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/*
* This provides the interface to the library that supports direct access to
* GPSes on serial or USB devices.
*/
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <netdb.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_FILIO_H
#include <sys/filio.h> /* for FIONREAD on BSD systems */
#endif
#include "gpsd.h"
struct gps_session_t *gpsd_init(char devicetype, char *dgpsserver)
/* initialize GPS polling */
{
time_t now = time(NULL);
struct gps_session_t *session = (struct gps_session_t *)calloc(sizeof(struct gps_session_t), 1);
if (!session)
return NULL;
session->gpsd_device = DEFAULT_DEVICE_NAME;
session->device_type = gpsd_drivers[0];
#ifdef NON_NMEA_ENABLE
{
struct gps_type_t **dp;
for (dp = gpsd_drivers; *dp; dp++)
if ((*dp)->typekey == devicetype) {
gpsd_report(3, "Selecting %s driver...\n", (*dp)->typename);
session->device_type = *dp;
goto foundit;
}
gpsd_report(1, "invalid GPS type \"%s\", using NMEA instead\n");
foundit:;
}
#endif /* NON_NMEA_ENABLE */
session->baudrate = session->device_type->baudrate;
session->dsock = -1;
if (dgpsserver) {
char hn[256], buf[BUFSIZE];
char *colon, *dgpsport = "rtcm-sc104";
if ((colon = strchr(dgpsserver, ':'))) {
dgpsport = colon+1;
*colon = '\0';
}
if (!getservbyname(dgpsport, "tcp"))
dgpsport = "2101";
session->dsock = netlib_connectsock(dgpsserver, dgpsport, "tcp");
if (session->dsock < 0)
gpsd_report(1, "Can't connect to dgps server, netlib error %d\n", session->dsock);
else {
gethostname(hn, sizeof(hn));
sprintf(buf, "HELO %s gpsd %s\r\nR\r\n", hn, VERSION);
write(session->dsock, buf, strlen(buf));
}
}
/* mark GPS fd closed */
session->gNMEAdata.gps_fd = -1;
INIT(session->gNMEAdata.online_stamp, now);
INIT(session->gNMEAdata.latlon_stamp, now);
INIT(session->gNMEAdata.altitude_stamp, now);
INIT(session->gNMEAdata.track_stamp, now);
INIT(session->gNMEAdata.speed_stamp, now);
INIT(session->gNMEAdata.status_stamp, now);
INIT(session->gNMEAdata.mode_stamp, now);
INIT(session->gNMEAdata.fix_quality_stamp, now);
INIT(session->gNMEAdata.satellite_stamp, now);
session->gNMEAdata.mode = MODE_NO_FIX;
return session;
}
void gpsd_deactivate(struct gps_session_t *session)
/* temporarily release the GPS device */
{
session->gNMEAdata.online = 0;
REFRESH(session->gNMEAdata.online_stamp);
session->gNMEAdata.mode = MODE_NO_FIX;
session->gNMEAdata.status = STATUS_NO_FIX;
gpsd_close(session);
session->gNMEAdata.gps_fd = -1;
if (session->device_type->wrapup)
session->device_type->wrapup(session);
gpsd_report(1, "closed GPS\n");
}
int gpsd_activate(struct gps_session_t *session)
/* acquire a connection to the GPS device */
{
if ((session->gNMEAdata.gps_fd = gpsd_open(session->baudrate, session->device_type->stopbits, session)) < 0)
return -1;
else {
session->gNMEAdata.online = 1;
REFRESH(session->gNMEAdata.online_stamp);
gpsd_report(1, "gpsd_activate: opened GPS (%d)\n", session->gNMEAdata.gps_fd);
/* if there is an initializer and no trigger string, invoke it */
if (session->device_type->initializer && !session->device_type->trigger)
session->device_type->initializer(session);
return session->gNMEAdata.gps_fd;
}
}
static int is_input_waiting(int fd)
{
int count;
if (fd < 0 || ioctl(fd, FIONREAD, &count) < 0)
return -1;
return count;
}
int gpsd_poll(struct gps_session_t *session)
/* update the stuff in the scoreboard structure */
{
int waiting;
/* accept a DGPS correction if one is pending */
if (is_input_waiting(session->dsock) > 0) {
char buf[BUFSIZE];
int rtcmbytes;
if ((rtcmbytes=read(session->dsock,buf,BUFSIZE))>0 && (session->gNMEAdata.gps_fd !=-1)) {
if (session->device_type->rtcm_writer(session, buf, rtcmbytes) <= 0)
gpsd_report(1, "Write to rtcm sink failed\n");
else
gpsd_report(2, "<= DGPS: %d bytes of RTCM relayed.\n", rtcmbytes);
} else
gpsd_report(1, "Read from rtcm source failed\n");
}
/* update the scoreboard structure from the GPS */
waiting = is_input_waiting(session->gNMEAdata.gps_fd);
gpsd_report(4, "GPS has %d chars waiting\n", waiting);
if (waiting < 0)
return waiting;
else if (!waiting) {
if (time(NULL) <= session->gNMEAdata.online_stamp.last_refresh + session->device_type->interval+1) {
return 0;
} else {
session->gNMEAdata.online = 0;
REFRESH(session->gNMEAdata.online_stamp);
return -1;
}
} else {
session->gNMEAdata.online = 1;
REFRESH(session->gNMEAdata.online_stamp);
/* call the input routine from the device-specific driver */
session->device_type->handle_input(session);
/* count the good fixes */
if (session->gNMEAdata.status > STATUS_NO_FIX)
session->fixcnt++;
/* may be time to ship a DGPS correction to the GPS */
if (session->fixcnt > 10 && !session->sentdgps) {
session->sentdgps++;
if (session->dsock > -1) {
char buf[BUFSIZE];
sprintf(buf, "R %0.8f %0.8f %0.2f\r\n",
session->gNMEAdata.latitude,
session->gNMEAdata.longitude,
session->gNMEAdata.altitude);
write(session->dsock, buf, strlen(buf));
gpsd_report(2, "=> dgps %s", buf);
}
}
}
return waiting;
}
void gpsd_wrap(struct gps_session_t *session)
/* end-of-session wrapup */
{
gpsd_deactivate(session);
if (session->dsock >= 0)
close(session->dsock);
}
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