flightgear/src/Network/atlas.cxx

/*
 * SPDX-FileName: atlas.cxx
 * SPDX-FileComment: Atlas protocol class
 * SPDX-FileCopyrightText: Copyright (C) 1999  Curtis L. Olson - http://www.flightgear.org/~curt
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include <cstdio>
#include <cstdlib>
#include <cstring>

#include <simgear/debug/logstream.hxx>
#include <simgear/math/sg_geodesy.hxx>
#include <simgear/io/iochannel.hxx>
#include <simgear/timing/sg_time.hxx>

#include <FDM/flightProperties.hxx>
#include <Main/globals.hxx>
#include <Main/fg_props.hxx>
#include <Main/fg_init.hxx>

#include "atlas.hxx"


FGAtlas::FGAtlas() :
  length(0),
  fdm(new FlightProperties)
{
  _adf_freq        = fgGetNode("/instrumentation/adf/frequencies/selected-khz", true);
  _nav1_freq       = fgGetNode("/instrumentation/nav/frequencies/selected-mhz", true);
  _nav1_sel_radial = fgGetNode("/instrumentation/nav/radials/selected-deg", true);
  _nav2_freq       = fgGetNode("/instrumentation/nav[1]/frequencies/selected-mhz", true);
  _nav2_sel_radial = fgGetNode("/instrumentation/nav[1]/radials/selected-deg", true);
}

FGAtlas::~FGAtlas() {
  delete fdm;
}


// calculate the atlas check sum
static char calc_atlas_cksum(char *sentence) {
    unsigned char sum = 0;
    int i, len;

    // cout << sentence << endl;

    len = strlen(sentence);
    sum = sentence[0];
    for ( i = 1; i < len; i++ ) {
        // cout << sentence[i];
        sum ^= sentence[i];
    }
    // cout << endl;

    // printf("sum = %02x\n", sum);
    return sum;
}

// generate Atlas message
bool FGAtlas::gen_message() {
    // cout << "generating atlas message" << endl;
    char rmc[256], gga[256], patla[256];
    char rmc_sum[10], gga_sum[10], patla_sum[10];
    char dir;
    int deg;
    double min;

    SGTime *t = globals->get_time_params();

    char utc[10];
    snprintf( utc, sizeof(utc), "%02d%02d%02d", 
	     t->getGmt()->tm_hour, t->getGmt()->tm_min, t->getGmt()->tm_sec );

    char lat[20];
    double latd = fdm->get_Latitude() * SGD_RADIANS_TO_DEGREES;
    if ( latd < 0.0 ) {
	latd *= -1.0;
	dir = 'S';
    } else {
	dir = 'N';
    }
    deg = (int)(latd);
    min = (latd - (double)deg) * 60.0;
    snprintf( lat, sizeof(lat), "%02d%06.3f,%c", abs(deg), min, dir);

    char lon[20];
    double lond = fdm->get_Longitude() * SGD_RADIANS_TO_DEGREES;
    if ( lond < 0.0 ) {
	lond *= -1.0;
	dir = 'W';
    } else {
	dir = 'E';
    }
    deg = (int)(lond);
    min = (lond - (double)deg) * 60.0;
    snprintf( lon, sizeof(lon), "%03d%06.3f,%c", abs(deg), min, dir);

    char speed[10];
    snprintf( speed, sizeof(speed), "%05.1f", fdm->get_V_equiv_kts() );

    char heading[10];
    snprintf( heading, sizeof(heading), "%05.1f", fdm->get_Psi() * SGD_RADIANS_TO_DEGREES );

    char altitude_m[10];
    snprintf( altitude_m, sizeof(altitude_m), "%02d", 
	     (int)(fdm->get_Altitude() * SG_FEET_TO_METER) );

    char altitude_ft[10];
    snprintf( altitude_ft, sizeof(altitude_ft), "%02d", (int)fdm->get_Altitude() );

    char date[16];
	unsigned short tm_mday = t->getGmt()->tm_mday;
	unsigned short tm_mon = t->getGmt()->tm_mon + 1;
	unsigned short tm_year = t->getGmt()->tm_year;
    snprintf( date, sizeof(date), "%02u%02u%02u", tm_mday, tm_mon, tm_year);

    // $GPRMC,HHMMSS,A,DDMM.MMM,N,DDDMM.MMM,W,XXX.X,XXX.X,DDMMYY,XXX.X,E*XX
    snprintf( rmc, sizeof(rmc), "GPRMC,%s,A,%s,%s,%s,%s,%s,0.000,E",
	     utc, lat, lon, speed, heading, date );
    snprintf( rmc_sum, sizeof(rmc_sum), "%02X", calc_atlas_cksum(rmc) );

    snprintf( gga, sizeof(gga), "GPGGA,%s,%s,%s,1,,,%s,F,,,,",
	     utc, lat, lon, altitude_ft );
    snprintf( gga_sum, sizeof(gga_sum), "%02X", calc_atlas_cksum(gga) );

    snprintf( patla, sizeof(patla), "PATLA,%.2f,%.1f,%.2f,%.1f,%.0f",
             _nav1_freq->getDoubleValue(),
             _nav1_sel_radial->getDoubleValue(),
             _nav2_freq->getDoubleValue(),
             _nav2_sel_radial->getDoubleValue(),
             _adf_freq->getDoubleValue() );
    snprintf( patla_sum, sizeof(patla_sum), "%02X", calc_atlas_cksum(patla) );

    SG_LOG( SG_IO, SG_DEBUG, rmc );
    SG_LOG( SG_IO, SG_DEBUG, gga );
    SG_LOG( SG_IO, SG_DEBUG, patla );

    std::string atlas_sentence;

    // RMC sentence
    atlas_sentence = "$";
    atlas_sentence += rmc;
    atlas_sentence += "*";
    atlas_sentence += rmc_sum;
    atlas_sentence += "\n";

    // GGA sentence
    atlas_sentence += "$";
    atlas_sentence += gga;
    atlas_sentence += "*";
    atlas_sentence += gga_sum;
    atlas_sentence += "\n";

    // PATLA sentence
    atlas_sentence += "$";
    atlas_sentence += patla;
    atlas_sentence += "*";
    atlas_sentence += patla_sum;
    atlas_sentence += "\n";

    //    cout << atlas_sentence;

    length = atlas_sentence.length();
    strncpy( buf, atlas_sentence.c_str(), length );

    return true;
}


// parse Atlas message.  messages will look something like the
// following:
//
// $GPRMC,163227,A,3321.173,N,11039.855,W,000.1,270.0,171199,0.000,E*61
// $GPGGA,163227,3321.173,N,11039.855,W,1,,,3333,F,,,,*0F

bool FGAtlas::parse_message() {
    SG_LOG( SG_IO, SG_INFO, "parse atlas message" );

    std::string msg = buf;
    msg = msg.substr( 0, length );
    SG_LOG( SG_IO, SG_INFO, "entire message = " << msg );

    std::string::size_type begin_line, end_line, begin, end;
    begin_line = begin = 0;

    // extract out each line
    end_line = msg.find("\n", begin_line);
    while ( end_line != std::string::npos ) {
	std::string line = msg.substr(begin_line, end_line - begin_line);
	begin_line = end_line + 1;
	SG_LOG( SG_IO, SG_INFO, "  input line = " << line );

	// leading character
	std::string start = msg.substr(begin, 1);
	++begin;
	SG_LOG( SG_IO, SG_INFO, "  start = " << start );

	// sentence
	end = msg.find(",", begin);
	if ( end == std::string::npos ) {
	    return false;
	}
    
	std::string sentence = msg.substr(begin, end - begin);
	begin = end + 1;
	SG_LOG( SG_IO, SG_INFO, "  sentence = " << sentence );

	double lon_deg, lon_min, lat_deg, lat_min;
	double lon, lat, speed, heading, altitude;

	if ( sentence == "GPRMC" ) {
	    // time
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string utc = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  utc = " << utc );

	    // junk
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string junk = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  junk = " << junk );

	    // lat val
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string lat_str = msg.substr(begin, end - begin);
	    begin = end + 1;

	    lat_deg = atof( lat_str.substr(0, 2).c_str() );
	    lat_min = atof( lat_str.substr(2).c_str() );

	    // lat dir
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string lat_dir = msg.substr(begin, end - begin);
	    begin = end + 1;

	    lat = lat_deg + ( lat_min / 60.0 );
	    if ( lat_dir == "S" ) {
		lat *= -1;
	    }

	    fdm->set_Latitude( lat * SGD_DEGREES_TO_RADIANS );
	    SG_LOG( SG_IO, SG_INFO, "  lat = " << lat );

	    // lon val
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string lon_str = msg.substr(begin, end - begin);
	    begin = end + 1;

	    lon_deg = atof( lon_str.substr(0, 3).c_str() );
	    lon_min = atof( lon_str.substr(3).c_str() );

	    // lon dir
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string lon_dir = msg.substr(begin, end - begin);
	    begin = end + 1;

	    lon = lon_deg + ( lon_min / 60.0 );
	    if ( lon_dir == "W" ) {
		lon *= -1;
	    }

	    fdm->set_Longitude( lon * SGD_DEGREES_TO_RADIANS );
	    SG_LOG( SG_IO, SG_INFO, "  lon = " << lon );

#if 0
	    double sl_radius, lat_geoc;
	    sgGeodToGeoc( fdm->get_Latitude(), 
			  fdm->get_Altitude(), 
			  &sl_radius, &lat_geoc );
	    fdm->set_Geocentric_Position( lat_geoc, 
			   fdm->get_Longitude(), 
	     	           sl_radius + fdm->get_Altitude() );
#endif

	    // speed
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string speed_str = msg.substr(begin, end - begin);
	    begin = end + 1;
	    speed = atof( speed_str.c_str() );
	    fdm->set_V_calibrated_kts( speed );
	    // fdm->set_V_ground_speed( speed );
	    SG_LOG( SG_IO, SG_INFO, "  speed = " << speed );

	    // heading
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string hdg_str = msg.substr(begin, end - begin);
	    begin = end + 1;
	    heading = atof( hdg_str.c_str() );
	    fdm->set_Euler_Angles( fdm->get_Phi(), 
					     fdm->get_Theta(), 
					     heading * SGD_DEGREES_TO_RADIANS );
	    SG_LOG( SG_IO, SG_INFO, "  heading = " << heading );
	} else if ( sentence == "GPGGA" ) {
	    // time
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string utc = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  utc = " << utc );

	    // lat val
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string lat_str = msg.substr(begin, end - begin);
	    begin = end + 1;

	    lat_deg = atof( lat_str.substr(0, 2).c_str() );
	    lat_min = atof( lat_str.substr(2).c_str() );

	    // lat dir
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string lat_dir = msg.substr(begin, end - begin);
	    begin = end + 1;

	    lat = lat_deg + ( lat_min / 60.0 );
	    if ( lat_dir == "S" ) {
		lat *= -1;
	    }

	    // fdm->set_Latitude( lat * SGD_DEGREES_TO_RADIANS );
	    SG_LOG( SG_IO, SG_INFO, "  lat = " << lat );

	    // lon val
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string lon_str = msg.substr(begin, end - begin);
	    begin = end + 1;

	    lon_deg = atof( lon_str.substr(0, 3).c_str() );
	    lon_min = atof( lon_str.substr(3).c_str() );

	    // lon dir
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string lon_dir = msg.substr(begin, end - begin);
	    begin = end + 1;

	    lon = lon_deg + ( lon_min / 60.0 );
	    if ( lon_dir == "W" ) {
		lon *= -1;
	    }

	    // fdm->set_Longitude( lon * SGD_DEGREES_TO_RADIANS );
	    SG_LOG( SG_IO, SG_INFO, "  lon = " << lon );

	    // junk
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string junk = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  junk = " << junk );

	    // junk
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    junk = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  junk = " << junk );

	    // junk
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    junk = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  junk = " << junk );

	    // altitude
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string alt_str = msg.substr(begin, end - begin);
	    altitude = atof( alt_str.c_str() );
	    begin = end + 1;

	    // altitude units
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string alt_units = msg.substr(begin, end - begin);
	    begin = end + 1;

	    if ( alt_units != "F" ) {
		altitude *= SG_METER_TO_FEET;
	    }

	    fdm->set_Altitude( altitude );
    
 	    SG_LOG( SG_IO, SG_INFO, " altitude  = " << altitude );

	} else if ( sentence == "PATLA" ) {
	    // nav1 freq
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string nav1_freq = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  nav1_freq = " << nav1_freq );

	    // nav1 selected radial
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string nav1_rad = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  nav1_rad = " << nav1_rad );

	    // nav2 freq
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string nav2_freq = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  nav2_freq = " << nav2_freq );

	    // nav2 selected radial
	    end = msg.find(",", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string nav2_rad = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  nav2_rad = " << nav2_rad );

	    // adf freq
	    end = msg.find("*", begin);
	    if ( end == std::string::npos ) {
		return false;
	    }
    
	    std::string adf_freq = msg.substr(begin, end - begin);
	    begin = end + 1;
	    SG_LOG( SG_IO, SG_INFO, "  adf_freq = " << adf_freq );
	}

	// printf("%.8f %.8f\n", lon, lat);

	begin = begin_line;
	end_line = msg.find("\n", begin_line);
    }

    return true;
}


// open hailing frequencies
bool FGAtlas::open() {
    if ( is_enabled() ) {
	SG_LOG( SG_IO, SG_ALERT, "This shouldn't happen, but the channel " 
		<< "is already in use, ignoring" );
	return false;
    }

    SGIOChannel *io = get_io_channel();

    if ( ! io->open( get_direction() ) ) {
	SG_LOG( SG_IO, SG_ALERT, "Error opening channel communication layer." );
	return false;
    }

    set_enabled( true );

    return true;
}


// process work for this port
bool FGAtlas::process() {
    SGIOChannel *io = get_io_channel();

    if ( get_direction() == SG_IO_OUT ) {
	gen_message();
	if ( ! io->write( buf, length ) ) {
	    SG_LOG( SG_IO, SG_WARN, "Error writing data." );
	    return false;
	}
    } else if ( get_direction() == SG_IO_IN ) {
	if ( (length = io->readline( buf, FG_MAX_MSG_SIZE )) > 0 ) {
	    parse_message();
	} else {
	    SG_LOG( SG_IO, SG_WARN, "Error reading data." );
	    return false;
	}
	if ( (length = io->readline( buf, FG_MAX_MSG_SIZE )) > 0 ) {
	    parse_message();
	} else {
	    SG_LOG( SG_IO, SG_WARN, "Error reading data." );
	    return false;
	}
    }

    return true;
}


// close the channel
bool FGAtlas::close() {
    SG_LOG( SG_IO, SG_INFO, "closing FGAtlas" );   
    SGIOChannel *io = get_io_channel();

    set_enabled( false );

    if ( ! io->close() ) {
	return false;
    }

    return true;
}