//
// This file is part of Dire Wolf, an amateur radio packet TNC.
//
// Copyright (C) 2013, 2014, 2015, 2020 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: For Linux, we would normally want to use gpsd and libgps.
* This allows multiple applications to access the GPS data,
* without fighting over the same serial port, and has the
* extra benefit that the system clock can be set from the GPS signal.
*
* Reference: http://www.catb.org/gpsd/
*
*---------------------------------------------------------------*/
#include "direwolf.h"
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <errno.h>
#include <time.h>
#include <math.h>
#include <stddef.h>
#if __WIN32__
#error Not for Windows
#endif
#if ENABLE_GPSD
#include <gps.h>
// An incompatibility was introduced with version 7
// and again with 9 and again with 10.
#if GPSD_API_MAJOR_VERSION < 5 || GPSD_API_MAJOR_VERSION > 11
#error libgps API version might be incompatible.
#endif
/*
* Information for interface to gpsd daemon.
*/
static struct gps_data_t gpsdata;
#endif /* ENABLE_GPSD */
#include "textcolor.h"
#include "dwgps.h"
#include "dwgpsd.h"
#if ENABLE_GPSD
static int s_debug = 0; /* Enable debug output. */
/* >= 1 show results from dwgps_read. */
/* >= 2 show updates from GPS. */
static void * read_gpsd_thread (void *arg);
#endif
/*-------------------------------------------------------------------
*
* Name: dwgpsd_init
*
* Purpose: Initialize the GPS interface.
*
* Inputs: pconfig Configuration settings. This includes
* host name or address for network connection.
*
* debug - If >= 1, print results when dwgps_read is called.
* (In different file.)
*
* If >= 2, location updates are also printed.
* (In this file.)
*
* Returns: 1 = success
* 0 = nothing to do (no host specified in config)
* -1 = failure
*
* Description: - Establish socket connection with gpsd.
* - Start up thread to process incoming data.
* It reads from the daemon and deposits into
* shared region via dwgps_put_data.
*
* The application calls dwgps_read to get the most
* recent information.
*
*--------------------------------------------------------------------*/
/*
* Historical notes:
*
* Originally, I wanted to use the shared memory interface to gpsd
* because it is simpler and more efficient. Just access it when we
* actually need the data and we don't have a lot of extra unnecessary
* busy work going on constantly polling it when we don't need the information.
*
* The current version of gpsd, supplied with Raspian (Wheezy), is 3.6 from back in
* May 2012, is missing support for the shared memory interface.
*
* 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.
*
* Update: January 2016.
*
* I'm told that the shared memory interface might work in Raspian, Jessie version.
* Haven't tried it yet.
*
* June 2020: This is how to build the most recent.
*
* Based on https://www.satsignal.eu/raspberry-pi/UpdatingGPSD.html
*
* git clone https://gitlab.com/gpsd/gpsd.git gpsd-gitlab
* cd gpsd-gitlab
* scons --config=force
* scons
* sudo scons install
*
* The problem we have here is that the library is put in /usr/local/lib and direwolf
* can't find it there. Solution is to define environment variable:
*
* export LD_LIBRARY_PATH=/use/local/lib
*/
int dwgpsd_init (struct misc_config_s *pconfig, int debug)
{
#if ENABLE_GPSD
pthread_t read_gps_tid;
int e;
int err;
int arg = 0;
char sport[12];
s_debug = debug;
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dw_printf ("dwgpsd_init()\n");
}
/*
* Socket interface to gpsd.
*/
if (strlen(pconfig->gpsd_host) == 0) {
/* Nothing to do. Leave initial fix value of error. */
return (0);
}
snprintf (sport, sizeof(sport), "%d", pconfig->gpsd_port);
err = gps_open (pconfig->gpsd_host, sport, &gpsdata);
if (err != 0) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("Unable to connect to GPSD stream at %s:%s.\n", pconfig->gpsd_host, sport);
dw_printf ("%s\n", gps_errstr(errno));
return (-1);
}
gps_stream(&gpsdata, WATCH_ENABLE | WATCH_JSON, NULL);
e = pthread_create (&read_gps_tid, NULL, read_gpsd_thread, (void *)(ptrdiff_t)arg);
if (e != 0) {
text_color_set(DW_COLOR_ERROR);
perror("Could not create GPS reader thread");
return (-1);
}
/* success */
return (1);
#else /* end ENABLE_GPSD */
// Shouldn't be here.
text_color_set(DW_COLOR_ERROR);
dw_printf ("GPSD interface not enabled in this version.\n");
dw_printf ("See documentation on how to rebuild with ENABLE_GPSD.\n");
return (-1);
#endif
} /* end dwgps_init */
/*-------------------------------------------------------------------
*
* Name: read_gpsd_thread
*
* Purpose: Read information from GPSD, as it becomes available, and
* store in memory shared with dwgps_read.
*
* Inputs: arg - not used
*
*--------------------------------------------------------------------*/
#define TIMEOUT 15
#if ENABLE_GPSD
static void * read_gpsd_thread (void *arg)
{
dwgps_info_t info;
if (s_debug >= 1) {
text_color_set(DW_COLOR_DEBUG);
dw_printf ("starting read_gpsd_thread (%d)\n", (int)(long)arg);
}
dwgps_clear (&info);
info.fix = DWFIX_NOT_SEEN; /* clear not init state. */
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dwgps_print ("GPSD: ", &info);
}
dwgps_set_data (&info);
while (1) {
// Example code found here:
// https://lists.nongnu.org/archive/html/gpsd-dev/2017-11/msg00001.html
if ( ! gps_waiting(&gpsdata, TIMEOUT * 1000000)) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("------------------------------------------\n");
dw_printf ("dwgpsd: Timeout waiting for GPS data.\n");
dw_printf ("Is GPSD daemon running?\n");
dw_printf ("Troubleshooting tip: Try running cgps or xgps.\n");
dw_printf ("------------------------------------------\n");
info.fix = DWFIX_ERROR;
SLEEP_MS(5000);
continue;
}
// https://github.com/wb2osz/direwolf/issues/196
// https://bugzilla.redhat.com/show_bug.cgi?id=1674812
// gps_read has two new parameters in API version 7.
// It looks like this could be used to obtain the JSON message from the daemon.
// Specify NULL, instead of message buffer space, if this is not desired.
// Why couldn't they add a new function instead of introducing incompatibility?
#if GPSD_API_MAJOR_VERSION >= 7
if (gps_read (&gpsdata, NULL, 0) == -1) {
#else
if (gps_read (&gpsdata) == -1) {
#endif
text_color_set(DW_COLOR_ERROR);
dw_printf ("------------------------------------------\n");
dw_printf ("GPSD: Lost communication with gpsd server.\n");
dw_printf ("------------------------------------------\n");
info.fix = DWFIX_ERROR;
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dwgps_print ("GPSD: ", &info);
}
dwgps_set_data (&info);
break; // Jump out of loop and terminate thread.
}
#if GPSD_API_MAJOR_VERSION >= 9
// The gps.h revision history says:
// * mark altitude in gps_fix_t as deprecated and undefined
// This seems really stupid to me.
// If it is deprecated and undefined then take it out. Someone trying to use
// it would get a compile error and know that something needs to be done.
// Instead we all just go merrily on our way using a field that is [allegedly] undefined.
// Why not simply add more variables with different definitions of altitude
// and keep the original variable working as it always did?
// If it is truly undefined, as the comment would have us believe, numerous
// people will WASTE VAST AMOUNTS OF TIME pondering why altitude is now broken in
// their applications.
#define stupid_altitude altMSL
#else
#define stupid_altitude altitude
#endif
#if GPSD_API_MAJOR_VERSION >= 10
// They did it again. Whimsical incompatibilities that cause
// pain and aggravation for everyone trying to use this library.
//
// error: ‘struct gps_data_t’ has no member named ‘status’
//
// Yes, I can understand that it is a more logical place but it breaks
// all existing code that uses this.
// I'm really getting annoyed about wasting so much time on keeping up with all
// of these incompatibilities that are completely unnecessary.
#define stupid_status fix.status
#else
#define stupid_status status
#endif
if (s_debug >= 3) {
text_color_set(DW_COLOR_DEBUG);
dw_printf ("gpsdata: status=%d, mode=%d, lat=%.6f, lon=%.6f, track=%.1f, speed=%.1f, alt=%.0f\n",
gpsdata.stupid_status, gpsdata.fix.mode,
gpsdata.fix.latitude, gpsdata.fix.longitude,
gpsdata.fix.track, gpsdata.fix.speed, gpsdata.fix.stupid_altitude);
}
// Inform user about change in fix status.
switch (gpsdata.fix.mode) {
default:
case MODE_NOT_SEEN:
case MODE_NO_FIX:
if (info.fix >= DWFIX_2D) {
text_color_set(DW_COLOR_INFO);
dw_printf ("GPSD: Lost location fix.\n");
}
info.fix = DWFIX_NO_FIX;
break;
case MODE_2D:
if (info.fix != DWFIX_2D) {
text_color_set(DW_COLOR_INFO);
dw_printf ("GPSD: Location fix is now 2D.\n");
}
info.fix = DWFIX_2D;
break;
case MODE_3D:
if (info.fix != DWFIX_3D) {
text_color_set(DW_COLOR_INFO);
dw_printf ("GPSD: Location fix is now 3D.\n");
}
info.fix = DWFIX_3D;
break;
}
// Oct. 2020 - 'status' is always zero for latest version of libgps so we can't use that anymore.
if (/*gpsdata.stupid_status >= STATUS_FIX &&*/ gpsdata.fix.mode >= MODE_2D) {
info.dlat = isfinite(gpsdata.fix.latitude) ? gpsdata.fix.latitude : G_UNKNOWN;
info.dlon = isfinite(gpsdata.fix.longitude) ? gpsdata.fix.longitude : G_UNKNOWN;
// When stationary, track is NaN which is not finite.
info.track = isfinite(gpsdata.fix.track) ? gpsdata.fix.track : G_UNKNOWN;
info.speed_knots = isfinite(gpsdata.fix.speed) ? (MPS_TO_KNOTS * gpsdata.fix.speed) : G_UNKNOWN;
if (gpsdata.fix.mode >= MODE_3D) {
info.altitude = isfinite(gpsdata.fix.stupid_altitude) ? gpsdata.fix.stupid_altitude : G_UNKNOWN;
}
// Otherwise keep last known altitude when we downgrade from 3D to 2D fix.
// Caller knows altitude is outdated if info.fix == DWFIX_2D.
}
// Otherwise keep the last known location which is better than totally lost.
// Caller knows location is outdated if info.fix == DWFIX_NO_FIX.
info.timestamp = time(NULL);
if (s_debug >= 2) {
text_color_set(DW_COLOR_DEBUG);
dwgps_print ("GPSD: ", &info);
}
dwgps_set_data (&info);
}
return(0); // Terminate thread on serious error.
} /* end read_gpsd_thread */
#endif
/*-------------------------------------------------------------------
*
* Name: dwgpsd_term
*
* Purpose: Shut down GPS interface before exiting from application.
*
* Inputs: none.
*
* Returns: none.
*
*--------------------------------------------------------------------*/
void dwgpsd_term (void) {
#if ENABLE_GPSD
gps_stream (&gpsdata, WATCH_DISABLE, NULL);
gps_close (&gpsdata);
#endif
} /* end dwgpsd_term */
/*-------------------------------------------------------------------
*
* Name: main
*
* Purpose: Simple unit test for other functions in this file.
*
* Description: Compile with -DGPSTEST option.
*
* gcc -DGPSTEST -DENABLE_GPSD dwgpsd.c dwgps.c textcolor.o latlong.o misc.a -lm -lpthread -lgps
* ./a.out
*
*--------------------------------------------------------------------*/
#if GPSTEST
int dwgpsnmea_init (struct misc_config_s *pconfig, int debug)
{
return (0);
}
void dwgpsnmea_term (void)
{
return;
}
int main (int argc, char *argv[])
{
struct misc_config_s config;
dwgps_info_t info;
memset (&config, 0, sizeof(config));
strlcpy (config.gpsd_host, "localhost", sizeof(config.gpsd_host));
config.gpsd_port = atoi(DEFAULT_GPSD_PORT);
dwgps_init (&config, 3);
while (1) {
dwfix_t fix;
fix = dwgps_read (&info)
;
text_color_set (DW_COLOR_INFO);
switch (fix) {
case DWFIX_2D:
case DWFIX_3D:
dw_printf ("%.6f %.6f", info.dlat, info.dlon);
dw_printf (" %.1f knots %.0f degrees", info.speed_knots, info.track);
if (fix==3) dw_printf (" altitude = %.1f meters", info.altitude);
dw_printf ("\n");
break;
case DWFIX_NOT_SEEN:
case DWFIX_NO_FIX:
dw_printf ("Location currently not available.\n");
break;
case DWFIX_NOT_INIT:
dw_printf ("GPS Init failed.\n");
exit (1);
case DWFIX_ERROR:
default:
dw_printf ("ERROR getting GPS information.\n");
break;
}
SLEEP_SEC (3);
}
} /* end main */
#endif
/* end dwgpsd.c */