/*
 * refclock_as2201 - clock driver for the Austron 2201A GPS
 *	Timing Receiver
 */
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#if defined(REFCLOCK) && defined(CLOCK_AS2201)

#include "ntpd.h"
#include "ntp_io.h"
#include "ntp_refclock.h"
#include "ntp_unixtime.h"
#include "ntp_stdlib.h"

#include <stdio.h>
#include <ctype.h>

/*
 * This driver supports the Austron 2200A/2201A GPS Receiver with
 * Buffered RS-232-C Interface Module. Note that the original 2200/2201
 * receivers will not work reliably with this driver, since the older
 * design cannot accept input commands at any reasonable data rate.
 *
 * The program sends a "*toc\r" to the radio and expects a response of
 * the form "yy:ddd:hh:mm:ss.mmm\r" where yy = year of century, ddd =
 * day of year, hh:mm:ss = second of day and mmm = millisecond of
 * second. Then, it sends statistics commands to the radio and expects
 * a multi-line reply showing the corresponding statistics or other
 * selected data. Statistics commands are sent in order as determined by
 * a vector of commands; these might have to be changed with different
 * radio options. If flag4 of the fudge configuration command is set to
 * 1, the statistics data are written to the clockstats file for later
 * processing.
 *
 * In order for this code to work, the radio must be placed in non-
 * interactive mode using the "off" command and with a single <cr>
 * response using the "term cr" command. The setting of the "echo"
 * and "df" commands does not matter. The radio should select UTC
 * timescale using the "ts utc" command.
 *
 * There are two modes of operation for this driver. The first with
 * default configuration is used with stock kernels and serial-line
 * drivers and works with almost any machine. In this mode the driver
 * assumes the radio captures a timestamp upon receipt of the "*" that
 * begins the driver query. Accuracies in this mode are in the order of
 * a millisecond or two and the receiver can be connected to only one
 * host.
 *
 * The second mode of operation can be used for SunOS kernels that have
 * been modified with the ppsclock streams module included in this
 * distribution. The mode is enabled if flag3 of the fudge configuration
 * command has been set to 1. In this mode a precise timestamp is
 * available using a gadget box and 1-pps signal from the receiver. This
 * improves the accuracy to the order of a few tens of microseconds. In
 * addition, the serial output and 1-pps signal can be bussed to more
 * than one hosts, but only one of them should be connected to the
 * radio input data line. 
 */

/*
 * GPS Definitions
 */
#define SMAX		200	/* statistics buffer length */
#define	DEVICE		"/dev/gps%d" /* device name and unit */
#define	SPEED232	B9600	/* uart speed (9600 baud) */
#define	PRECISION	(-20)	/* precision assumed (about 1 us) */
#define	REFID		"GPS\0"	/* reference ID */
#define	DESCRIPTION	"Austron 2201A GPS Receiver" /* WRU */

#define	LENTOC		19	/* yy:ddd:hh:mm:ss.mmm timecode lngth */

/*
 * AS2201 unit control structure.
 */
struct as2201unit {
	char	*lastptr;	/* statistics buffer pointer */
	char	stats[SMAX];	/* statistics buffer */
	int	linect;		/* count of lines remaining */
	int	index;		/* current statistics command */
};

/*
 * Radio commands to extract statitistics
 *
 * A command consists of an ASCII string terminated by a <cr> (\r). The
 * command list consist of a sequence of commands terminated by a null
 * string ("\0"). One command from the list is sent immediately
 * following each received timecode (*toc\r command) and the ASCII
 * strings received from the radio are saved along with the timecode in
 * the clockstats file. Subsequent commands are sent at each timecode,
 * with the last one in the list followed by the first one. The data
 * received from the radio consist of ASCII strings, each terminated by
 * a <cr> (\r) character. The number of strings for each command is
 * specified as the first line of output as an ASCII-encode number. Note
 * that the ETF command requires the Input Buffer Module and the LORAN
 * commands require the LORAN Assist Module. However, if these modules
 * are not installed, the radio and this driver will continue to operate
 * successfuly, but no data will be captured for these commands.
 */
static char stat_command[][30] = {
	"ITF\r",		/* internal time/frequency */
	"ETF\r",		/* external time/frequency */
	"LORAN ENSEMBLE\r",	/* GPS/LORAN ensemble statistics */
	"LORAN TDATA\r",	/* LORAN signal data */
	"ID;OPT;VER\r",		/* model; options; software version */

	"ITF\r",		/* internal time/frequency */
	"ETF\r",		/* external time/frequency */
	"LORAN ENSEMBLE\r",	/* GPS/LORAN ensemble statistics */
	"TRSTAT\r",		/* satellite tracking status */
	"POS;PPS;PPSOFF\r",	/* position, pps source, offsets */

	"ITF\r",		/* internal time/frequency */
	"ETF\r",		/* external time/frequency */
	"LORAN ENSEMBLE\r",	/* GPS/LORAN ensemble statistics */
	"LORAN TDATA\r",	/* LORAN signal data */
	"UTC\r",			/* UTC leap info */

	"ITF\r",		/* internal time/frequency */
	"ETF\r",		/* external time/frequency */
	"LORAN ENSEMBLE\r",	/* GPS/LORAN ensemble statistics */
	"TRSTAT\r",		/* satellite tracking status */
	"OSC;ET;TEMP\r",	/* osc type; tune volts; oven temp */
	"\0"			/* end of table */
};

/*
 * Function prototypes
 */
static	int	as2201_start	(int, struct peer *);
static	void	as2201_shutdown	(int, struct peer *);
static	void	as2201_receive	(struct recvbuf *);
static	void	as2201_poll	(int, struct peer *);

/*
 * Transfer vector
 */
struct	refclock refclock_as2201 = {
	as2201_start,		/* start up driver */
	as2201_shutdown,	/* shut down driver */
	as2201_poll,		/* transmit poll message */
	noentry,		/* not used (old as2201_control) */
	noentry,		/* initialize driver (not used) */
	noentry,		/* not used (old as2201_buginfo) */
	NOFLAGS			/* not used */
};


/*
 * as2201_start - open the devices and initialize data for processing
 */
static int
as2201_start(
	int unit,
	struct peer *peer
	)
{
	register struct as2201unit *up;
	struct refclockproc *pp;
	int fd;
	char gpsdev[20];

	/*
	 * Open serial port. Use CLK line discipline, if available.
	 */
	snprintf(gpsdev, sizeof(gpsdev), DEVICE, unit);
	fd = refclock_open(gpsdev, SPEED232, LDISC_CLK);
	if (fd <= 0)
		return (0);

	/*
	 * Allocate and initialize unit structure
	 */
	up = emalloc_zero(sizeof(*up));
	pp = peer->procptr;
	pp->io.clock_recv = as2201_receive;
	pp->io.srcclock = peer;
	pp->io.datalen = 0;
	pp->io.fd = fd;
	if (!io_addclock(&pp->io)) {
		close(fd);
		pp->io.fd = -1;
		free(up);
		return (0);
	}
	pp->unitptr = up;

	/*
	 * Initialize miscellaneous variables
	 */
	peer->precision = PRECISION;
	pp->clockdesc = DESCRIPTION;
	memcpy((char *)&pp->refid, REFID, 4);
	up->lastptr = up->stats;
	up->index = 0;
	return (1);
}


/*
 * as2201_shutdown - shut down the clock
 */
static void
as2201_shutdown(
	int unit,
	struct peer *peer
	)
{
	register struct as2201unit *up;
	struct refclockproc *pp;

	pp = peer->procptr;
	up = pp->unitptr;
	if (-1 != pp->io.fd)
		io_closeclock(&pp->io);
	if (NULL != up)
		free(up);
}


/*
 * as2201__receive - receive data from the serial interface
 */
static void
as2201_receive(
	struct recvbuf *rbufp
	)
{
	register struct as2201unit *up;
	struct refclockproc *pp;
	struct peer *peer;
	l_fp trtmp;
	size_t octets;

	/*
	 * Initialize pointers and read the timecode and timestamp.
	 */
	peer = rbufp->recv_peer;
	pp = peer->procptr;
	up = pp->unitptr;
	pp->lencode = refclock_gtlin(rbufp, pp->a_lastcode, BMAX, &trtmp);
#ifdef DEBUG
	if (debug)
	    printf("gps: timecode %d %d %s\n",
		   up->linect, pp->lencode, pp->a_lastcode);
#endif
	if (pp->lencode == 0)
	    return;

	/*
	 * If linect is greater than zero, we must be in the middle of a
	 * statistics operation, so simply tack the received data at the
	 * end of the statistics string. If not, we could either have
	 * just received the timecode itself or a decimal number
	 * indicating the number of following lines of the statistics
	 * reply. In the former case, write the accumulated statistics
	 * data to the clockstats file and continue onward to process
	 * the timecode; in the later case, save the number of lines and
	 * quietly return.
	 */
	if (pp->sloppyclockflag & CLK_FLAG2)
		pp->lastrec = trtmp;
	if (up->linect > 0) {
		up->linect--;
		if ((int)(up->lastptr - up->stats + pp->lencode) > SMAX - 2)
		    return;
		*up->lastptr++ = ' ';
		memcpy(up->lastptr, pp->a_lastcode, 1 + pp->lencode);
		up->lastptr += pp->lencode;
		return;
	} else {
		if (pp->lencode == 1) {
			up->linect = atoi(pp->a_lastcode);
			return;
		} else {
			record_clock_stats(&peer->srcadr, up->stats);
#ifdef DEBUG
			if (debug)
			    printf("gps: stat %s\n", up->stats);
#endif
		}
	}
	up->lastptr = up->stats;
	*up->lastptr = '\0';

	/*
	 * We get down to business, check the timecode format and decode
	 * its contents. If the timecode has invalid length or is not in
	 * proper format, we declare bad format and exit.
	 */
	if (pp->lencode < LENTOC) {
		refclock_report(peer, CEVNT_BADREPLY);
		return;
	}

	/*
	 * Timecode format: "yy:ddd:hh:mm:ss.mmm"
	 */
	if (sscanf(pp->a_lastcode, "%2d:%3d:%2d:%2d:%2d.%3ld", &pp->year,
		   &pp->day, &pp->hour, &pp->minute, &pp->second, &pp->nsec)
	    != 6) {
		refclock_report(peer, CEVNT_BADREPLY);
		return;
	}
	pp->nsec *= 1000000;

	/*
	 * Test for synchronization (this is a temporary crock).
	 */
	if (pp->a_lastcode[2] != ':')
		pp->leap = LEAP_NOTINSYNC;
	else
		pp->leap = LEAP_NOWARNING;

	/*
	 * Process the new sample in the median filter and determine the
	 * timecode timestamp.
	 */
	if (!refclock_process(pp)) {
		refclock_report(peer, CEVNT_BADTIME);
		return;
	}

	/*
	 * If CLK_FLAG4 is set, initialize the statistics buffer and
	 * send the next command. If not, simply write the timecode to
	 * the clockstats file.
	 */
	if ((int)(up->lastptr - up->stats + pp->lencode) > SMAX - 2)
	    return;
	memcpy(up->lastptr, pp->a_lastcode, pp->lencode);
	up->lastptr += pp->lencode;
	if (pp->sloppyclockflag & CLK_FLAG4) {
		octets = strlen(stat_command[up->index]);
		if ((int)(up->lastptr - up->stats + 1 + octets) > SMAX - 2)
		    return;
		*up->lastptr++ = ' ';
		memcpy(up->lastptr, stat_command[up->index], octets);
		up->lastptr += octets - 1;
		*up->lastptr = '\0';
		(void)write(pp->io.fd, stat_command[up->index],
		    strlen(stat_command[up->index]));
		up->index++;
		if (*stat_command[up->index] == '\0')
			up->index = 0;
	}
}


/*
 * as2201_poll - called by the transmit procedure
 *
 * We go to great pains to avoid changing state here, since there may be
 * more than one eavesdropper receiving the same timecode.
 */
static void
as2201_poll(
	int unit,
	struct peer *peer
	)
{
	struct refclockproc *pp;

	/*
	 * Send a "\r*toc\r" to get things going. We go to great pains
	 * to avoid changing state, since there may be more than one
	 * eavesdropper watching the radio.
	 */
	pp = peer->procptr;
	if (write(pp->io.fd, "\r*toc\r", 6) != 6) {
		refclock_report(peer, CEVNT_FAULT);
	} else {
		pp->polls++;
		if (!(pp->sloppyclockflag & CLK_FLAG2))
			get_systime(&pp->lastrec);
	}
        if (pp->coderecv == pp->codeproc) {
                refclock_report(peer, CEVNT_TIMEOUT);
                return;
        }
        refclock_receive(peer);
}

#else
int refclock_as2201_bs;
#endif /* REFCLOCK */