refclock_mx4200.c

网络时间协议NTP 源码 版本v4.2.0b 该源码用于linux平台下

	/*
	 * "000" Initialization/Mode Control - Part A
	 * Fix to our averaged position.
	 */
	if (up->central_meridian != NOT_INITIALIZED) {
		up->avg_lon += up->central_meridian;
		if (up->avg_lon < -180.0) up->avg_lon += 360.0;
		if (up->avg_lon >  180.0) up->avg_lon -= 360.0;
	}

	if (up->avg_lat >= 0.0) {
		lat = up->avg_lat;
		nsc = 'N';
	} else {
		lat = up->avg_lat * (-1.0);
		nsc = 'S';
	}
	if (up->avg_lon >= 0.0) {
		lon = up->avg_lon;
		ewc = 'E';
	} else {
		lon = up->avg_lon * (-1.0);
		ewc = 'W';
	}
	alt = up->avg_alt;
	minute = (lat - (double)(int)lat) * 60.0;
	sprintf(lats,"%02d%02.4f", (int)lat, minute);
	minute = (lon - (double)(int)lon) * 60.0;
	sprintf(lons,"%03d%02.4f", (int)lon, minute);

	mx4200_send(peer, "%s,%03d,,,,,%s,%c,%s,%c,%.2f,%d", pmvxg,
	    PMVXG_S_INITMODEA,
	    /* day of month */
	    /* month of year */
	    /* year */
	    /* gmt */
	    lats,	/* latitude   DDMM.MMMM */
	    nsc,	/* north/south */
	    lons,	/* longitude DDDMM.MMMM */
	    ewc,	/* east/west */
	    alt,	/* Altitude */
	    1);		/* Altitude Reference (0=WGS84 ellipsoid, 1=MSL geoid)*/

	msyslog(LOG_DEBUG,
	    "mx4200: reconfig to fixed location: %s %c, %s %c, %.2f m",
		lats, nsc, lons, ewc, alt );

}

/*
 * mx4200_poll - mx4200 watchdog routine
 */
static void
mx4200_poll(
	int unit,
	struct peer *peer
	)
{
	register struct mx4200unit *up;
	struct refclockproc *pp;

	pp = peer->procptr;
	up = (struct mx4200unit *)pp->unitptr;

	/*
	 * You don't need to poll this clock.  It puts out timecodes
	 * once per second.  If asked for a timestamp, take note.
	 * The next time a timecode comes in, it will be fed back.
	 */

	/*
	 * If we haven't had a response in a while, reset the receiver.
	 */
	if (up->pollcnt > 0) {
		up->pollcnt--;
	} else {
		refclock_report(peer, CEVNT_TIMEOUT);

		/*
		 * Request a "000" status message which should trigger a
		 * reconfig
		 */
		mx4200_send(peer, "%s,%03d",
		    "CDGPQ",		/* query from CDU to GPS */
		    PMVXG_D_STATUS);	/* label of desired sentence */
	}

	/*
	 * polled every 64 seconds. Ask mx4200_receive to hand in
	 * a timestamp.
	 */
	up->polled = 1;
	pp->polls++;

	/*
	 * Output receiver status information.
	 */
	if ((up->log_time > 0) && (current_time > up->log_time)) {
		up->log_time = 0;
		/*
		 * Output the following messages once, for debugging.
		 *    "004" Mode Data
		 *    "523" Time Recovery Parameters
		 */
		mx4200_send(peer, "%s,%03d", "CDGPQ", PMVXG_D_MODEDATA);
		mx4200_send(peer, "%s,%03d", "CDGPQ", PMVXG_D_TRECOVUSEAGE);
	}
}

static char char2hex[] = "0123456789ABCDEF";

/*
 * mx4200_receive - receive gps data
 */
static void
mx4200_receive(
	struct recvbuf *rbufp
	)
{
	register struct mx4200unit *up;
	struct refclockproc *pp;
	struct peer *peer;
	char *cp;
	int sentence_type;
	u_char ck;

	/*
	 * Initialize pointers and read the timecode and timestamp.
	 */
	peer = (struct peer *)rbufp->recv_srcclock;
	pp = peer->procptr;
	up = (struct mx4200unit *)pp->unitptr;

	/*
	 * If operating mode has been changed, then reinitialize the receiver
	 * before doing anything else.
	 */
	if ((pp->sloppyclockflag & CLK_FLAG2) !=
	    (up->sloppyclockflag & CLK_FLAG2)) {
		up->sloppyclockflag = pp->sloppyclockflag;
		mx4200_debug(peer,
		    "mx4200_receive: mode switch: reset receiver\n");
		mx4200_config(peer);
		return;
	}
	up->sloppyclockflag = pp->sloppyclockflag;

	/*
	 * Read clock output.  Automatically handles STREAMS, CLKLDISC.
	 */
	pp->lencode = refclock_gtlin(rbufp, pp->a_lastcode, BMAX, &pp->lastrec);

	/*
	 * There is a case where <cr><lf> generates 2 timestamps.
	 */
	if (pp->lencode == 0)
		return;

	up->pollcnt = 2;
	pp->a_lastcode[pp->lencode] = '\0';
	record_clock_stats(&peer->srcadr, pp->a_lastcode);
	mx4200_debug(peer, "mx4200_receive: %d %s\n",
		     pp->lencode, pp->a_lastcode);

	/*
	 * The structure of the control port sentences is based on the
	 * NMEA-0183 Standard for interfacing Marine Electronics
	 * Navigation Devices (Version 1.5)
	 *
	 *	$PMVXG,XXX, ....................*CK<cr><lf>
	 *
	 *		$	Sentence Start Identifier (reserved char)
	 *			   (Start-of-Sentence Identifier)
	 *		P	Special ID (Proprietary)
	 *		MVX	Originator ID (Magnavox)
	 *		G	Interface ID (GPS)
	 *		,	Field Delimiters (reserved char)
	 *		XXX	Sentence Type
	 *		......	Data
	 *		*	Checksum Field Delimiter (reserved char)
	 *		CK	Checksum
	 *		<cr><lf> Carriage-Return/Line Feed (reserved chars)
	 *			   (End-of-Sentence Identifier)
	 *
	 * Reject if any important landmarks are missing.
	 */
	cp = pp->a_lastcode + pp->lencode - 3;
	if (cp < pp->a_lastcode || *pp->a_lastcode != '$' || cp[0] != '*' ) {
		mx4200_debug(peer, "mx4200_receive: bad format\n");
		refclock_report(peer, CEVNT_BADREPLY);
		return;
	}

	/*
	 * Check and discard the checksum
	 */
	ck = mx4200_cksum(&pp->a_lastcode[1], pp->lencode - 4);
	if (char2hex[ck >> 4] != cp[1] || char2hex[ck & 0xf] != cp[2]) {
		mx4200_debug(peer, "mx4200_receive: bad checksum\n");
		refclock_report(peer, CEVNT_BADREPLY);
		return;
	}
	*cp = '\0';

	/*
	 * Get the sentence type.
	 */
	sentence_type = 0;
	if ((cp = strchr(pp->a_lastcode, ',')) == NULL) {
		mx4200_debug(peer, "mx4200_receive: no sentence\n");
		refclock_report(peer, CEVNT_BADREPLY);
		return;
	}
	cp++;
	sentence_type = strtol(cp, &cp, 10);

	/*
	 * Process the sentence according to its type.
	 */
	switch (sentence_type) {

	/*
	 * "000" Status message
	 */
	case PMVXG_D_STATUS:
		/*
		 * XXX
		 * Since we configure the receiver to not give us status
		 * messages and since the receiver outputs status messages by
		 * default after being reset to factory defaults when sent the
		 * "$PMVXG,018,C\r\n" message, any status message we get
		 * indicates the reciever needs to be initialized; thus, it is
		 * not necessary to decode the status message.
		 */
		if ((cp = mx4200_parse_s(peer)) != NULL) {
			mx4200_debug(peer,
				     "mx4200_receive: status: %s\n", cp);
		}
		mx4200_debug(peer, "mx4200_receive: reset receiver\n");
		mx4200_config(peer);
		break;

	/*
	 * "021" Position, Height, Velocity message,
	 *  if we are still averaging our position
	 */
	case PMVXG_D_PHV:
		if (!up->known) {
			/*
			 * Parse the message, calculating our averaged position.
			 */
			if ((cp = mx4200_parse_p(peer)) != NULL) {
				mx4200_debug(peer, "mx4200_receive: pos: %s\n", cp);
				return;
			}
			mx4200_debug(peer,
			    "mx4200_receive: position avg %f %.9f %.9f %.4f\n",
			    up->N_fixes, up->avg_lat, up->avg_lon, up->avg_alt);
			/*
			 * Reinitialize as a reference station
			 * if position is well known.
			 */
			if (current_time > up->clamp_time) {
				up->known++;
				mx4200_debug(peer, "mx4200_receive: reconfiguring!\n");
				mx4200_ref(peer);
			}
		}
		break;

	/*
	 * Print to the syslog:
	 * "004" Mode Data
	 * "030" Software Configuration
	 * "523" Time Recovery Parameters Currently in Use
	 */
	case PMVXG_D_MODEDATA:
	case PMVXG_D_SOFTCONF:
	case PMVXG_D_TRECOVUSEAGE:

		if ((cp = mx4200_parse_s(peer)) != NULL) {
			mx4200_debug(peer,
				     "mx4200_receive: multi-record: %s\n", cp);
		}
		break;

	/*
	 * "830" Time Recovery Results message
	 */
	case PMVXG_D_TRECOVOUT:

		/*
		 * Capture the last PPS signal.
		 * Precision timestamp is returned in pp->lastrec
		 */
		if (mx4200_pps(peer) != NULL) {
			mx4200_debug(peer, "mx4200_receive: pps failure\n");
			refclock_report(peer, CEVNT_FAULT);
			return;
		}


		/*
		 * Parse the time recovery message, and keep the info
		 * to print the pretty billboards.
		 */
		if ((cp = mx4200_parse_t(peer)) != NULL) {
			mx4200_debug(peer, "mx4200_receive: time: %s\n", cp);
			refclock_report(peer, CEVNT_BADREPLY);
			return;
		}

		/*
		 * Add the new sample to a median filter.
		 */
		if (!refclock_process(pp)) {
			mx4200_debug(peer,"mx4200_receive: offset: %.6f\n",
			    pp->offset);
			refclock_report(peer, CEVNT_BADTIME);
			return;
		}

		/*
		 * The clock will blurt a timecode every second but we only
		 * want one when polled.  If we havn't been polled, bail out.
		 */
		if (!up->polled)
			return;

		/*
		 * Return offset and dispersion to control module.  We use
		 * lastrec as both the reference time and receive time in
		 * order to avoid being cute, like setting the reference time
		 * later than the receive time, which may cause a paranoid
		 * protocol module to chuck out the data.
		 */
		mx4200_debug(peer, "mx4200_receive: process time: ");
		mx4200_debug(peer, "%4d-%03d %02d:%02d:%02d at %s, %.6f\n",
		    pp->year, pp->day, pp->hour, pp->minute, pp->second,
		    prettydate(&pp->lastrec), pp->offset);
		pp->lastref = pp->lastrec;
		refclock_receive(peer);

		/*
		 * We have succeeded in answering the poll.
		 * Turn off the flag and return
		 */
		up->polled = 0;
		break;

	/*
	 * Ignore all other sentence types
	 */
	default:
		break;

	} /* switch (sentence_type) */

	return;
}


/*
 * Parse a mx4200 time recovery message. Returns a string if error.
 *
 * A typical message looks like this.  Checksum has already been stripped.
 *
 *    $PMVXG,830,T,YYYY,MM,DD,HH:MM:SS,U,S,FFFFFF,PPPPP,BBBBBB,LL
 *
 *	Field	Field Contents
 *	-----	--------------
 *		Block Label: $PMVXG
 *		Sentence Type: 830=Time Recovery Results
 *			This sentence is output approximately 1 second
 *			preceding the 1PPS output.  It indicates the
 *			exact time of the next pulse, whether or not the
 *			time mark will be valid (based on operator-specified
 *			error tolerance), the time to which the pulse is
 *			synchronized, the receiver operating mode,
 *			and the time error of the *last* 1PPS output.
 *	1  char Time Mark Valid: T=Valid, F=Not Valid
 *	2  int  Year: 1993-
 *	3  int  Month of Year: 1-12
 *	4  int  Day of Month: 1-31
 *	5  int  Time of Day: HH:MM:SS
 *	6  char Time Synchronization: U=UTC, G=GPS
 *	7  char Time Recovery Mode: D=Dynamic, S=Static,
 *			K=Known Position, N=No Time Recovery
 *	8  int  Oscillator Offset: The filter's estimate of the oscillator
 *			frequency error, in parts per billion (ppb).
 *	9  int  Time Mark Error: The computed error of the *last* pulse
 *			output, in nanoseconds.
 *	10 int  User Time Bias: Operator specified bias, in nanoseconds
 *	11 int  Leap Second Flag: Indicates that a leap second will
 *			occur.  This value is usually zero, except during
 *			the week prior to the leap second occurrence, when
 *			this value will be set to +1 or -1.  A value of
 *			+1 indicates that GPS time will be 1 second
 *			further ahead of UTC time.
 *
 */
static char *
mx4200_parse_t(
	struct peer *peer
	)
{
	struct refclockproc *pp;
	struct mx4200unit *up;
	char   time_mark_valid, time_sync, op_mode;
	int    sentence_type, valid;
	int    year, day_of_year, month, day_of_month;
	int    hour, minute, second, leapsec;
	int    oscillator_offset, time_mark_error, time_bias;

	pp = peer->procptr;
	up = (struct mx4200unit *)pp->unitptr;

	leapsec = 0;  /* Not all receivers output leap second warnings (!) */
	sscanf(pp->a_lastcode,
		"$PMVXG,%d,%c,%d,%d,%d,%d:%d:%d,%c,%c,%d,%d,%d,%d",
		&sentence_type, &time_mark_valid, &year, &month, &day_of_month,
		&hour, &minute, &second, &time_sync, &op_mode,
		&oscillator_offset, &time_mark_error, &time_bias, &leapsec);

	if (sentence_type != PMVXG_D_TRECOVOUT)
		return ("wrong rec-type");

	switch (time_mark_valid) {
		case 'T':
			valid = 1;
			break;
		case 'F':
			valid = 0;
			break;
		default:
			return ("bad pulse-valid");
	}

	switch (time_sync) {
		case 'G':
			return ("synchronized to GPS; should be UTC");
		case 'U':
			break; /* UTC -> ok */
		default:
			return ("not synchronized to UTC");
	}

	/*
	 * Check for insane time (allow for possible leap seconds)
	 */
	if (second > 60 || minute > 59 || hour > 23 ||
	    second <  0 || minute <  0 || hour <  0) {
		mx4200_debug(peer,
		    "mx4200_parse_t: bad time %02d:%02d:%02d",
		    hour, minute, second);
		if (leapsec != 0)
			mx4200_debug(peer, " (leap %+d\n)", leapsec);
		mx4200_debug(peer, "\n");
		refclock_report(peer, CEVNT_BADTIME);
		return ("bad time");
	}
	if ( second == 60 ) {
		msyslog(LOG_DEBUG,
		    "mx4200: leap second! %02d:%02d:%02d",
		    hour, minute, second);
	}

	/*
	 * Check for insane date
	 * (Certainly can't be any year before this code was last altered!)
	 */
	if (day_of_month > 31 || month > 12 ||
	    day_of_month <  1 || month <  1 || year < YEAR_LAST_MODIFIED) {
		mx4200_debug(peer,
		    "mx4200_parse_t: bad date (%4d-%02d-%02d)\n",
		    year, month, day_of_month);
		refclock_report(peer, CEVNT_BADDATE);
		return ("bad date");
	}

	/*
	 * Silly Hack for MX4200:
	 * ASCII message is for *next* 1PPS signal, but we have the
	 * timestamp for the *last* 1PPS signal.  So we have to subtract
	 * a second.  Discard if we are on a month boundary to avoid
	 * possible leap seconds and leap days.
	 */
	second--;
	if (second < 0) {
		second = 59;
		minute--;
		if (minute < 0) {
			minute = 59;
			hour--;
			if (hour < 0) {
				hour = 23;
				day_of_month--;
				if (day_of_month < 1) {
					return ("sorry, month boundary");
				}
			}
		}
	}

	/*
	 * Calculate Julian date
	 */
	if (!(day_of_year = mx4200_jday(year, month, day_of_month))) {
		mx4200_debug(peer,
		    "mx4200_parse_t: bad julian date %d (%4d-%02d-%02d)\n",
		    day_of_year, year, month, day_of_month);
		refclock_report(peer, CEVNT_BADDATE);
		return("invalid julian date");
	}

	/*
	 * Setup leap second indicator
	 */
	switch (leapsec) {
		case 0:
			pp->leap = LEAP_NOWARNING;
			break;
		case 1:
			pp->leap = LEAP_ADDSECOND;
			break;
		case -1:
			pp->leap = LEAP_DELSECOND;
			break;
		default:
			pp->leap = LEAP_NOTINSYNC;
	}

	/*
	 * Any change to the leap second warning status?
	 */
	if (leapsec != up->last_leap ) {
		msyslog(LOG_DEBUG,
		    "mx4200: leap second warning: %d to %d (%d)",
		    up->last_leap, leapsec, pp->leap);
	}
	up->last_leap = leapsec;

	/*
	 * Copy time data for billboard monitoring.
	 */

	pp->year   = year;
	pp->day    = day_of_year;
	pp->hour   = hour;
	pp->minute = minute;