436 lines
12 KiB
C++
436 lines
12 KiB
C++
// nmea.cxx -- NMEA protocol 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 - http://www.flightgear.org/~curt
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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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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//
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// $Id$
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <cstdlib>
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#include <cstring>
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#include <cstdio>
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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 <simgear/timing/sg_time.hxx>
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#include <FDM/flightProperties.hxx>
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#include <Main/fg_props.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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mLength(0),
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mNmeaMessages(NMEA::SET),
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// by default, expect 2 messages per iteration (input)
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mMaxReceiveLines(2),
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mBiDirectionalSupport(false), // protocol normally only supports input _or_ output
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mLineFeed("\n")
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{
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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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void FGNMEA::add_with_checksum(char *sentence, unsigned int buf_size) {
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unsigned int i;
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unsigned char sum = 0;
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for (i = 1; sentence[i] != 0; i++ ) {
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sum ^= sentence[i];
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}
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if (i + 6 < buf_size)
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snprintf( &sentence[i], 6, "*%02X%s", sum, mLineFeed);
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SG_LOG( SG_IO, SG_DEBUG, sentence );
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mNmeaSentence += sentence;
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}
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// generate NMEA message
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bool FGNMEA::gen_message()
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{
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char dir;
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int deg;
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double min;
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char nmea[256];
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SGTime *t = globals->get_time_params();
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char utc[10];
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snprintf( utc, sizeof(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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{
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double latd = mFdm.get_Latitude() * SGD_RADIANS_TO_DEGREES;
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if ( latd < 0.0 ) {
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latd = -latd;
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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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snprintf( lat, sizeof(lat), "%02d%07.4f,%c", abs(deg), min, dir);
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}
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char lon[20];
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{
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double lond = mFdm.get_Longitude() * SGD_RADIANS_TO_DEGREES;
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if ( lond < 0.0 ) {
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lond = -lond;
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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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snprintf( lon, sizeof(lon), "%03d%07.4f,%c", abs(deg), min, dir);
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}
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double vn = fgGetDouble( "/velocities/speed-north-fps" );
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double ve = fgGetDouble( "/velocities/speed-east-fps" );
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char speed[10];
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{
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double fps = sqrt( vn*vn + ve*ve );
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double mps = fps * SG_FEET_TO_METER;
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double kts = mps * SG_METER_TO_NM * 3600;
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snprintf( speed, sizeof(speed), "%.1f", kts );
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}
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char heading[10];
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{
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double hdg_true = atan2( ve, vn ) * SGD_RADIANS_TO_DEGREES;
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if ( hdg_true < 0 ) {
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hdg_true += 360.0;
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}
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snprintf( heading, sizeof(heading), "%.1f", hdg_true );
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}
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double altitude_ft = mFdm.get_Altitude();
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char date[16];
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{
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unsigned short tm_mday = t->getGmt()->tm_mday;
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unsigned short tm_mon = t->getGmt()->tm_mon + 1;
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unsigned short tm_year = t->getGmt()->tm_year % 100;
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snprintf(date, sizeof(date), "%02u%02u%02u", tm_mday, tm_mon, tm_year);
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}
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char magvar[10];
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{
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float magdeg = fgGetDouble( "/environment/magnetic-variation-deg" );
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if ( magdeg < 0.0 ) {
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magdeg = -magdeg;
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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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snprintf( magvar, sizeof(magvar), "%.1f,%c", magdeg, dir );
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}
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// RMC sentence
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if (mNmeaMessages & NMEA::GPRMC)
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{
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// $GPRMC,HHMMSS,A,DDMM.MMMM,N,DDDMM.MMMM,W,XXX.X,XXX.X,DDMMYY,XXX.X,E,A*XX
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snprintf( nmea, sizeof(nmea), "$GPRMC,%s,A,%s,%s,%s,%s,%s,%s,A",
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utc, lat, lon, speed, heading, date, magvar );
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add_with_checksum(nmea, 256);
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}
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// GGA sentence
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if (mNmeaMessages & NMEA::GPGGA)
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{
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// $GPGGA,HHMMSS,DDMM.MMMM,N,DDDMM.MMMM,W,1,NN,H.H,AAAA.A,M,GG.G,M,,*XX
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snprintf( nmea, sizeof(nmea), "$GPGGA,%s,%s,%s,1,08,0.9,%.1f,M,0.0,M,,",
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utc, lat, lon, altitude_ft * SG_FEET_TO_METER );
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add_with_checksum(nmea, 256);
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}
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// GSA sentence (totally faked)
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if (mNmeaMessages & NMEA::GPGSA)
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{
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snprintf( nmea, sizeof(nmea), "%s%s",
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"$GPGSA,A,3,01,02,03,,05,,07,,09,,11,12,0.9,0.9,2.0*38", mLineFeed );
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SG_LOG( SG_IO, SG_DEBUG, nmea );
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mNmeaSentence += nmea;
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}
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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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// $GPGGA,163227,3321.173,N,11039.855,W,1,,,3333,F,,,,*0F
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void FGNMEA::parse_line() {
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SG_LOG( SG_IO, SG_DEBUG, "parse nmea message" );
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if (mLength > FG_MAX_MSG_SIZE-1)
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mLength = FG_MAX_MSG_SIZE-1;
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SG_LOG( SG_IO, SG_DEBUG, "entire message = " << mBuf );
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// test leading character
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if (mBuf[0] != '$')
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{
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SG_LOG( SG_IO, SG_DEBUG, " invalid NMEA start character = " << mBuf[0]);
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return;
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}
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// get rid of checksum and "*" delimiter
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while ((mLength > 0)&&(mBuf[mLength]!='*'))
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{
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mLength--;
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}
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mBuf[mLength] = 0;
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// split string to tokens
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std::vector<std::string> tokens;
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for (unsigned int pos=1;pos < mLength;pos++)
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{
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const char* pCurrent = &mBuf[pos];
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while ((mBuf[pos]!=',')&&(pos<mLength))
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pos++;
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if (mBuf[pos]==',')
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mBuf[pos] = 0;
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tokens.push_back(pCurrent);
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}
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if (tokens.empty())
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return;
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if (tokens.size()>1)
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{
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for (unsigned int i=0;i<tokens.size();i++)
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{
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SG_LOG( SG_IO, SG_DEBUG, " NMEA token # " << i << ": " << tokens[i]);
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}
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parse_message(tokens);
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}
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}
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void FGNMEA::parse_message(const std::vector<std::string>& tokens)
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{
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double lon_deg, lon_min, lat_deg, lat_min;
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double lon, lat;
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// string::size_type begin = 0, end;
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if (tokens[0] == "GPRMC" ) {
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// $GPRMC,HHMMSS,A,DDMM.MMMM,N,DDDMM.MMMM,W,XXX.X,XXX.X,DDMMYY,XXX.X,E,A*XX
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if ( tokens.size()<9)
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return;
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// #1: time
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const string& utc = tokens[1];
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SG_LOG( SG_IO, SG_DEBUG, " utc = " << utc );
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// #2: junk
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SG_LOG( SG_IO, SG_DEBUG, " junk = " << tokens[2] );
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// #3: lat val
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lat_deg = std::stod(tokens[3].substr(0, 2));
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lat_min = std::stod(tokens[3].substr(2));
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lat = lat_deg + ( lat_min / 60.0 );
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// #4: lat dir
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if ( tokens[4] == "S" )
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lat *= -1;
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mFdm.set_Latitude( lat * SGD_DEGREES_TO_RADIANS );
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// #5: lon val
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lon_deg = std::stod(tokens[5].substr(0, 3));
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lon_min = std::stod(tokens[5].substr(3));
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lon = lon_deg + ( lon_min / 60.0 );
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// #6: lon dir
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if ( tokens[6] == "W" )
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lon *= -1;
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mFdm.set_Longitude( lon * SGD_DEGREES_TO_RADIANS );
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SG_LOG( SG_IO, SG_DEBUG, " lat = " << lat << ", lon = " << lon );
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#if 0
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double sl_radius, lat_geoc;
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sgGeodToGeoc( mFdm.get_Latitude(),
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mFdm.get_Altitude(),
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&sl_radius, &lat_geoc );
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mFdm.set_Geocentric_Position( lat_geoc,
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mFdm.get_Longitude(),
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sl_radius + mFdm.get_Altitude() );
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#endif
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// #7: speed
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double speed = std::stod(tokens[7]);
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mFdm.set_V_calibrated_kts( speed );
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// mFdm.set_V_ground_speed( speed );
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SG_LOG( SG_IO, SG_DEBUG, " speed = " << speed );
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// #8: heading
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double heading = std::stod(tokens[8]);
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mFdm.set_Euler_Angles( mFdm.get_Phi(),
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mFdm.get_Theta(),
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heading * SGD_DEGREES_TO_RADIANS );
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SG_LOG( SG_IO, SG_DEBUG, " heading = " << heading );
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} else
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if (tokens[0] == "GPGGA" ) {
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if ( tokens.size()<11)
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return;
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// #1: time
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const string& utc = tokens[1];
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SG_LOG( SG_IO, SG_DEBUG, " utc = " << utc );
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// #2: lat val
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lat_deg = std::stod(tokens[2].substr(0, 2));
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lat_min = std::stod(tokens[2].substr(2));
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lat = lat_deg + ( lat_min / 60.0 );
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// #3: lat dir
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if ( tokens[4] == "S" )
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lat *= -1;
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mFdm.set_Latitude( lat * SGD_DEGREES_TO_RADIANS );
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// #4: lon val
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lon_deg = std::stod(tokens[4].substr(0, 3));
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lon_min = std::stod(tokens[4].substr(3));
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lon = lon_deg + ( lon_min / 60.0 );
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// #5: lon dir
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if ( tokens[5] == "W" )
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lon *= -1;
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mFdm.set_Longitude( lon * SGD_DEGREES_TO_RADIANS );
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SG_LOG( SG_IO, SG_DEBUG, " lat = " << lat << ", lon = " << lon );
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// #6: junk
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SG_LOG( SG_IO, SG_DEBUG, " junk = " << tokens[6] );
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// #7: junk
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SG_LOG( SG_IO, SG_DEBUG, " junk = " << tokens[7] );
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// #8: junk
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SG_LOG( SG_IO, SG_DEBUG, " junk = " << tokens[8] );
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// #9: altitude
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double altitude = std::stod(tokens[9]);
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// #10: altitude unit
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const string& alt_units = tokens[10];
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if ( alt_units != "F" && alt_units != "f" ) {
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altitude *= SG_METER_TO_FEET;
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}
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mFdm.set_Altitude( altitude );
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SG_LOG( SG_IO, SG_DEBUG, " altitude = " << altitude );
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}
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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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// bidirectional support does not make sense for NMEA (and Garmin) protocols
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if ((get_direction() == SG_IO_BI)&&
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(!mBiDirectionalSupport))
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{
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SG_LOG( SG_IO, SG_ALERT, "NMEA protocol does not support bidirectional communication. "
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"Use 'in' or 'out' instead of 'bi'.");
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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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( get_direction() == SG_IO_BI))
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{
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// process output
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gen_message();
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if ((!mNmeaSentence.empty())&&
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(!io->write( mNmeaSentence.c_str(), mNmeaSentence.length() )))
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{
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SG_LOG( SG_IO, SG_WARN, "Error writing data." );
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}
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mNmeaSentence = "";
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}
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if (( get_direction() == SG_IO_IN )||
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( get_direction() == SG_IO_BI))
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{
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// process input lines (normally expecting 2 messages per cycle)
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for (unsigned int i=0;i<mMaxReceiveLines;i++)
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{
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if ( (mLength = io->readline( mBuf, FG_MAX_MSG_SIZE )) > 0 ) {
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parse_line();
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} else {
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SG_LOG( SG_IO, SG_WARN, "Error reading data." );
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}
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}
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}
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return true; // return value is unused
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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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return io->close();
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}
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