511 lines
12 KiB
C++
511 lines
12 KiB
C++
// nmea.cxx -- NMEA protocal class
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//
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// Written by Curtis Olson, started November 1999.
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//
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// Copyright (C) 1999 Curtis L. Olson - curt@flightgear.org
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as
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// published by the Free Software Foundation; either version 2 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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//
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// $Id$
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#include <simgear/debug/logstream.hxx>
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#include <simgear/math/sg_geodesy.hxx>
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#include <simgear/io/iochannel.hxx>
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#include <FDM/flight.hxx>
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#include <Main/globals.hxx>
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#include "nmea.hxx"
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FGNMEA::FGNMEA() {
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}
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FGNMEA::~FGNMEA() {
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}
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// calculate the nmea check sum
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static char calc_nmea_cksum(char *sentence) {
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unsigned char sum = 0;
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int i, len;
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// cout << sentence << endl;
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len = strlen(sentence);
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sum = sentence[0];
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for ( i = 1; i < len; i++ ) {
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// cout << sentence[i];
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sum ^= sentence[i];
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}
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// cout << endl;
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// printf("sum = %02x\n", sum);
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return sum;
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}
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// generate NMEA message
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bool FGNMEA::gen_message() {
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// cout << "generating nmea message" << endl;
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char rmc[256], gga[256];
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char rmc_sum[10], gga_sum[10];
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char dir;
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int deg;
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double min;
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SGTime *t = globals->get_time_params();
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char utc[10];
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sprintf( utc, "%02d%02d%02d",
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t->getGmt()->tm_hour, t->getGmt()->tm_min, t->getGmt()->tm_sec );
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char lat[20];
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double latd = cur_fdm_state->get_Latitude() * SGD_RADIANS_TO_DEGREES;
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if ( latd < 0.0 ) {
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latd *= -1.0;
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dir = 'S';
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} else {
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dir = 'N';
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}
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deg = (int)(latd);
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min = (latd - (double)deg) * 60.0;
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sprintf( lat, "%02d%06.3f,%c", abs(deg), min, dir);
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char lon[20];
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double lond = cur_fdm_state->get_Longitude() * SGD_RADIANS_TO_DEGREES;
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if ( lond < 0.0 ) {
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lond *= -1.0;
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dir = 'W';
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} else {
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dir = 'E';
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}
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deg = (int)(lond);
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min = (lond - (double)deg) * 60.0;
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sprintf( lon, "%03d%06.3f,%c", abs(deg), min, dir);
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char speed[10];
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sprintf( speed, "%05.1f", cur_fdm_state->get_V_equiv_kts() );
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char heading[10];
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sprintf( heading, "%05.1f", cur_fdm_state->get_Psi() * SGD_RADIANS_TO_DEGREES );
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char altitude_m[10];
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sprintf( altitude_m, "%02d",
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(int)(cur_fdm_state->get_Altitude() * SG_FEET_TO_METER) );
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char altitude_ft[10];
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sprintf( altitude_ft, "%02d", (int)cur_fdm_state->get_Altitude() );
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char date[10];
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sprintf( date, "%02d%02d%02d", t->getGmt()->tm_mday,
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t->getGmt()->tm_mon+1, t->getGmt()->tm_year );
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// $GPRMC,HHMMSS,A,DDMM.MMM,N,DDDMM.MMM,W,XXX.X,XXX.X,DDMMYY,XXX.X,E*XX
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sprintf( rmc, "GPRMC,%s,A,%s,%s,%s,%s,%s,0.000,E",
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utc, lat, lon, speed, heading, date );
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sprintf( rmc_sum, "%02X", calc_nmea_cksum(rmc) );
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sprintf( gga, "GPGGA,%s,%s,%s,1,,,%s,F,,,,",
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utc, lat, lon, altitude_ft );
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sprintf( gga_sum, "%02X", calc_nmea_cksum(gga) );
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SG_LOG( SG_IO, SG_DEBUG, rmc );
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SG_LOG( SG_IO, SG_DEBUG, gga );
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string nmea_sentence;
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// RMC sentence
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nmea_sentence = "$";
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nmea_sentence += rmc;
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nmea_sentence += "*";
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nmea_sentence += rmc_sum;
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nmea_sentence += "\n";
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// GGA sentence
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nmea_sentence += "$";
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nmea_sentence += gga;
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nmea_sentence += "*";
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nmea_sentence += gga_sum;
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nmea_sentence += "\n";
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cout << nmea_sentence;
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length = nmea_sentence.length();
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strncpy( buf, nmea_sentence.c_str(), length );
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return true;
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}
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// parse NMEA message. messages will look something like the
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// following:
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//
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// $GPRMC,163227,A,3321.173,N,11039.855,W,000.1,270.0,171199,0.000,E*61
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// $GPGGA,163227,3321.173,N,11039.855,W,1,,,3333,F,,,,*0F
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bool FGNMEA::parse_message() {
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SG_LOG( SG_IO, SG_INFO, "parse nmea message" );
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string msg = buf;
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msg = msg.substr( 0, length );
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SG_LOG( SG_IO, SG_INFO, "entire message = " << msg );
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string::size_type begin_line, end_line, begin, end;
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begin_line = begin = 0;
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// extract out each line
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end_line = msg.find("\n", begin_line);
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while ( end_line != string::npos ) {
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string line = msg.substr(begin_line, end_line - begin_line);
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begin_line = end_line + 1;
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SG_LOG( SG_IO, SG_INFO, " input line = " << line );
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// leading character
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string start = msg.substr(begin, 1);
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++begin;
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SG_LOG( SG_IO, SG_INFO, " start = " << start );
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// sentence
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string sentence = msg.substr(begin, end - begin);
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begin = end + 1;
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SG_LOG( SG_IO, SG_INFO, " sentence = " << sentence );
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double lon_deg, lon_min, lat_deg, lat_min;
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double lon, lat, speed, heading, altitude;
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if ( sentence == "GPRMC" ) {
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// time
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string utc = msg.substr(begin, end - begin);
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begin = end + 1;
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SG_LOG( SG_IO, SG_INFO, " utc = " << utc );
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// junk
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string junk = msg.substr(begin, end - begin);
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begin = end + 1;
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SG_LOG( SG_IO, SG_INFO, " junk = " << junk );
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// lat val
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string lat_str = msg.substr(begin, end - begin);
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begin = end + 1;
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lat_deg = atof( lat_str.substr(0, 2).c_str() );
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lat_min = atof( lat_str.substr(2).c_str() );
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// lat dir
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string lat_dir = msg.substr(begin, end - begin);
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begin = end + 1;
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lat = lat_deg + ( lat_min / 60.0 );
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if ( lat_dir == "S" ) {
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lat *= -1;
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}
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cur_fdm_state->set_Latitude( lat * SGD_DEGREES_TO_RADIANS );
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SG_LOG( SG_IO, SG_INFO, " lat = " << lat );
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// lon val
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string lon_str = msg.substr(begin, end - begin);
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begin = end + 1;
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lon_deg = atof( lon_str.substr(0, 3).c_str() );
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lon_min = atof( lon_str.substr(3).c_str() );
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// lon dir
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string lon_dir = msg.substr(begin, end - begin);
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begin = end + 1;
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lon = lon_deg + ( lon_min / 60.0 );
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if ( lon_dir == "W" ) {
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lon *= -1;
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}
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cur_fdm_state->set_Longitude( lon * SGD_DEGREES_TO_RADIANS );
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SG_LOG( SG_IO, SG_INFO, " lon = " << lon );
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#if 0
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double sl_radius, lat_geoc;
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sgGeodToGeoc( cur_fdm_state->get_Latitude(),
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cur_fdm_state->get_Altitude(),
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&sl_radius, &lat_geoc );
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cur_fdm_state->set_Geocentric_Position( lat_geoc,
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cur_fdm_state->get_Longitude(),
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sl_radius + cur_fdm_state->get_Altitude() );
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#endif
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// speed
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string speed_str = msg.substr(begin, end - begin);
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begin = end + 1;
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speed = atof( speed_str.c_str() );
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cur_fdm_state->set_V_calibrated_kts( speed );
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// cur_fdm_state->set_V_ground_speed( speed );
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SG_LOG( SG_IO, SG_INFO, " speed = " << speed );
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// heading
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string hdg_str = msg.substr(begin, end - begin);
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begin = end + 1;
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heading = atof( hdg_str.c_str() );
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cur_fdm_state->set_Euler_Angles( cur_fdm_state->get_Phi(),
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cur_fdm_state->get_Theta(),
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heading * SGD_DEGREES_TO_RADIANS );
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SG_LOG( SG_IO, SG_INFO, " heading = " << heading );
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} else if ( sentence == "GPGGA" ) {
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// time
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string utc = msg.substr(begin, end - begin);
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begin = end + 1;
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SG_LOG( SG_IO, SG_INFO, " utc = " << utc );
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// lat val
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string lat_str = msg.substr(begin, end - begin);
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begin = end + 1;
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lat_deg = atof( lat_str.substr(0, 2).c_str() );
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lat_min = atof( lat_str.substr(2).c_str() );
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// lat dir
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string lat_dir = msg.substr(begin, end - begin);
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begin = end + 1;
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lat = lat_deg + ( lat_min / 60.0 );
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if ( lat_dir == "S" ) {
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lat *= -1;
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}
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// cur_fdm_state->set_Latitude( lat * SGD_DEGREES_TO_RADIANS );
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SG_LOG( SG_IO, SG_INFO, " lat = " << lat );
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// lon val
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string lon_str = msg.substr(begin, end - begin);
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begin = end + 1;
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lon_deg = atof( lon_str.substr(0, 3).c_str() );
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lon_min = atof( lon_str.substr(3).c_str() );
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// lon dir
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string lon_dir = msg.substr(begin, end - begin);
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begin = end + 1;
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lon = lon_deg + ( lon_min / 60.0 );
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if ( lon_dir == "W" ) {
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lon *= -1;
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}
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// cur_fdm_state->set_Longitude( lon * SGD_DEGREES_TO_RADIANS );
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SG_LOG( SG_IO, SG_INFO, " lon = " << lon );
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// junk
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string junk = msg.substr(begin, end - begin);
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begin = end + 1;
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SG_LOG( SG_IO, SG_INFO, " junk = " << junk );
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// junk
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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junk = msg.substr(begin, end - begin);
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begin = end + 1;
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SG_LOG( SG_IO, SG_INFO, " junk = " << junk );
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// junk
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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junk = msg.substr(begin, end - begin);
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begin = end + 1;
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SG_LOG( SG_IO, SG_INFO, " junk = " << junk );
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// altitude
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string alt_str = msg.substr(begin, end - begin);
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altitude = atof( alt_str.c_str() );
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begin = end + 1;
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// altitude units
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end = msg.find(",", begin);
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if ( end == string::npos ) {
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return false;
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}
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string alt_units = msg.substr(begin, end - begin);
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begin = end + 1;
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if ( alt_units != (string)"F" ) {
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altitude *= SG_METER_TO_FEET;
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}
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cur_fdm_state->set_Altitude( altitude );
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SG_LOG( SG_IO, SG_INFO, " altitude = " << altitude );
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}
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// printf("%.8f %.8f\n", lon, lat);
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begin = begin_line;
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end_line = msg.find("\n", begin_line);
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}
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return true;
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}
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// open hailing frequencies
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bool FGNMEA::open() {
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if ( is_enabled() ) {
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SG_LOG( SG_IO, SG_ALERT, "This shouldn't happen, but the channel "
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<< "is already in use, ignoring" );
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return false;
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}
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SGIOChannel *io = get_io_channel();
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if ( ! io->open( get_direction() ) ) {
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SG_LOG( SG_IO, SG_ALERT, "Error opening channel communication layer." );
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return false;
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}
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set_enabled( true );
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return true;
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}
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// process work for this port
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bool FGNMEA::process() {
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SGIOChannel *io = get_io_channel();
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if ( get_direction() == SG_IO_OUT ) {
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gen_message();
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if ( ! io->write( buf, length ) ) {
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SG_LOG( SG_IO, SG_ALERT, "Error writing data." );
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return false;
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}
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} else if ( get_direction() == SG_IO_IN ) {
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if ( (length = io->readline( buf, FG_MAX_MSG_SIZE )) > 0 ) {
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parse_message();
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} else {
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SG_LOG( SG_IO, SG_ALERT, "Error reading data." );
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return false;
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}
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if ( (length = io->readline( buf, FG_MAX_MSG_SIZE )) > 0 ) {
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parse_message();
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} else {
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SG_LOG( SG_IO, SG_ALERT, "Error reading data." );
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return false;
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}
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}
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return true;
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}
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// close the channel
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bool FGNMEA::close() {
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SGIOChannel *io = get_io_channel();
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set_enabled( false );
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if ( ! io->close() ) {
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return false;
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}
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return true;
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}
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