//
// 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 */