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|
/* $OpenBSD: tty_nmea.c,v 1.13 2006/11/29 13:26:50 mbalmer Exp $ */
/*
* Copyright (c) 2006 Marc Balmer <mbalmer@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* line discipline to decode NMEA 0183 data */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/queue.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/sensors.h>
#include <sys/tty.h>
#include <sys/conf.h>
#include <sys/time.h>
#ifdef NMEA_DEBUG
#define DPRINTFN(n, x) do { if (nmeadebug > (n)) printf x; } while (0)
int nmeadebug = 0;
#else
#define DPRINTFN(n, x)
#endif
#define DPRINTF(x) DPRINTFN(0, x)
int nmeaopen(dev_t, struct tty *);
int nmeaclose(struct tty *, int);
int nmeainput(int, struct tty *);
void nmeaattach(int);
#define NMEAMAX 82
#define MAXFLDS 16
int nmea_count;
struct nmea {
char cbuf[NMEAMAX];
struct sensor time;
#ifdef NMEA_DEBUG
struct sensor skew; /* soft to tty timestamp skew */
#endif
struct timespec ts; /* soft timestamp */
struct timeval tv; /* tty timestamp */
int64_t last; /* last time rcvd */
int sync;
int pos;
char mode; /* GPS mode */
};
/* NMEA decoding */
void nmea_scan(struct nmea *, struct tty *);
void nmea_gprmc(struct nmea *, struct tty *, char *fld[], int fldcnt);
/* date and time conversion */
int nmea_date_to_nano(char *s, int64_t *nano);
int nmea_time_to_nano(char *s, int64_t *nano);
void
nmeaattach(int dummy)
{
}
int
nmeaopen(dev_t dev, struct tty *tp)
{
struct proc *p = curproc; /* XXX */
struct nmea *np;
int error;
if (tp->t_line == NMEADISC)
return (ENODEV);
if ((error = suser(p, 0)) != 0)
return (error);
np = malloc(sizeof(struct nmea), M_WAITOK, M_DEVBUF);
bzero(np, sizeof(*np));
snprintf(np->time.device, sizeof(np->time.device), "nmea%d",
nmea_count++);
np->time.status = SENSOR_S_UNKNOWN;
np->time.type = SENSOR_TIMEDELTA;
np->time.flags = SENSOR_FINVALID;
sensor_add(&np->time);
#ifdef NMEA_DEBUG
snprintf(np->skew.device, sizeof(np->skew.device), "skew%d",
nmea_count - 1);
snprintf(np->skew.desc, sizeof(np->skew.desc),
"nmea%d timestamp skew", nmea_count - 1);
np->skew.status = SENSOR_S_UNKNOWN;
np->skew.type = SENSOR_TIMEDELTA;
np->skew.flags = SENSOR_FINVALID;
sensor_add(&np->skew);
#endif
np->sync = 1;
tp->t_sc = (caddr_t)np;
error = linesw[TTYDISC].l_open(dev, tp);
if (error) {
free(np, M_DEVBUF);
tp->t_sc = NULL;
}
return (error);
}
int
nmeaclose(struct tty *tp, int flags)
{
struct nmea *np = (struct nmea *)tp->t_sc;
tp->t_line = TTYDISC; /* switch back to termios */
sensor_del(&np->time);
#ifdef NMEA_DEBUG
sensor_del(&np->skew);
#endif
free(np, M_DEVBUF);
tp->t_sc = NULL;
nmea_count--;
return linesw[TTYDISC].l_close(tp, flags);
}
/* collect NMEA sentence from tty */
int
nmeainput(int c, struct tty *tp)
{
struct nmea *np = (struct nmea *)tp->t_sc;
switch (c) {
case '$':
/*
* Capture the moment, take a soft timestamp in any case,
* it is possible that tty timestamping has been requested
* but device does not provide a PPS signal. In this
* case we use the soft timestamp later.
*/
nanotime(&np->ts);
/* if a tty timestamp is available, copy it now */
if (tp->t_flags & (TS_TSTAMPDCDSET | TS_TSTAMPDCDCLR |
TS_TSTAMPCTSSET | TS_TSTAMPCTSCLR)) {
np->tv.tv_sec = tp->t_tv.tv_sec;
np->tv.tv_usec = tp->t_tv.tv_usec;
}
np->pos = 0;
np->sync = 0;
break;
case '\r':
case '\n':
if (!np->sync) {
np->cbuf[np->pos] = '\0';
nmea_scan(np, tp);
np->sync = 1;
}
break;
default:
if (!np->sync && np->pos < (NMEAMAX - 1))
np->cbuf[np->pos++] = c;
break;
}
/* pass data to termios */
return linesw[TTYDISC].l_rint(c, tp);
}
/* Scan the NMEA sentence just received */
void
nmea_scan(struct nmea *np, struct tty *tp)
{
int fldcnt = 0, cksum = 0, msgcksum, n;
char *fld[MAXFLDS], *cs;
/* split into fields and calc checksum */
fld[fldcnt++] = &np->cbuf[0]; /* message type */
for (cs = NULL, n = 0; n < np->pos && cs == NULL; n++) {
switch (np->cbuf[n]) {
case '*':
np->cbuf[n] = '\0';
cs = &np->cbuf[n + 1];
break;
case ',':
if (fldcnt < MAXFLDS) {
cksum ^= np->cbuf[n];
np->cbuf[n] = '\0';
fld[fldcnt++] = &np->cbuf[n + 1];
} else {
DPRINTF(("nr of fields in %s sentence exceeds "
"maximum of %d\n", fld[0], MAXFLDS));
return;
}
break;
default:
cksum ^= np->cbuf[n];
}
}
/* if we have a checksum, verify it */
if (cs != NULL) {
msgcksum = 0;
while (*cs) {
if ((*cs >= '0' && *cs <= '9') ||
(*cs >= 'A' && *cs <= 'F')) {
if (msgcksum)
msgcksum <<= 4;
if (*cs >= '0' && *cs<= '9')
msgcksum += *cs - '0';
else if (*cs >= 'A' && *cs <= 'F')
msgcksum += 10 + *cs - 'A';
cs++;
} else {
DPRINTF(("bad char %c in checksum\n", *cs));
return;
}
}
if (msgcksum != cksum) {
DPRINTF(("cksum mismatch\n"));
return;
}
}
/* check message type */
if (!strcmp(fld[0], "GPRMC"))
nmea_gprmc(np, tp, fld, fldcnt);
}
/* Decode the recommended minimum specific GPS/TRANSIT data */
void
nmea_gprmc(struct nmea *np, struct tty *tp, char *fld[], int fldcnt)
{
int64_t date_nano, time_nano, nmea_now;
if (fldcnt != 12 && fldcnt != 13) {
DPRINTF(("gprmc: field count mismatch, %d\n", fldcnt));
return;
}
if (nmea_time_to_nano(fld[1], &time_nano)) {
DPRINTF(("gprmc: illegal time, %s\n", fld[1]));
return;
}
if (nmea_date_to_nano(fld[9], &date_nano)) {
DPRINTF(("gprmc: illegal date, %s\n", fld[9]));
return;
}
nmea_now = date_nano + time_nano;
if (nmea_now <= np->last) {
DPRINTF(("gprmc: time not monotonically increasing\n"));
return;
}
np->last = nmea_now;
/*
* if tty timestamping on DCD or CTS is used, take the timestamp
* from the tty, else use the timestamp taken on the initial '$'
* character.
*/
if (tp->t_flags & (TS_TSTAMPDCDSET | TS_TSTAMPDCDCLR |
TS_TSTAMPCTSSET | TS_TSTAMPCTSCLR)) {
np->time.value = np->tv.tv_sec * 1000000000LL +
np->tv.tv_usec * 1000LL - nmea_now;
np->time.tv.tv_sec = np->tv.tv_sec;
np->time.tv.tv_usec = np->tv.tv_usec;
#ifdef NMEA_DEBUG
/*
* If we got a tty timestamp, provide the skew to the
* soft timestamp (taken at the '$' character) in a
* second timedelta sensor.
*/
np->skew.value = (np->ts.tv_sec * 1000000000LL +
np->ts.tv_nsec - nmea_now) - np->time.value;
np->skew.tv.tv_sec = np->tv.tv_sec;
np->skew.tv.tv_usec = np->tv.tv_usec;
if (np->skew.status == SENSOR_S_UNKNOWN) {
np->skew.status = SENSOR_S_CRIT;
np->skew.flags &= ~SENSOR_FINVALID;
}
#endif
} else {
np->time.value = np->ts.tv_sec * 1000000000LL +
np->ts.tv_nsec - nmea_now;
np->time.tv.tv_sec = np->ts.tv_sec;
np->time.tv.tv_usec = np->ts.tv_nsec / 1000L;
#ifdef NMEA_DEBUG
if (np->skew.status == SENSOR_S_CRIT) {
np->skew.value = 0LL;
np->skew.value = SENSOR_S_UNKNOWN;
np->skew.flags |= SENSOR_FINVALID;
}
#endif
}
if (np->time.status == SENSOR_S_UNKNOWN) {
np->time.status = SENSOR_S_OK;
np->time.flags &= ~SENSOR_FINVALID;
if (fldcnt != 13)
strlcpy(np->time.desc, "GPS", sizeof(np->time.desc));
}
if (fldcnt == 13 && *fld[12] != np->mode) {
np->mode = *fld[12];
switch (np->mode) {
case 'S':
strlcpy(np->time.desc, "GPS simulated",
sizeof(np->time.desc));
break;
case 'E':
strlcpy(np->time.desc, "GPS estimated",
sizeof(np->time.desc));
break;
case 'A':
strlcpy(np->time.desc, "GPS autonomous",
sizeof(np->time.desc));
break;
case 'D':
strlcpy(np->time.desc, "GPS differential",
sizeof(np->time.desc));
break;
case 'N':
strlcpy(np->time.desc, "GPS not valid",
sizeof(np->time.desc));
break;
default:
strlcpy(np->time.desc, "GPS unknown",
sizeof(np->time.desc));
DPRINTF(("gprmc: unknown mode '%c'\n", np->mode));
}
}
switch (*fld[2]) {
case 'A':
np->time.status = SENSOR_S_OK;
break;
case 'V':
np->time.status = SENSOR_S_WARN;
break;
default:
DPRINTF(("gprmc: unknown warning indication\n"));
}
}
/*
* convert a NMEA 0183 formatted date string to seconds since the epoch
* the string must be of the form DDMMYY
* return (0) on success, (-1) if illegal characters are encountered
*/
int
nmea_date_to_nano(char *s, int64_t *nano)
{
struct clock_ymdhms ymd;
time_t secs;
char *p;
int n;
/* make sure the input contains only numbers and is six digits long */
for (n = 0, p = s; n < 6 && *p && *p >= '0' && *p <= '9'; n++, p++)
;
if (n != 6 || (*p != '\0'))
return (-1);
ymd.dt_year = 2000 + (s[4] - '0') * 10 + (s[5] - '0');
ymd.dt_mon = (s[2] - '0') * 10 + (s[3] - '0');
ymd.dt_day = (s[0] - '0') * 10 + (s[1] - '0');
ymd.dt_hour = ymd.dt_min = ymd.dt_sec = 0;
secs = clock_ymdhms_to_secs(&ymd);
*nano = secs * 1000000000LL;
return (0);
}
/*
* convert NMEA 0183 formatted time string to nanoseconds since midnight
* the string must be of the form HHMMSS[.[sss]]
* (e.g. 143724 or 143723.615)
* return (0) on success, (-1) if illegal characters are encountered
*/
int
nmea_time_to_nano(char *s, int64_t *nano)
{
long fac = 36000L, div = 6L, secs = 0L, frac;
char ul = '2';
int n;
for (n = 0, secs = 0; fac && *s && *s >= '0' && *s <= ul; s++, n++) {
secs += (*s - '0') * fac;
div = 16 - div;
fac /= div;
switch (n) {
case 0:
if (*s <= '1')
ul = '9';
else
ul = '3';
break;
case 1:
case 3:
ul = '5';
break;
case 2:
case 4:
ul = '9';
break;
}
}
if (fac)
return (-1);
div = 1L;
frac = 0L;
/* handle fractions of a second, max. 6 digits */
if (*s == '.') {
for (++s; div < 1000000 && *s && *s >= '0' && *s <= '9'; s++) {
frac *= 10;
frac += (*s - '0');
div *= 10;
}
}
if (*s != '\0')
return (-1);
*nano = secs * 1000000000LL + (int64_t)frac * (1000000000 / div);
return (0);
}
|