    # try to get a dump the throttle override
    #dataref = "sim/network/dataout/data_to_internet"
    #d = dataref.unpack("C*")
    #(301 - d.size).times do |i|
    #  dataref << "\000"
    #end
    #c = "sim/flightmodel/engine/ENGN_thro_override"
    #(200 - c.size).times do |i|
    #  c << "\000"
    #end
    #c.unpack("C*")
    #datagram = ["DREF", 0,c.unpack("C*"),dataref.unpack("C*")].flatten.pack("a4 C200 f C*")
    #send_datagram datagram, '127.0.0.1', 49000
    
    
  end
  
end

EM.run {

  EM.open_datagram_socket('127.0.0.1', 48000, XplaneServer)

}