Packages

grisp

2.0.0
2.10.0 2.9.0 2.8.0 2.7.0 2.6.0 2.5.0 2.4.0 2.3.0 2.2.0 2.1.0 2.0.0 2.0.0-rc1 1.2.1 1.2.0 1.1.6 1.1.4 1.1.3 1.1.2 1.1.1 1.1.0 1.0.1 1.0.0 0.1.1 0.1.0

GRiSP Erlang Runtime Library

HexDocs

Current section

Files

Jump to
Readme
24 Versions
1 Dependency
3 Dependants
Files
Activity
grisp src grisp_nmea.erl
Raw

src/grisp_nmea.erl 

-module(grisp_nmea).



%--- Exports -------------------------------------------------------------------



-export([parse/1]).





%--- Types ---------------------------------------------------------------------



-type talker_id() :: 'gps' | 'glonass' | 'galileo' | 'beidou' | 'any' | binary().

-type message_id() :: 'dtm' | 'gbq' | 'gbs' | 'gga' | 'gll' | 'glq' | 'gnq'

                    | 'gns' | 'gpq' | 'grs' | 'gsa' | 'gst' | 'gsv' | 'rmc'

                    | 'txt' | 'vlw' | 'vtg' | 'zda' | binary().



-export_type([talker_id/0, message_id/0]).





%--- API Functions -------------------------------------------------------------



-spec parse(binary()) ->

    {ok, {talker_id(), message_id(), map() | binary()}} | {error, term()}.

parse(<<$$, Body/binary>>) ->

    case binary:split(Body, <<"*">>) of

        [Msg, HexCrc] ->

            nmea_parse_packet(Msg, HexCrc);

        _ ->

            {error, bad_format}

    end;

parse(_Bad) ->

    {error, bad_format}.





%--- Internal Functions --------------------------------------------------------



nmea_parse_packet(Body, Crc) ->

    try

        ExpectedCrc = nmea_crc(Body),

        case parse_crc(Crc) of

            ExpectedCrc ->

                case binary:split(Body, <<",">>) of

                    [Address, ValueData] ->

                        nmea_parse_address(Address, ValueData);

                    _ ->

                        {error, bad_format}

                end;

            _ ->

                {error, bad_crc}

        end

    catch

        bad_format ->

            {error, bad_format}

    end.



nmea_crc(Data) ->

    nmea_crc(Data, 0).



nmea_crc(<<>>, Acc) -> Acc;

nmea_crc(<<C:8, Rest/binary>>, Acc) ->

    nmea_crc(Rest, Acc bxor C).



nmea_split(Data, ExpectedSize) ->

    Fields = binary:split(Data, <<",">>, [global]),

    case length(Fields) =:= ExpectedSize of

        false -> erlang:throw(bad_format);

        true -> Fields

    end.



nmea_parse_address(<<T:2/binary, M/binary>>, ValueData) ->

    Talker = nmea_parse_talker_id(T),

    Type = nmea_parse_message_id(M),

    ParsedValues = nmea_parse_values(Talker, Type, ValueData),

    {ok, {Talker, Type, ParsedValues}}.



nmea_parse_values(_Talker, gga, Data) -> nmea_parse_gga(Data);

nmea_parse_values(_Talker, _Type, Data) -> Data.



nmea_parse_gga(Data) ->

    [T, Lat, NS, Long, EW, Q, _, _, Alt, AltU | _] = nmea_split(Data, 14),

    #{

        fixed => nmea_parse_gga_quality(Q),

        time => nmea_parse_time(T),

        lat => nmea_apply_direction(NS, nmea_parse_coordinate(Lat)),

        long => nmea_apply_direction(EW, nmea_parse_coordinate(Long)),

        alt => nmea_parse_altitude(Alt, AltU)

    }.



nmea_parse_time(<<>>) -> undefined;

nmea_parse_time(<<H:2/binary, M:2/binary, S:2/binary, $., X/binary>>) ->

    ((parse_dec(H, 2) * 60 + parse_dec(M, 2)) * 60 + parse_dec(S, 2)) * 1000 + parse_dec(X, 3);

nmea_parse_time(<<H:2/binary, M:2/binary, S:2/binary>>) ->

    ((parse_dec(H, 2) * 60 + parse_dec(M, 2)) * 60 + parse_dec(S, 2)) * 1000;

nmea_parse_time(_) ->

    erlang:throw(bad_format).



nmea_parse_coordinate(<<>>) -> undefined;

nmea_parse_coordinate(<<D:2/binary, M:2/binary, $., X/binary>>) ->

    ((parse_dec(D, 2) * 60 + parse_dec(M, 2)) * 1000000 + parse_dec(X, 6)) / (60 * 1000000);

nmea_parse_coordinate(<<D:3/binary, M:2/binary, $., X/binary>>) ->

    ((parse_dec(D, 3) * 60 + parse_dec(M, 2)) * 1000000 + parse_dec(X, 6)) / (60 * 1000000);

nmea_parse_coordinate(_) ->

    erlang:throw(bad_format).



nmea_parse_altitude(<<>>, _) -> undefined;

nmea_parse_altitude(Num, <<"M">>) ->

    parse_num(Num);

nmea_parse_altitude(_, _) ->

    erlang:throw(bad_format).



nmea_parse_gga_quality(<<>>)    -> false;

nmea_parse_gga_quality(<<"0">>) -> false;

nmea_parse_gga_quality(<<"1">>) -> true;

nmea_parse_gga_quality(<<"2">>) -> true;

nmea_parse_gga_quality(<<"4">>) -> true;

nmea_parse_gga_quality(<<"5">>) -> true;

nmea_parse_gga_quality(<<"6">>) -> false;

nmea_parse_gga_quality(_) ->

    erlang:throw(bad_format).



nmea_apply_direction(_, undefined) -> undefined;

nmea_apply_direction(<<"N">>, Coordinate) -> Coordinate;

nmea_apply_direction(<<"S">>, Coordinate) -> -Coordinate;

nmea_apply_direction(<<"E">>, Coordinate) -> Coordinate;

nmea_apply_direction(<<"W">>, Coordinate) -> -Coordinate;

nmea_apply_direction(_, _) ->

    erlang:throw(bad_format).



nmea_parse_talker_id(<<"GP">>) -> gps;

nmea_parse_talker_id(<<"GL">>) -> glonass;

nmea_parse_talker_id(<<"GA">>) -> galileo;

nmea_parse_talker_id(<<"GB">>) -> beidou;

nmea_parse_talker_id(<<"GN">>) -> any;

nmea_parse_talker_id(Other) when is_binary(Other) -> Other.



nmea_parse_message_id(<<"DTM">>) -> dtm;

nmea_parse_message_id(<<"GBQ">>) -> gbq;

nmea_parse_message_id(<<"GBS">>) -> gbs;

nmea_parse_message_id(<<"GGA">>) -> gga;

nmea_parse_message_id(<<"GLL">>) -> gll;

nmea_parse_message_id(<<"GLQ">>) -> glq;

nmea_parse_message_id(<<"GNQ">>) -> gnq;

nmea_parse_message_id(<<"GNS">>) -> gns;

nmea_parse_message_id(<<"GPQ">>) -> gpq;

nmea_parse_message_id(<<"GRS">>) -> grs;

nmea_parse_message_id(<<"GSA">>) -> gsa;

nmea_parse_message_id(<<"GST">>) -> gst;

nmea_parse_message_id(<<"GSV">>) -> gsv;

nmea_parse_message_id(<<"RMC">>) -> rmc;

nmea_parse_message_id(<<"TXT">>) -> txt;

nmea_parse_message_id(<<"VLW">>) -> vlw;

nmea_parse_message_id(<<"VTG">>) -> vtg;

nmea_parse_message_id(<<"ZDA">>) -> zda;

nmea_parse_message_id(Other) when is_binary(Other) -> Other.





%--- GENERIC PARSING FUNCTIONS -------------------------------------------------



parse_crc(<<>>) -> erlang:throw(bad_format);

parse_crc(Bin) -> parse_crc(Bin, 0).



parse_crc(<<>>, Acc) -> Acc;

parse_crc(<<"\n">>, Acc) -> Acc;

parse_crc(<<V:8, Rest/binary>>, Acc) ->

    parse_crc(Rest, Acc * 16 + hex_to_int(V)).



parse_dec(<<>>, _Digits) -> erlang:throw(bad_format);

parse_dec(Bin, Digits) -> parse_dec(Bin, Digits, 0).



parse_dec(<<>>, 0, Acc) -> Acc;

parse_dec(<<>>, Digits, _Acc) when Digits < 0 ->

    erlang:throw(bad_format);

parse_dec(<<>>, Digits, Acc) ->

    parse_dec(<<>>, Digits - 1 , Acc * 10);

parse_dec(<<V:8, Rest/binary>>, Digits, Acc) ->

    parse_dec(Rest, Digits - 1, Acc * 10 + dec_to_int(V)).



parse_num(<<>>) -> erlang:throw(bad_format);

parse_num(<<"-", Rest/binary>>) -> -parse_num(Rest);

parse_num(Bin) -> parse_num(Bin, undefined, 0).



parse_num(<<>>, undefined, Acc) -> Acc;

parse_num(<<>>, 1, Acc) -> Acc;

parse_num(<<>>, Denom, Acc) -> Acc / Denom;

parse_num(<<".", Rest/binary>>, undefined, Acc) ->

    parse_num(Rest, 1, Acc);

parse_num(<<V:8, Rest/binary>>, undefined, Acc) ->

    parse_num(Rest, undefined, Acc * 10 + dec_to_int(V));

parse_num(<<V:8, Rest/binary>>, Denom, Acc) ->

    parse_num(Rest, Denom * 10, Acc * 10 + dec_to_int(V)).



hex_to_int($0) -> 0;

hex_to_int($1) -> 1;

hex_to_int($2) -> 2;

hex_to_int($3) -> 3;

hex_to_int($4) -> 4;

hex_to_int($5) -> 5;

hex_to_int($6) -> 6;

hex_to_int($7) -> 7;

hex_to_int($8) -> 8;

hex_to_int($9) -> 9;

hex_to_int($A) -> 10;

hex_to_int($B) -> 11;

hex_to_int($C) -> 12;

hex_to_int($D) -> 13;

hex_to_int($E) -> 14;

hex_to_int($F) -> 15;

hex_to_int(_) ->

    erlang:throw(bad_format).



dec_to_int($0) -> 0;

dec_to_int($1) -> 1;

dec_to_int($2) -> 2;

dec_to_int($3) -> 3;

dec_to_int($4) -> 4;

dec_to_int($5) -> 5;

dec_to_int($6) -> 6;

dec_to_int($7) -> 7;

dec_to_int($8) -> 8;

dec_to_int($9) -> 9;

dec_to_int(_) ->

    erlang:throw(bad_format).