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driver_nmea0183.c
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/*
* This file is Copyright (c) 2010-2018 by the GPSD project
* SPDX-License-Identifier: BSD-2-clause
*/
/* for vsnprintf() FreeBSD wants __ISO_C_VISIBLE >= 1999 */
#define __ISO_C_VISIBLE 1999
#include "gpsd_config.h" /* must be before all includes */
#include <ctype.h> /* for isdigit() */
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <math.h>
#include <string.h>
#include <stdarg.h>
#include <time.h>
#include "gpsd.h"
#include "strfuncs.h"
#ifdef NMEA0183_ENABLE
/**************************************************************************
*
* Parser helpers begin here
*
**************************************************************************/
/* process a pair of latitude/longitude fields starting at field index BEGIN
* The input fields look like this:
* field[0]: 4404.1237962
* field[1]: N
* field[2]: 12118.8472460
* field[3]: W
* input format of lat/lon is NMEA style DDDMM.mmmmmmm
* yes, 7 digits of precision from survey grade GPS
*
* return: 0 == OK, non zero is failure.
*/
static int do_lat_lon(char *field[], struct gps_fix_t *out)
{
double d, m;
double lon;
double lat;
if ('\0' == field[0][0] ||
'\0' == field[1][0] ||
'\0' == field[2][0] ||
'\0' == field[3][0]) {
return 1;
}
lat = safe_atof(field[0]);
m = 100.0 * modf(lat / 100.0, &d);
lat = d + m / 60.0;
if ('S' == field[1][0])
lat = -lat;
lon = safe_atof(field[2]);
m = 100.0 * modf(lon / 100.0, &d);
lon = d + m / 60.0;
if ('W' == field[3][0])
lon = -lon;
if (0 == isfinite(lat) ||
0 == isfinite(lon)) {
return 2;
}
out->latitude = lat;
out->longitude = lon;
return 0;
}
/* process an FAA mode character
* return status as in session->gpsdata.status
*/
static int faa_mode(char mode)
{
int newstatus = STATUS_FIX;
switch (mode) {
case '\0': /* missing */
newstatus = STATUS_NO_FIX;
break;
case 'A': /* Autonomous */
default:
newstatus = STATUS_FIX;
break;
case 'D': /* Differential */
newstatus = STATUS_DGPS_FIX;
break;
case 'E': /* Estimated dead reckoning */
newstatus = STATUS_DR;
break;
case 'F': /* Float RTK */
newstatus = STATUS_RTK_FLT;
break;
case 'N': /* Data Not Valid */
/* already handled, for paranoia sake also here */
newstatus = STATUS_NO_FIX;
break;
case 'P': /* Precise (NMEA 4+) */
newstatus = STATUS_DGPS_FIX; /* sort of DGPS */
break;
case 'R': /* fixed RTK */
newstatus = STATUS_RTK_FIX;
break;
case 'S': /* simulator */
newstatus = STATUS_NO_FIX; /* or maybe MODE_FIX? */
break;
}
return newstatus;
}
/**************************************************************************
*
* Scary timestamp fudging begins here
*
* Four sentences, GGA and GLL and RMC and ZDA, contain timestamps.
* GGA/GLL/RMC timestamps look like hhmmss.ss, with the trailing .ss,
* or .sss, part optional.
* RMC has a date field, in the format ddmmyy. ZDA has separate fields
* for day/month/year, with a 4-digit year. This means that for RMC we
* must supply a century and for GGA and GLL we must supply a century,
* year, and day. We get the missing data from a previous RMC or ZDA;
* century in RMC is supplied from the daemon's context (initialized at
* startup time) if there has been no previous ZDA.
*
**************************************************************************/
#define DD(s) ((int)((s)[0]-'0')*10+(int)((s)[1]-'0'))
/* sentence supplied ddmmyy, but no century part
*
* return: 0 == OK, greater than zero on failure
*/
static int merge_ddmmyy(char *ddmmyy, struct gps_device_t *session)
{
int yy;
int mon;
int mday;
int year;
unsigned i; /* NetBSD complains about signed array index */
if (NULL == ddmmyy) {
return 1;
}
for (i = 0; i < 6; i++) {
/* NetBSD 6 wants the cast */
if (0 == isdigit((int)ddmmyy[i])) {
/* catches NUL and non-digits */
/* Telit HE910 can set year to "-1" (1999 - 2000) */
gpsd_log(&session->context->errout, LOG_WARN,
"merge_ddmmyy(%s), malformed date\n", ddmmyy);
return 2;
}
}
/* check for termination */
if ('\0' != ddmmyy[6]) {
/* missing NUL */
gpsd_log(&session->context->errout, LOG_WARN,
"merge_ddmmyy(%s), malformed date\n", ddmmyy);
return 3;
}
/* should be no defects left to segfault DD() */
yy = DD(ddmmyy + 4);
mon = DD(ddmmyy + 2);
mday = DD(ddmmyy);
/* check for century wrap */
if (session->nmea.date.tm_year % 100 == 99 && yy == 0)
gpsd_century_update(session, session->context->century + 100);
year = (session->context->century + yy);
/* 32 bit systems will break in 2038.
* Telix fails on GPS rollover to 2099, which 32 bit system
* can not handle. So wrap at 2080. That way 64 bit systems
* work until 2080, and 2099 gets reported as 1999.
* since GPS epoch started in 1980, allows for old NMEA to work.
*/
if (2080 <= year) {
year -= 100;
}
if ( (1 > mon ) || (12 < mon ) ) {
gpsd_log(&session->context->errout, LOG_WARN,
"merge_ddmmyy(%s), malformed month\n", ddmmyy);
return 4;
} else if ( (1 > mday ) || (31 < mday ) ) {
gpsd_log(&session->context->errout, LOG_WARN,
"merge_ddmmyy(%s), malformed day\n", ddmmyy);
return 5;
} else {
gpsd_log(&session->context->errout, LOG_DATA,
"merge_ddmmyy(%s) sets year %d\n",
ddmmyy, year);
session->nmea.date.tm_year = year - 1900;
session->nmea.date.tm_mon = mon - 1;
session->nmea.date.tm_mday = mday;
}
return 0;
}
/* update from a UTC time
*
* return: 0 == OK, greater than zero on failure
*/
static int merge_hhmmss(char *hhmmss, struct gps_device_t *session)
{
int old_hour = session->nmea.date.tm_hour;
int i, sublen;
if (NULL == hhmmss) {
return 1;
}
for (i = 0; i < 6; i++) {
/* NetBSD 6 wants the cast */
if (0 == isdigit((int)hhmmss[i])) {
/* catches NUL and non-digits */
gpsd_log(&session->context->errout, LOG_WARN,
"merge_hhmmss(%s), malformed time\n", hhmmss);
return 2;
}
}
/* don't check for termination, might have fractional seconds */
session->nmea.date.tm_hour = DD(hhmmss);
if (session->nmea.date.tm_hour < old_hour) /* midnight wrap */
session->nmea.date.tm_mday++;
session->nmea.date.tm_min = DD(hhmmss + 2);
session->nmea.date.tm_sec = DD(hhmmss + 4);
if ('.' == hhmmss[6] &&
/* NetBSD 6 wants the cast */
0 != isdigit((int)hhmmss[7])) {
i = atoi(hhmmss + 7);
sublen = strlen(hhmmss + 7);
session->nmea.subseconds = i / pow(10.0, sublen);
} else {
session->nmea.subseconds = 0.0;
}
return 0;
}
static void register_fractional_time(const char *tag, const char *fld,
struct gps_device_t *session)
{
if (fld[0] != '\0') {
session->nmea.last_frac_time = session->nmea.this_frac_time;
session->nmea.this_frac_time = safe_atof(fld);
session->nmea.latch_frac_time = true;
gpsd_log(&session->context->errout, LOG_DATA,
"%s: registers fractional time %.3f\n",
tag, session->nmea.this_frac_time);
}
}
/**************************************************************************
*
* Compare GPS timestamps for equality. Depends on the fact that the
* timestamp granularity of GPS is 1/100th of a second. Use this to avoid
* naive float comparisons.
*
* WARNING: many GPS now report time to .sss. 1/1000th. But so far
* no GPS reports fixes faster than 20Hz.
*
**************************************************************************/
#define GPS_TIME_EQUAL(a, b) (fabs((a) - (b)) < 0.01)
/**************************************************************************
*
* NMEA sentence handling begins here
*
**************************************************************************/
/* process xxVTG
* $GPVTG,054.7,T,034.4,M,005.5,N,010.2,K
* $GPVTG,054.7,T,034.4,M,005.5,N,010.2,K,A
*
* where:
* 1,2 054.7,T True track made good (degrees)
* 3,4 034.4,M Magnetic track made good
* 5,6 005.5,N Ground speed, knots
* 7,8 010.2,K Ground speed, Kilometers per hour
* 9 A Mode Indicator (optional)
* see faa_mode() for possible mode values
*
* see also:
* https://gpsd.gitlab.io/gpsd/NMEA.html#_vtg_track_made_good_and_ground_speed
*/
static gps_mask_t processVTG(int count,
char *field[],
struct gps_device_t *session)
{
gps_mask_t mask = ONLINE_SET;
if( (field[1][0] == '\0') || (field[5][0] == '\0')){
return mask;
}
/* ignore empty/missing field, fix mode of last resort */
if ((count > 9) && ('\0' != field[9][0])) {
switch (field[9][0]) {
case 'A':
/* Autonomous, 2D or 3D fix */
/* FALL THROUGH */
case 'D':
/* Differential, 2D or 3D fix */
// MODE_SET here causes issues
// mask |= MODE_SET;
break;
case 'E':
/* Estimated, DR only */
/* FALL THROUGH */
case 'N':
/* Not Valid */
// MODE_SET here causes issues
// mask |= MODE_SET;
// nothing to use here, leave
return mask;
default:
/* Huh? */
break;
}
}
// set true track
session->newdata.track = safe_atof(field[1]);
mask |= TRACK_SET;
// set magnetic variation
if (field[3][0] != '\0'){ // ignore empty fields
session->newdata.magnetic_track = safe_atof(field[3]);
mask |= MAGNETIC_TRACK_SET;
}
session->newdata.speed = safe_atof(field[5]) * KNOTS_TO_MPS;
mask |= SPEED_SET;
gpsd_log(&session->context->errout, LOG_DATA,
"VTG: course(T)=%.2f, course(M)=%.2f, speed=%.2f",
session->newdata.track, session->newdata.magnetic_track,
session->newdata.speed);
return mask;
}
/* Recommend Minimum Course Specific GPS/TRANSIT Data */
static gps_mask_t processRMC(int count, char *field[],
struct gps_device_t *session)
{
/*
* RMC,225446.33,A,4916.45,N,12311.12,W,000.5,054.7,191194,020.3,E,A*68
* 1 225446.33 Time of fix 22:54:46 UTC
* 2 A Status of Fix:
* A = Autonomous, valid;
* D = Differential, valid;
* V = invalid
* 3,4 4916.45,N Latitude 49 deg. 16.45 min North
* 5,6 12311.12,W Longitude 123 deg. 11.12 min West
* 7 000.5 Speed over ground, Knots
* 8 054.7 Course Made Good, True north
* 9 181194 Date of fix 18 November 1994
* 10,11 020.3,E Magnetic variation 20.3 deg East
* 12 A FAA mode indicator (NMEA 2.3 and later)
* see faa_mode() for possible mode values
* 13 V Nav Status (NMEA 4.1 and later)
* A=autonomous,
* D=differential,
* E=Estimated,
* M=Manual input mode
* N=not valid,
* S=Simulator,
* V = Valid
* *68 mandatory nmea_checksum
*
* SiRF chipsets don't return either Mode Indicator or magnetic variation.
*/
gps_mask_t mask = ONLINE_SET;
char status = field[2][0];
int newstatus;
switch (status) {
default:
/* missing */
/* FALLTHROUGH */
case 'V':
/* Invalid */
session->gpsdata.status = STATUS_NO_FIX;
session->newdata.mode = MODE_NO_FIX;
mask |= STATUS_SET | MODE_SET;
break;
case 'D':
/* Differential Fix */
/* FALLTHROUGH */
case 'A':
/* Valid Fix */
/*
* The MTK3301, Royaltek RGM-3800, and possibly other
* devices deliver bogus time values when the navigation
* warning bit is set.
*/
if ('\0' != field[1][0] &&
9 < count &&
'\0' != field[9][0]) {
if (0 == merge_hhmmss(field[1], session) &&
0 == merge_ddmmyy(field[9], session)) {
/* got a good data/time */
mask |= TIME_SET;
register_fractional_time(field[0], field[1], session);
}
}
/* else, no point to the time only case, no regressions with that */
if (0 == do_lat_lon(&field[3], &session->newdata)) {
newstatus = STATUS_FIX;
mask |= LATLON_SET;
if (MODE_2D >= session->gpsdata.fix.mode) {
/* we have at least a 2D fix */
/* might cause blinking */
session->newdata.mode = MODE_2D;
mask |= MODE_SET;
}
} else {
newstatus = STATUS_NO_FIX;
session->newdata.mode = MODE_NO_FIX;
mask |= MODE_SET;
}
if ('\0' != field[7][0]) {
session->newdata.speed = safe_atof(field[7]) * KNOTS_TO_MPS;
mask |= SPEED_SET;
}
if ('\0' != field[8][0]) {
session->newdata.track = safe_atof(field[8]);
mask |= TRACK_SET;
}
if (count >= 12) {
newstatus = faa_mode(field[12][0]);
}
/*
* This copes with GPSes like the Magellan EC-10X that *only* emit
* GPRMC. In this case we set mode and status here so the client
* code that relies on them won't mistakenly believe it has never
* received a fix.
*/
if (3 < session->gpsdata.satellites_used) {
/* 4 sats used means 3D */
session->newdata.mode = MODE_3D;
mask |= MODE_SET;
} else if (0 != isfinite(session->gpsdata.fix.altitude)) {
/* we probably have at least a 3D fix */
/* this handles old GPS that do not report 3D */
session->newdata.mode = MODE_3D;
mask |= MODE_SET;
}
session->gpsdata.status = newstatus;
}
gpsd_log(&session->context->errout, LOG_DATA,
"RMC: ddmmyy=%s hhmmss=%s lat=%.2f lon=%.2f "
"speed=%.2f track=%.2f mode=%d status=%d\n",
field[9], field[1],
session->newdata.latitude,
session->newdata.longitude,
session->newdata.speed,
session->newdata.track,
session->newdata.mode,
session->gpsdata.status);
return mask;
}
/* Geographic position - Latitude, Longitude */
static gps_mask_t processGLL(int count, char *field[],
struct gps_device_t *session)
{
/* Introduced in NMEA 3.0.
*
* $GPGLL,4916.45,N,12311.12,W,225444,A,A*5C
*
* 1,2: 4916.46,N Latitude 49 deg. 16.45 min. North
* 3,4: 12311.12,W Longitude 123 deg. 11.12 min. West
* 5: 225444 Fix taken at 22:54:44 UTC
* 6: A Data valid
* 7: A Autonomous mode
* 8: *5C Mandatory NMEA checksum
*
* 1,2 Latitude, N (North) or S (South)
* 3,4 Longitude, E (East) or W (West)
* 5 UTC of position
* 6 A = Active, V = Invalid data
* 7 Mode Indicator
* See faa_mode() for possible mode values.
*
* I found a note at <http://www.secoh.ru/windows/gps/nmfqexep.txt>
* indicating that the Garmin 65 does not return time and status.
* SiRF chipsets don't return the Mode Indicator.
* This code copes gracefully with both quirks.
*
* Unless you care about the FAA indicator, this sentence supplies nothing
* that GPRMC doesn't already. But at least two (Garmin GPS 48 and
* Magellan Triton 400) actually ship updates in GLL that aren't redundant.
*
*/
char *status = field[7];
gps_mask_t mask = ONLINE_SET;
if (field[5][0] != '\0') {
if (0 == merge_hhmmss(field[5], session)) {
register_fractional_time(field[0], field[5], session);
if (session->nmea.date.tm_year == 0)
gpsd_log(&session->context->errout, LOG_WARN,
"can't use GLL time until after ZDA or RMC"
" has supplied a year.\n");
else {
mask = TIME_SET;
}
}
}
if ('\0' == field[6][0] ||
'V' == field[6][0]) {
/* Invalid */
session->gpsdata.status = STATUS_NO_FIX;
session->newdata.mode = MODE_NO_FIX;
mask |= STATUS_SET | MODE_SET;
} else if ('A' == field[6][0] &&
(count < 8 || *status != 'N') &&
0 == do_lat_lon(&field[1], &session->newdata)) {
int newstatus;
mask |= LATLON_SET;
newstatus = STATUS_FIX;
if (count >= 8) {
newstatus = faa_mode(*status);
}
/*
* This is a bit dodgy. Technically we shouldn't set the mode
* bit until we see GSA, or similar. But it may be later in the
* cycle, some devices like the FV-18 don't send it by default,
* and elsewhere in the code we want to be able to test for the
* presence of a valid fix with mode > MODE_NO_FIX.
*/
if (0 != isfinite(session->gpsdata.fix.altitude)) {
session->newdata.mode = MODE_3D;
mask |= MODE_SET;
} else if (3 < session->gpsdata.satellites_used) {
/* 4 sats used means 3D */
session->newdata.mode = MODE_3D;
mask |= MODE_SET;
} else if (MODE_2D > session->gpsdata.fix.mode ||
0 == isfinite(session->oldfix.altitude)) {
session->newdata.mode = MODE_2D;
mask |= MODE_SET;
}
session->gpsdata.status = newstatus;
} else {
session->gpsdata.status = STATUS_NO_FIX;
session->newdata.mode = MODE_NO_FIX;
mask |= STATUS_SET | MODE_SET;
}
gpsd_log(&session->context->errout, LOG_DATA,
"GLL: hhmmss=%s lat=%.2f lon=%.2f mode=%d status=%d\n",
field[5],
session->newdata.latitude,
session->newdata.longitude,
session->newdata.mode,
session->gpsdata.status);
return mask;
}
/* Geographic position - Latitude, Longitude, and more */
static gps_mask_t processGNS(int count UNUSED, char *field[],
struct gps_device_t *session)
{
/* Introduced in NMEA 4.0?
*
* This mostly duplicates RMC, except for the multi GNSS mode
* indicatore.
*
* Example. Ignore the line break.
* $GPGNS,224749.00,3333.4268304,N,11153.3538273,W,D,19,0.6,406.110,
* -26.294,6.0,0138,S,*6A
*
* 1: 224749.00 UTC HHMMSS.SS. 22:47:49.00
* 2: 3333.4268304 Latitude DDMM.MMMMM. 33 deg. 33.4268304 min
* 3: N Latitude North
* 4: 12311.12 Longitude 111 deg. 53.3538273 min
* 5: W Longitude West
* 6: D FAA mode indicator
* see faa_mode() for possible mode values
* May be one to four characters.
* Char 1 = GPS
* Char 2 = GLONASS
* Char 3 = ?
* Char 4 = ?
* 7: 19 Number of Satellites used in solution
* 8: 0.6 HDOP
* 9: 406110 Altitude in meters
* 10: -26.294 Geoid separation in meters
* 11: 6.0 Age of differential corrections, in seconds
* 12: 0138 Differential reference station ID
* 13: S NMEA 4.1+ Navigation status
* S = Safe
* C = Caution
* U = Unsafe
* V = Not valid for navigation
* 8: *6A Mandatory NMEA checksum
*
*/
int newstatus;
int satellites_used;
gps_mask_t mask = ONLINE_SET;
if (field[1][0] != '\0') {
if (0 == merge_hhmmss(field[1], session)) {
register_fractional_time(field[0], field[1], session);
if (session->nmea.date.tm_year == 0) {
gpsd_log(&session->context->errout, LOG_WARN,
"can't use GNS time until after ZDA or RMC"
" has supplied a year.\n");
} else {
mask = TIME_SET;
}
}
}
/* FAA mode: not valid, ignore
* Yes, in 2019 a GLONASS only fix may be valid, but not worth
* the confusion */
if ('\0' == field[6][0] || /* FAA mode: missing */
'N' == field[6][0]) { /* FAA mode: not valid */
session->newdata.mode = MODE_NO_FIX;
mask |= MODE_SET;
return mask;
}
/* navigation status, assume S=safe and C=caution are OK */
/* can be missing on valid fix */
if ('U' == field[13][0] || /* Unsafe */
'V' == field[13][0]) { /* not valid */
return mask;
}
satellites_used = atoi(field[7]);
if (0 == do_lat_lon(&field[2], &session->newdata)) {
mask |= LATLON_SET;
session->newdata.mode = MODE_2D;
if ('\0' != field[9][0]) {
session->newdata.altitude = safe_atof(field[9]);
if (0 != isfinite(session->newdata.altitude)) {
mask |= ALTITUDE_SET;
if (3 < satellites_used) {
/* more than 3 sats used means 3D */
session->newdata.mode = MODE_3D;
}
}
}
} else {
session->newdata.mode = MODE_NO_FIX;
mask |= MODE_SET;
}
if (field[8][0] != '\0') {
session->gpsdata.dop.hdop = safe_atof(field[8]);
}
newstatus = faa_mode(field[6][0]);
session->gpsdata.status = newstatus;
mask |= MODE_SET;
gpsd_log(&session->context->errout, LOG_DATA,
"GNS: hhmmss=%s lat=%.2f lon=%.2f mode=%d status=%d\n",
field[1],
session->newdata.latitude,
session->newdata.longitude,
session->newdata.mode,
session->gpsdata.status);
return mask;
}
/* Global Positioning System Fix Data */
static gps_mask_t processGGA(int c UNUSED, char *field[],
struct gps_device_t *session)
{
/*
* GGA,123519,4807.038,N,01131.324,E,1,08,0.9,545.4,M,46.9,M, , *42
* 1 123519 Fix taken at 12:35:19 UTC
* 2,3 4807.038,N Latitude 48 deg 07.038' N
* 4,5 01131.324,E Longitude 11 deg 31.324' E
* 6 1 Fix quality:
* 0 = invalid,
* 1 = GPS,
* u-blox may use 1 for Estimated
* 2 = DGPS,
* 3 = PPS (Precise Position Service),
* 4 = RTK (Real Time Kinematic) with fixed integers,
* 5 = Float RTK,
* 6 = Estimated,
* 7 = Manual,
* 8 = Simulator
* 7 08 Number of satellites in use
* 8 0.9 Horizontal dilution of position
* 9,10 545.4,M Altitude, Metres above mean sea level
* 11,12 46.9,M Height of geoid (mean sea level) above WGS84
* ellipsoid, in Meters
* 13 33 time in seconds since last DGPS update
* usually empty
* 14 1023 DGPS station ID number (0000-1023)
* usually empty
*
* Some GPS, like the SiRFstarV in NMEA mode, send both GPGSA and
* GLGPSA with identical data.
*/
gps_mask_t mask = ONLINE_SET;
int newstatus;
char last_last_gga_talker = session->nmea.last_gga_talker;
int fix;
char *altitude = field[9];
int satellites_visible;
session->nmea.last_gga_talker = field[0][1];
if (0 == strlen(field[6])) {
/* no data is no data, assume no fix
* the test/daemon/myguide-3100.log shows lat/lon/alt but
* no status, and related RMC shows no fix. */
fix = -1;
} else {
fix = atoi(field[6]);
}
switch (fix) {
case 0: /* no fix */
newstatus = STATUS_NO_FIX;
break;
case 1:
/* could be 2D, 3D, GNSSDR */
newstatus = STATUS_FIX;
break;
case 2: /* differential */
newstatus = STATUS_DGPS_FIX;
break;
case 3:
/* GPS PPS, fix valid, could be 2D, 3D, GNSSDR */
newstatus = STATUS_FIX;
break;
case 4: /* RTK integer */
newstatus = STATUS_RTK_FIX;
break;
case 5: /* RTK float */
newstatus = STATUS_RTK_FLT;
break;
case 6:
/* dead reckoning, could be valid or invalid */
newstatus = STATUS_DR;
break;
case 7:
/* manual input, surveyed */
newstatus = STATUS_TIME;
break;
case 8:
/* simulated mode */
/* Garmin GPSMAP and Gecko sends an 8, but undocumented why */
newstatus = STATUS_SIM;
break;
default:
newstatus = -1;
break;
}
if (0 <= newstatus) {
session->gpsdata.status = newstatus;
mask = STATUS_SET;
}
/*
* There are some receivers (the Trimble Placer 450 is an example) that
* don't ship a GSA with mode 1 when they lose satellite lock. Instead
* they just keep reporting GGA and GSA on subsequent cycles with the
* timestamp not advancing and a bogus mode.
*
* On the assumption that GGA is only issued once per cycle we can
* detect this here (it would be nicer to do it on GSA but GSA has
* no timestamp).
*
* SiRFstarV breaks this assumption, sending GGA with different
* talker IDs.
*/
if ('\0' != last_last_gga_talker &&
last_last_gga_talker != session->nmea.last_gga_talker) {
/* skip the time check */
session->nmea.latch_mode = 0;
} else {
session->nmea.latch_mode = strncmp(field[1],
session->nmea.last_gga_timestamp,
sizeof(session->nmea.last_gga_timestamp))==0;
}
if (session->nmea.latch_mode) {
session->gpsdata.status = STATUS_NO_FIX;
session->newdata.mode = MODE_NO_FIX;
gpsd_log(&session->context->errout, LOG_PROG,
"xxGGA: latch mode\n");
} else
(void)strlcpy(session->nmea.last_gga_timestamp, field[1],
sizeof(session->nmea.last_gga_timestamp));
/* satellites_visible is used as an accumulator in xxGSV
* so if we set it here we break xxGSV
* Some GPS, like SiRFstarV NMEA, report per GNSS used
* counts in GPGGA and GLGGA.
* session->gpsdata.satellites_visible = atoi(field[7]);
*/
satellites_visible = atoi(field[7]);
if (0 == merge_hhmmss(field[1], session)) {
register_fractional_time(field[0], field[1], session);
if (session->nmea.date.tm_year == 0)
gpsd_log(&session->context->errout, LOG_WARN,
"can't use GGA time until after ZDA or RMC"
" has supplied a year.\n");
else {
mask |= TIME_SET;
}
}
if (0 == do_lat_lon(&field[2], &session->newdata)) {
session->newdata.mode = MODE_2D;
mask |= LATLON_SET;
if ('\0' == field[11][0]) {
session->gpsdata.separation =
wgs84_separation(session->newdata.latitude,
session->newdata.longitude);
} else {
session->gpsdata.separation = safe_atof(field[11]);
}
/*
* SiRF chipsets up to version 2.2 report a null altitude field.
* See <http://www.sirf.com/Downloads/Technical/apnt0033.pdf>.
* If we see this, force mode to 2D at most.
*/
if ('\0' != altitude[0]) {
session->newdata.altitude = safe_atof(altitude);
mask |= ALTITUDE_SET;
/*
* This is a bit dodgy. Technically we shouldn't set the mode
* bit until we see GSA. But it may be later in the cycle,
* some devices like the FV-18 don't send it by default, and
* elsewhere in the code we want to be able to test for the
* presence of a valid fix with mode > MODE_NO_FIX.
*
* Use satellites_visible as double check on MODE_3D
*/
if (4 <= satellites_visible) {
session->newdata.mode = MODE_3D;
}
}
if (3 > satellites_visible) {
session->newdata.mode = MODE_NO_FIX;
}
} else {
session->newdata.mode = MODE_NO_FIX;
}
mask |= MODE_SET;
if ('\0' != field[8][0]) {
session->gpsdata.dop.hdop = safe_atof(field[8]);
}
gpsd_log(&session->context->errout, LOG_DATA,
"GGA: hhmmss=%s lat=%.2f lon=%.2f alt=%.2f mode=%d status=%d\n",
field[1],
session->newdata.latitude,
session->newdata.longitude,
session->newdata.altitude,
session->newdata.mode,
session->gpsdata.status);
return mask;
}
static gps_mask_t processGST(int count, char *field[],
struct gps_device_t *session)
/* GST - GPS Pseudorange Noise Statistics */
{
/*
* GST,hhmmss.ss,x,x,x,x,x,x,x,*hh
* 1 UTC time of associated GGA fix
* 2 Total RMS standard deviation of ranges inputs to the nav solution
* 3 Standard deviation (meters) of semi-major axis of error ellipse
* 4 Standard deviation (meters) of semi-minor axis of error ellipse
* 5 Orientation of semi-major axis of error ellipse (true north degrees)
* 6 Standard deviation (meters) of latitude error
* 7 Standard deviation (meters) of longitude error
* 8 Standard deviation (meters) of altitude error
* 9 Checksum
*/
gps_mask_t mask = ONLINE_SET;
if (count < 8) {
return mask;
}
#define PARSE_FIELD(n) (*field[n]!='\0' ? safe_atof(field[n]) : NAN)
/* note this is not full UTC, just HHMMSS.ss */
/* this is not the current time,
* it references another GPA of the same stamp. So do not set
* any time stamps with it */
session->gpsdata.gst.utctime = PARSE_FIELD(1);
session->gpsdata.gst.rms_deviation = PARSE_FIELD(2);
session->gpsdata.gst.smajor_deviation = PARSE_FIELD(3);
session->gpsdata.gst.sminor_deviation = PARSE_FIELD(4);
session->gpsdata.gst.smajor_orientation = PARSE_FIELD(5);
session->gpsdata.gst.lat_err_deviation = PARSE_FIELD(6);
session->gpsdata.gst.lon_err_deviation = PARSE_FIELD(7);
session->gpsdata.gst.alt_err_deviation = PARSE_FIELD(8);
#undef PARSE_FIELD
/* add in the time of start of today */
/* since it is NOT current time, do not register_fractional_time() */
session->gpsdata.gst.utctime += mkgmtime(&session->nmea.date);
gpsd_log(&session->context->errout, LOG_DATA,
"GST: utc = %.3f, rms = %.2f, maj = %.2f, min = %.2f,"
" ori = %.2f, lat = %.2f, lon = %.2f, alt = %.2f\n",
session->gpsdata.gst.utctime,
session->gpsdata.gst.rms_deviation,
session->gpsdata.gst.smajor_deviation,
session->gpsdata.gst.sminor_deviation,
session->gpsdata.gst.smajor_orientation,
session->gpsdata.gst.lat_err_deviation,
session->gpsdata.gst.lon_err_deviation,
session->gpsdata.gst.alt_err_deviation);
mask = GST_SET | ONLINE_SET;
return mask;
}
/* convert NMEA sigid to ublox sigid */
static unsigned char nmea_sigid_to_ubx(unsigned char nmea_sigid)
{
unsigned char ubx_sigid = 0;
switch (nmea_sigid) {
default:
/* FALLTHROUGH */
case 0:
/* missing, assume GPS L1 */
ubx_sigid = 0;
break;
case 1:
/* L1 */
ubx_sigid = 0;
break;
case 2:
/* E5, could be 5 or 6. */
ubx_sigid = 5;
break;
case 3:
/* B2 or L2, could be 2 or 3. */
ubx_sigid = 2;
break;
case 5:
/* L2 */
ubx_sigid = 4;
break;
case 6:
/* L2CL */
ubx_sigid = 3;
break;
case 7:
/* E1, could be 0 or 1. */
ubx_sigid = 0;
break;
}
return ubx_sigid;
}
/* Deal with range-mapping attempts to use IDs 1-32 by Beidou, etc.
*
* See struct satellite_t in gps.h for ubx and nmea gnssid and svid mappings
*
* char *talker -- NMEA talker string
* int nmea_satnum -- NMEA (All ver) satellite number (kinda the PRN)
* int nmea_gnssid -- NMEA 4.10 gnssid, if known, otherwise zero
* unsigned char *ubx_gnssid -- returned u-blox gnssid
* unsigned char *ubx_svid -- returned u-blox gnssid
*
* Return the NMEA 2.x to 4.0 extended PRN
*/
static int nmeaid_to_prn(char *talker, int nmea_satnum,
int nmea_gnssid,
unsigned char *ubx_gnssid,
unsigned char *ubx_svid)
{