/*

 * refclock_fg - clock driver for the Forum Graphic GPS datating station

 */

#ifdef HAVE_CONFIG_H

# include <config.h>

#endif

#if defined(REFCLOCK) && defined(CLOCK_FG)

#include "ntpd.h"

#include "ntp_io.h"

#include "ntp_refclock.h"

#include "ntp_calendar.h"

#include "ntp_stdlib.h"

/*

 * This driver supports the Forum Graphic GPS dating station.

 * More information about FG GPS is available on http://www.forumgraphic.com

 * Contact das@amt.ru for any question about this driver.

 */

/*

 * Interface definitions

 */

#define DEVICE    "/dev/fgclock%d"

#define PRECISION (-10)  /* precision assumed (about 1 ms) */

#define REFID   "GPS"

#define DESCRIPTION "Forum Graphic GPS dating station"

#define LENFG   26  /* timecode length */

#define SPEED232        B9600   /* uart speed (9600 baud) */

/*

 * Function prototypes

 */

static  int   fg_init   (int);

static  int   fg_start  (int, struct peer *);

static  void  fg_shutdown (int, struct peer *);

static  void  fg_poll   (int, struct peer *);

static  void  fg_receive  (struct recvbuf *);

/* 

 * Forum Graphic unit control structure

 */

struct fgunit {

  int pollnum;  /* Use peer.poll instead? */

  int status;   /* Hug to check status information on GPS */

  int y2kwarn;  /* Y2K bug */

};

/* 

 * Queries definition

 */

static char fginit[] = { 0x10, 0x48, 0x10, 0x0D, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0, 0, 0, 0, 0, 0, 0, 0, 0 };

static char fgdate[] = { 0x10, 0x44, 0x10, 0x0D, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,

0, 0, 0, 0, 0, 0, 0, 0, 0 };

/*

 * Transfer vector

 */

struct  refclock refclock_fg = {

  fg_start,   /* start up driver */

  fg_shutdown,    /* shut down driver */

  fg_poll,    /* transmit poll message */

  noentry,    /* not used */

  noentry,    /* initialize driver (not used) */

  noentry,    /* not used */

  NOFLAGS     /* not used */

};

/*

 * fg_init - Initialization of FG GPS.

 */

static int

fg_init(

  int fd

  )

{

  if (write(fd, fginit, LENFG) != LENFG)

    return 0;

  return 1;

}

/*

 * fg_start - open the device and initialize data for processing

 */

static int

fg_start(

  int unit,

  struct peer *peer

  )

{

  struct refclockproc *pp;

  struct fgunit *up;

  int fd;

  char device[20];

  /*

   * Open device file for reading.

   */

  snprintf(device, sizeof(device), DEVICE, unit);

  DPRINTF(1, ("starting FG with device %s\n",device));

  fd = refclock_open(device, SPEED232, LDISC_CLK);

  if (fd <= 0)

    return (0);

  /*

   * Allocate and initialize unit structure

   */

  up = emalloc(sizeof(struct fgunit));

  memset(up, 0, sizeof(struct fgunit));

  pp = peer->procptr;

  pp->unitptr = up;

  pp->io.clock_recv = fg_receive;

  pp->io.srcclock = peer;

  pp->io.datalen = 0;

  pp->io.fd = fd;

  if (!io_addclock(&pp->io)) {

    close(fd);

    pp->io.fd = -1;

    return 0;

  }

  /*

   * Initialize miscellaneous variables

   */

  peer->precision = PRECISION;

  pp->clockdesc = DESCRIPTION;

  memcpy(&pp->refid, REFID, 3);

  up->pollnum = 0;

  /* 

   * Setup dating station to use GPS receiver.

   * GPS receiver should work before this operation.

   */

  if(!fg_init(pp->io.fd))

    refclock_report(peer, CEVNT_FAULT);

  return (1);

}

/*

 * fg_shutdown - shut down the clock

 */

static void

fg_shutdown(

  int unit,

  struct peer *peer

  )

{

  struct refclockproc *pp;

  struct fgunit *up;

  pp = peer->procptr;

  up = pp->unitptr;

  if (pp->io.fd != -1)

    io_closeclock(&pp->io);

  if (up != NULL)

    free(up);

}

/*

 * fg_poll - called by the transmit procedure

 */

static void

fg_poll(

  int unit,

  struct peer *peer

  )

{

  struct refclockproc *pp;

  pp = peer->procptr;

  /*

   * Time to poll the clock. The FG clock responds to a

   * "<DLE>D<DLE><CR>" by returning a timecode in the format specified

   * above. If nothing is heard from the clock for two polls,

   * declare a timeout and keep going.

   */

  if (write(pp->io.fd, fgdate, LENFG) != LENFG)

    refclock_report(peer, CEVNT_FAULT);

  else

    pp->polls++;

  /*

  if (pp->coderecv == pp->codeproc) {

    refclock_report(peer, CEVNT_TIMEOUT);

    return;

  }

  */

  record_clock_stats(&peer->srcadr, pp->a_lastcode);

  return;

}

/*

 * fg_receive - receive data from the serial interface

 */

static void

fg_receive(

  struct recvbuf *rbufp

  )

{

  struct refclockproc *pp;

  struct fgunit *up;

  struct peer *peer;

  char *bpt;

  /*

   * Initialize pointers and read the timecode and timestamp

   * We can't use gtlin function because we need bynary data in buf */

  peer = rbufp->recv_peer;

  pp = peer->procptr;

  up = pp->unitptr;

  /*

   * Below hug to implement receiving of status information

   */

  if(!up->pollnum) {

    up->pollnum++;

    return;

  }

  if (rbufp->recv_length < (LENFG - 2)) {

    refclock_report(peer, CEVNT_BADREPLY);

    return; /* The reply is invalid discard it. */

  }

  /* Below I trying to find a correct reply in buffer.

   * Sometime GPS reply located in the beginnig of buffer,

   * sometime you can find it with some offset.

   */

  bpt = (char *)rbufp->recv_space.X_recv_buffer;

  while (*bpt != '\x10')

    bpt++;

#define BP2(x) ( bpt[x] & 15 )

#define BP1(x) (( bpt[x] & 240 ) >> 4)

  pp->year = BP1(2) * 10 + BP2(2);

  if (pp->year == 94) {

    refclock_report(peer, CEVNT_BADREPLY);

    if (!fg_init(pp->io.fd))

      refclock_report(peer, CEVNT_FAULT);

    return;

     /* GPS is just powered up. The date is invalid -

     discarding it. Initilize GPS one more time */

    /* Sorry - this driver will broken in 2094 ;) */

  } 

  if (pp->year < 99)

    pp->year += 100;

  pp->year +=  1900;

  pp->day = 100 * BP2(3) + 10 * BP1(4) + BP2(4);

/*

   After Jan, 10 2000 Forum Graphic GPS receiver had a very strange

   benahour. It doubles day number for an hours in replys after 10:10:10 UTC

   and doubles min every hour at HH:10:ss for a minute.

   Hope it is a problem of my unit only and not a Y2K problem of FG GPS. 

   Below small code to avoid such situation.

*/

  if (up->y2kwarn > 10)

    pp->hour = BP1(6)*10 + BP2(6);

  else

    pp->hour = BP1(5)*10 + BP2(5);

  if ((up->y2kwarn > 10) && (pp->hour == 10)) {

    pp->minute = BP1(7)*10 + BP2(7);

    pp->second = BP1(8)*10 + BP2(8);

    pp->nsec = (BP1(9)*10 + BP2(9)) * 1000000;

    pp->nsec += BP1(10) * 1000;

  } else {

    pp->hour = BP1(5)*10 + BP2(5);

    pp->minute = BP1(6)*10 + BP2(6);

    pp->second = BP1(7)*10 + BP2(7);

    pp->nsec = (BP1(8)*10 + BP2(8)) * 1000000;

    pp->nsec += BP1(9) * 1000;

  }

  if ((pp->hour == 10) && (pp->minute == 10)) {

    up->y2kwarn++;

  }

  snprintf(pp->a_lastcode, sizeof(pp->a_lastcode),

     "%d %d %d %d %d", pp->year, pp->day, pp->hour,

     pp->minute, pp->second);

  pp->lencode = strlen(pp->a_lastcode);

  /*get_systime(&pp->lastrec);*/

#ifdef DEBUG

  if (debug)

    printf("fg: time is %04d/%03d %02d:%02d:%02d UTC\n",

           pp->year, pp->day, pp->hour, pp->minute, pp->second);

#endif

  pp->disp =  (10e-6);

  pp->lastrec = rbufp->recv_time; /* Is it better than get_systime()? */

  /* 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);

  pp->lastref = pp->lastrec;

  refclock_receive(peer);

  return;

}

#else

int refclock_fg_bs;

#endif /* REFCLOCK */