//

// This file is part of Dire Wolf, an amateur radio packet TNC.

//

// Copyright (C) 2013, 2014 John Langner, WB2OSZ

//

// This program is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 2 of the License, or

// (at your option) any later version.

//

// This program is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

// GNU General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with this program. If not, see <http://www.gnu.org/licenses/>.

//

/*------------------------------------------------------------------

*

* Module: dwgps.c

*

* Purpose: Interface to location data, i.e. GPS receiver.

*

* Description: Tracker beacons need to know the current location.

* At this time, I can't think of any other reason why

* we would need this information.

*

* For Linux, we use gpsd and libgps.

* This has the extra benefit that the system clock can

* be set from the GPS signal.

*

* Not yet implemented for Windows. Not sure how yet.

* The Windows location API is new in Windows 7.

* At the end of 2013, about 1/3 of Windows users are

* still using XP so that still needs to be supported.

*

* Reference:

*

*---------------------------------------------------------------*/

#if TEST

#define ENABLE_GPS 1

#endif

#include <stdio.h>

#include <unistd.h>

#include <stdlib.h>

#include <assert.h>

#include <string.h>

#include <errno.h>

#include <sys/time.h>

#if __WIN32__

#include <windows.h>

#else

#if ENABLE_GPS

#include <gps.h>

#if GPSD_API_MAJOR_VERSION != 5

#error libgps API version might be incompatible.

#endif

#endif

#endif

#include "direwolf.h"

#include "textcolor.h"

#include "dwgps.h"

/* Was init successful? */

static enum { INIT_NOT_YET, INIT_SUCCESS, INIT_FAILED } init_status = INIT_NOT_YET;

#if __WIN32__

#include <windows.h>

#else

#if ENABLE_GPS

static struct gps_data_t gpsdata;

#endif

#endif

/*-------------------------------------------------------------------

*

* Name: dwgps_init

*

* Purpose: Intialize the GPS interface.

*

* Inputs: none.

*

* Returns: 0 = success

* -1 = failure

*

* Description: For Linux, this maps into gps_open.

* Not yet implemented for Windows.

*

*--------------------------------------------------------------------*/

int dwgps_init (void)

{

#if __WIN32__

/*

* Windows version. Not implemented yet.

*/

text_color_set(DW_COLOR_ERROR);

dw_printf ("GPS interface not yet available in Windows version.\n");

init_status = INIT_FAILED;

return (-1);

#elif ENABLE_GPS

int err;

#if USE_GPS_SHM

/*

* Linux - Shared memory interface to gpsd.

*

* I wanted to use this method because it is simpler and more efficient.

*

* The current version of gpsd, supplied with Raspian, is 3.6 from back in

* May 2012, is missing support for the shared memory interface.

* https://github.com/raspberrypi/linux/issues/523

*

* I tried to download a newer source and build with shared memory support

* but ran into a couple other issues.

*

* sudo apt-get install libncurses5-dev

* sudo apt-get install scons

* cd ~

* wget http://download-mirror.savannah.gnu.org/releases/gpsd/gpsd-3.11.tar.gz

* tar xfz gpsd-3.11.tar.gz

* cd gpsd-3.11

* scons prefix=/usr libdir=lib/arm-linux-gnueabihf shm_export=True python=False

* sudo scons udev-install

*

* For now, we will use the socket interface.

* Maybe get back to this again someday.

*/

err = gps_open (GPSD_SHARED_MEMORY, NULL, &gpsdata);

if (err != 0) {

text_color_set(DW_COLOR_ERROR);

dw_printf ("Unable to connect to GPSD shared memory interface, status=%d.\n", err);

if (err == NL_NOHOST) {

// I don't think this is right but we are not using it anyhow.

dw_printf ("Shared memory interface is not enabled in libgps.\n");

dw_printf ("Download the gpsd source and build with 'shm_export=True' option.\n");

}

else {

dw_printf ("%s\n", gps_errstr(errno));

}

init_status = INIT_FAILED;

return (-1);

}

init_status = INIT_SUCCESS;

return (0);

#else

/*

* Linux - Socket interface to gpsd.

*/

err = gps_open ("localhost", DEFAULT_GPSD_PORT, &gpsdata);

if (err != 0) {

text_color_set(DW_COLOR_ERROR);

dw_printf ("Unable to connect to GPSD stream, status%d.\n", err);

dw_printf ("%s\n", gps_errstr(errno));

init_status = INIT_FAILED;

return (-1);

}

gps_stream(&gpsdata, WATCH_ENABLE | WATCH_JSON, NULL);

init_status = INIT_SUCCESS;

return (0);

#endif

#else /* end ENABLE_GPS */

text_color_set(DW_COLOR_ERROR);

dw_printf ("GPS interface not enabled in this version.\n");

dw_printf ("See documentation on how to rebuild with ENABLE_GPS.\n");

init_status = INIT_FAILED;

return (-1);

#endif

} /* end dwgps_init */

/*-------------------------------------------------------------------

*

* Name: dwgps_read

*

* Purpose: Obtain current location from GPS receiver.

*

* Outputs: *plat - Latitude.

* *plon - Longitude.

* *pspeed - Speed, knots.

* *pcourse - Course over ground, degrees.

* *palt - Altitude, meters.

*

* Returns: -1 = error

* 0 = location currently not available (no fix)

* 2 = 2D fix, lat/lon, speed, and course are set.

* 3 - 3D fix, altitude is also set.

*

*--------------------------------------------------------------------*/

int dwgps_read (double *plat, double *plon, float *pspeed, float *pcourse, float *palt)

{

#if __WIN32__

text_color_set(DW_COLOR_ERROR);

dw_printf ("Internal error, dwgps_read, shouldn't be here.\n");

return (-1);

#elif ENABLE_GPS

int err;

if (init_status != INIT_SUCCESS) {

text_color_set(DW_COLOR_ERROR);

dw_printf ("Internal error, dwgps_read without successful init.\n");

return (-1);

}

#if USE_GPS_SHM

/*

* Shared memory version.

*/

err = gps_read (&gpsdata);

#if DEBUG

dw_printf ("gps_read returns %d bytes\n", err);

#endif

#else

/*

* Socket version.

*/

// Wait for up to 1000 milliseconds.

// This should only happen in the beaconing thread so

// I'm not worried about other functions hanging.

if (gps_waiting(&gpsdata, 1000)) {

err = gps_read (&gpsdata);

}

else {

gps_stream(&gpsdata, WATCH_ENABLE | WATCH_JSON, NULL);

sleep (1);

}

#endif

if (err > 0) {

/* Data is available. */

if (gpsdata.status >= STATUS_FIX && gpsdata.fix.mode >= MODE_2D) {

*plat = gpsdata.fix.latitude;

*plon = gpsdata.fix.longitude;

*pcourse = gpsdata.fix.track;

*pspeed = MPS_TO_KNOTS * gpsdata.fix.speed; /* libgps uses meters/sec */

if (gpsdata.fix.mode >= MODE_3D) {

*palt = gpsdata.fix.altitude;

return (3);

}

return (2);

}

/* No fix. Probably temporary condition. */

return (0);

}

else if (err == 0) {

/* No data available at the present time. */

return (0);

}

else {

/* More serious error. */

return (-1);

}

#else

text_color_set(DW_COLOR_ERROR);

dw_printf ("Internal error, dwgps_read, shouldn't be here.\n");

return (-1);

#endif

} /* end dwgps_read */

/*-------------------------------------------------------------------

*

* Name: dwgps_term

*

* Purpose: Shut down GPS interface before exiting from application.

*

* Inputs: none.

*

* Returns: none.

*

*--------------------------------------------------------------------*/

void dwgps_term (void) {

#if __WIN32__

#elif ENABLE_GPS

if (init_status == INIT_SUCCESS) {

#ifndef USE_GPS_SHM

gps_stream(&gpsdata, WATCH_DISABLE, NULL);

#endif

gps_close (&gpsdata);

}

#else

#endif

} /* end dwgps_term */

/*-------------------------------------------------------------------

*

* Name: main

*

* Purpose: Simple unit test for other functions in this file.

*

* Description: Compile with -DTEST option.

*

* gcc -DTEST dwgps.c textcolor.c -lgps

* ./a.out

*

*--------------------------------------------------------------------*/

#if TEST

int main (int argc, char *argv[])

{

#if __WIN32__

printf ("Not in win32 version yet.\n");

#elif ENABLE_GPS

int err;

int fix;

double lat;

double lon;

float speed;

float course;

float alt;

err = dwgps_init ();

if (err != 0) exit(1);

while (1) {

fix = dwgps_read (&lat, &lon, &speed, &course, &alt);

switch (fix) {

case 3:

case 2:

dw_printf ("%.6f %.6f", lat, lon);

dw_printf (" %.1f knots %.0f degrees", speed, course);

if (fix==3) dw_printf (" altitude = %.1f meters", alt);

dw_printf ("\n");

break;

case 0:

dw_printf ("location currently not available.\n");

break;

default:

dw_printf ("ERROR getting GPS information.\n");

}

sleep (3);

}

#else

printf ("Test: Shouldn't be here.\n");

#endif

} /* end main */

#endif

/* end dwgps.c */