path: root/driver_sirf.c

/* $Id$ */
/*
 * This is the gpsd driver for SiRF GPSes operating in binary mode.
 * It also handles uBlox, a SiRF derivative.
 *
 * The advantage: Reports climb/sink rate (raw-mode clients won't see this).
 * The disadvantages: Doesn't return PDOP or VDOP, just HDOP.
 *
 * Chris Kuethe, our SiRF expert, tells us:
 * 
 * "I don't see any indication in any of my material that PDOP, GDOP
 * or VDOP are output. There are quantities called Estimated
 * {Horizontal Position, Vertical Position, Time, Horizonal Velocity}
 * Error, but those are apparently only valid when SiRFDRive is
 * active."
 *
 * "(SiRFdrive is their Dead Reckoning augmented firmware. It
 * allows you to feed odometer ticks, gyro and possibly 
 * accelerometer inputs to the chip to allow it to continue 
 * to navigate in the absence of satellite information, and 
 * to improve fixes when you do have satellites.)"
 *
 * "[When we need RINEX data, we can get it from] SiRF Message #5.
 *  If it's no longer implemented on your receiver, messages
 * 7, 28, 29 and 30 will give you the same information."
 */

#include <sys/types.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <ctype.h>
#ifndef S_SPLINT_S
#include <unistd.h>
#endif /* S_SPLINT_S */
#include <time.h>
#include <stdio.h>

#include "gpsd_config.h"
#include "gpsd.h"
#include "bits.h"
#if defined(SIRF_ENABLE) && defined(BINARY_ENABLE)

#define HI(n)		((n) >> 8)
#define LO(n)		((n) & 0xff)

#ifdef ALLOW_RECONFIGURE
/*@ +charint @*/
static unsigned char enablesubframe[] = {0xa0, 0xa2, 0x00, 0x19,
				 0x80, 0x00, 0x00, 0x00,
				 0x00, 0x00, 0x00, 0x00,
				 0x00, 0x00, 0x00, 0x00,
				 0x00, 0x00, 0x00, 0x00,
				 0x00, 0x00, 0x00, 0x00,
				 0x00, 0x00, 0x00, 0x0C,
				 0x10,
				 0x00, 0x00, 0xb0, 0xb3};

static unsigned char disablesubframe[] = {0xa0, 0xa2, 0x00, 0x19,
				  0x80, 0x00, 0x00, 0x00,
				  0x00, 0x00, 0x00, 0x00,
				  0x00, 0x00, 0x00, 0x00,
				  0x00, 0x00, 0x00, 0x00,
				  0x00, 0x00, 0x00, 0x00,
				  0x00, 0x00, 0x00, 0x0C,
				  0x00,
				  0x00, 0x00, 0xb0, 0xb3};

static unsigned char modecontrol[] = {0xa0, 0xa2, 0x00, 0x0e,
			      0x88,
			      0x00, 0x00,	/* pad bytes */
			      0x00,		/* degraded mode off */
			      0x00, 0x00,	/* pad bytes */
			      0x00, 0x00,	/* altitude */
			      0x00,		/* altitude hold auto */
			      0x00,		/* use last computed alt */
			      0x00,		/* reserved */
			      0x00,		/* disable degraded mode */
			      0x00,		/* disable dead reckoning */
			      0x01,		/* enable track smoothing */
			      0x00, 0x00, 0xb0, 0xb3};

static unsigned char enablemid52[] = {
	    0xa0, 0xa2, 0x00, 0x08,
	    0xa6, 0x00, 0x34, 0x01, 0x00, 0x00, 0x00, 0x00,
	    0x00, 0xdb, 0xb0, 0xb3};
/*@ -charint @*/
#endif /* ALLOW_RECONFIGURE */


static gps_mask_t sirf_msg_debug(unsigned char *, size_t );
static gps_mask_t sirf_msg_errors(unsigned char *, size_t );

static gps_mask_t sirf_msg_navdata(struct gps_device_t *, unsigned char *, size_t);
static gps_mask_t sirf_msg_svinfo(struct gps_device_t *, unsigned char *, size_t);
static gps_mask_t sirf_msg_navsol(struct gps_device_t *, unsigned char *, size_t);
#ifdef ALLOW_RECONFIGURE
static gps_mask_t sirf_msg_sysparam(struct gps_device_t *, unsigned char *, size_t);
static gps_mask_t sirf_msg_swversion(struct gps_device_t *, unsigned char *, size_t);
#endif /* ALLOW_RECONFIGURE */
static gps_mask_t sirf_msg_ublox(struct gps_device_t *, unsigned char *, size_t );
static gps_mask_t sirf_msg_ppstime(struct gps_device_t *, unsigned char *, size_t );


static bool sirf_write(int fd, unsigned char *msg) {
   unsigned int       crc;
   size_t    i, len;
   bool      ok;

   len = (size_t)((msg[2] << 8) | msg[3]);

   /* calculate CRC */
   crc = 0;
   for (i = 0; i < len; i++)
	crc += (int)msg[4 + i];
   crc &= 0x7fff;

   /* enter CRC after payload */
   msg[len + 4] = (unsigned char)((crc & 0xff00) >> 8);
   msg[len + 5] = (unsigned char)( crc & 0x00ff);

   gpsd_report(LOG_IO, "Writing SiRF control type %02x:%s\n", msg[4],
       gpsd_hexdump_wrapper(msg, len+8, LOG_IO));
   ok = (write(fd, msg, len+8) == (ssize_t)(len+8));
   (void)tcdrain(fd);
   return(ok);
}

#ifdef ALLOW_CONTROLSEND
static ssize_t sirf_control_send(struct gps_device_t *session, char *msg, size_t len) {
    /*@ +charint +matchanyintegral -initallelements -mayaliasunique @*/
    session->msgbuf[0] = 0xa0;
    session->msgbuf[1] = 0xa2;
    session->msgbuf[2] = (len >> 8) & 0xff;
    session->msgbuf[3] = len & 0xff;
    memcpy(session->msgbuf+4, msg, len);
    session->msgbuf[len + 6] = 0xb0;
    session->msgbuf[len + 7] = 0xb3;
    session->msgbuflen = len + 8;

    return sirf_write(session->gpsdata.gps_fd,
		      (unsigned char *)session->msgbuf) ? (int)session->msgbuflen : -1;
    /*@ -charint -matchanyintegral +initallelements +mayaliasunique @*/
}
#endif /* ALLOW_CONTROLSEND */

#ifdef ALLOW_RECONFIGURE
static bool sirf_speed(int ttyfd, speed_t speed, char parity, int stopbits)
/* change speed in binary mode */
{
    /*@ +charint @*/
   static unsigned char msg[] = {0xa0, 0xa2, 0x00, 0x09,
		     0x86,			/* byte 4: main serial port */
		     0x00, 0x00, 0x12, 0xc0,	/* bytes 5-8: 4800 bps */
		     0x08,			/* byte  9: 8 data bits */
		     0x01,			/* byte 10: 1 stop bit */
		     0x00,			/* byte 11: no parity */
		     0x00,			/* byte 12: reserved pad */
		     0x00, 0x00, 0xb0, 0xb3};
    /*@ -charint @*/

    switch (parity) {
    case 'E':
    case 2:
	parity = (char)2;
	break;
    case 'O':
    case 1:
	parity = (char)1;
	break;
    case 'N':
    case 0:
    default:
	parity = (char)0;
	break;
    }
    msg[7] = (unsigned char)HI(speed);
    msg[8] = (unsigned char)LO(speed);
    msg[10] = (unsigned char)stopbits;
    msg[11] = (unsigned char)parity;
    return (sirf_write(ttyfd, msg));
}

static bool sirf_to_nmea(int ttyfd, speed_t speed)
/* switch from binary to NMEA at specified baud */
{
    /*@ +charint @*/
   static unsigned char msg[] = {0xa0, 0xa2, 0x00, 0x18,
		     0x81, 0x02,
		     0x01, 0x01, /* GGA */
		     0x00, 0x00, /* suppress GLL */
		     0x01, 0x01, /* GSA */
		     0x05, 0x01, /* GSV */
		     0x01, 0x01, /* RMC */
		     0x00, 0x00, /* suppress VTG */
		     0x00, 0x01, 0x00, 0x01,
		     0x00, 0x01, 0x00, 0x01,
		     0x12, 0xc0, /* 4800 bps */
		     0x00, 0x00, 0xb0, 0xb3};
   /*@ -charint @*/

   msg[26] = (unsigned char)HI(speed);
   msg[27] = (unsigned char)LO(speed);
   return (sirf_write(ttyfd, msg));
}

static void sirfbin_mode(struct gps_device_t *session, int mode)
{
    if (mode == MODE_NMEA) {
	(void)sirf_to_nmea(session->gpsdata.gps_fd,session->gpsdata.dev.baudrate);
    } else {
	session->back_to_nmea = false;
    }
}
#endif /* ALLOW_RECONFIGURE */

static ssize_t sirf_get(struct gps_device_t *session)
{
    ssize_t len = generic_get(session);

    if (session->packet.type == SIRF_PACKET) {
	session->gpsdata.dev.driver_mode = MODE_BINARY;
    } else if (session->packet.type == NMEA_PACKET) {
	session->gpsdata.dev.driver_mode = MODE_NMEA;
	(void)gpsd_switch_driver(session, "Generic NMEA");
    } else {
	/* should never happen */
	gpsd_report(LOG_PROG, "Unexpected packet type %d\n", 
		    session->packet.type);
	(void)gpsd_switch_driver(session, "Generic NMEA");
    }

    return len;
}

static gps_mask_t sirf_msg_debug(unsigned char *buf, size_t len)
{
    char msgbuf[MAX_PACKET_LENGTH*3 + 2];
    int i;

    bzero(msgbuf, (int)sizeof(msgbuf));

    /*@ +charint @*/
    if (0xe1 == buf[0]) {		/* Development statistics messages */
	for (i = 2; i < (int)len; i++)
		(void)snprintf(msgbuf+strlen(msgbuf),
			       sizeof(msgbuf)-strlen(msgbuf),
			       "%c", buf[i]^0xff);
	gpsd_report(LOG_PROG, "DEV 0xe1: %s\n", msgbuf);
    } else if (0xff == (unsigned char)buf[0]) {		/* Debug messages */
	for (i = 1; i < (int)len; i++)
	    if (isprint(buf[i]))
		(void)snprintf(msgbuf+strlen(msgbuf),
			       sizeof(msgbuf)-strlen(msgbuf),
			       "%c", buf[i]);
	    else
		(void)snprintf(msgbuf+strlen(msgbuf),
			       sizeof(msgbuf)-strlen(msgbuf),
			       "\\x%02x", (unsigned int)buf[i]);
	gpsd_report(LOG_PROG, "DBG 0xff: %s\n", msgbuf);
    }
    /*@ -charint @*/
    return 0;
}

static gps_mask_t sirf_msg_errors(unsigned char *buf, size_t len UNUSED)
{
    switch (getbeuw(buf, 1)) {
    case 2:
	gpsd_report(LOG_PROG, "EID 0x0a type 2: Subframe %u error on PRN %u\n", getbeul(buf, 9), getbeul(buf, 5));
	break;

    case 4107:
	gpsd_report(LOG_PROG, "EID 0x0a type 4107: neither KF nor LSQ fix.\n");
	break;

    default:
	gpsd_report(LOG_PROG, "EID 0x0a: Error ID type %d\n", getbeuw(buf, 1));
	break;
    }
    return 0;
}

#ifdef ALLOW_RECONFIGURE
static gps_mask_t sirf_msg_swversion(struct gps_device_t *session, unsigned char *buf, size_t len)
{
    double fv;

    if (len < 20)
	return 0;

    gpsd_report(LOG_INF, "FV  0x06: Firmware version: %s\n", buf+1);
    (void)strlcpy(session->subtype, (char *)buf+1, sizeof(session->subtype));
    fv = atof((char *)(buf+1));
    if (fv < 231) {
	session->driver.sirf.driverstate |= SIRF_LT_231;
	if (fv > 200)
	    sirfbin_mode(session, 0);
    } else if (fv < 232) {
	session->driver.sirf.driverstate |= SIRF_EQ_231;
    } else {
	gpsd_report(LOG_PROG, "Enabling PPS message...\n");
	(void)sirf_write(session->gpsdata.gps_fd, enablemid52);
	session->driver.sirf.driverstate |= SIRF_GE_232;
	session->context->valid |= LEAP_SECOND_VALID;
    }
    if (strstr((char *)(buf+1), "ES"))
	gpsd_report(LOG_INF, "Firmware has XTrac capability\n");
    gpsd_report(LOG_PROG, "Driver state flags are: %0x\n", session->driver.sirf.driverstate);
#ifdef NTPSHM_ENABLE
    session->driver.sirf.time_seen = 0;
#endif /* NTPSHM_ENABLE */
    if (session->gpsdata.dev.baudrate >= 38400){
	gpsd_report(LOG_PROG, "Enabling subframe transmission...\n");
	(void)sirf_write(session->gpsdata.gps_fd, enablesubframe);
    }
    return DEVICEID_SET;
}
#endif /* ALLOW_RECONFIGURE */

static gps_mask_t sirf_msg_navdata(struct gps_device_t *session, unsigned char *buf, size_t len)
{
    unsigned int i, words[10], chan, svid;

    if (len != 43)
	return 0;

    chan = (unsigned int)getub(buf, 1);
    svid = (unsigned int)getub(buf, 2);
    words[0] = ((unsigned int)getbeul(buf, 3) & 0x3fffffff) >> 6;
    words[1] = ((unsigned int)getbeul(buf, 7) & 0x3fffffff) >> 6;
    words[2] = ((unsigned int)getbeul(buf, 11) & 0x3fffffff) >> 6;
    words[3] = ((unsigned int)getbeul(buf, 15) & 0x3fffffff) >> 6;
    words[4] = ((unsigned int)getbeul(buf, 19) & 0x3fffffff) >> 6;
    words[5] = ((unsigned int)getbeul(buf, 23) & 0x3fffffff) >> 6;
    words[6] = ((unsigned int)getbeul(buf, 27) & 0x3fffffff) >> 6;
    words[7] = ((unsigned int)getbeul(buf, 31) & 0x3fffffff) >> 6;
    words[8] = ((unsigned int)getbeul(buf, 35) & 0x3fffffff) >> 6;
    words[9] = ((unsigned int)getbeul(buf, 39) & 0x3fffffff) >> 6;
    gpsd_report(LOG_PROG, "50B 0x08\n");

    words[0] &= 0xff0000;
    if (words[0] != 0x8b0000 && words[0] != 0x740000)
       return ERROR_SET;
    if (words[0] == 0x740000)
	for (i = 1; i < 10; i++)
	    words[i] ^= 0xffffff;
    gpsd_interpret_subframe(session, words);

#ifdef ALLOW_RECONFIGURE
    if (session->gpsdata.dev.baudrate < 38400){
	gpsd_report(LOG_PROG, "Disabling subframe transmission...\n");
	(void)sirf_write(session->gpsdata.gps_fd, disablesubframe);
    }
#endif /* ALLOW_RECONFIGURE */
    return 0;
}

#define SIRF_CHANNELS	12	/* max channels allowed in SiRF format */

static gps_mask_t sirf_msg_svinfo(struct gps_device_t *session, unsigned char *buf, size_t len)
{
    int	st, i, j, cn;

    if (len != 188)
	return 0;

    gpsd_zero_satellites(&session->gpsdata);
    session->gpsdata.sentence_time
	    = gpstime_to_unix(getbesw(buf, 1), getbeul(buf, 3)*1e-2) - session->context->leap_seconds;
    for (i = st = 0; i < SIRF_CHANNELS; i++) {
	int off = 8 + 15 * i;
	bool good;
	session->gpsdata.PRN[st]       = (int)getub(buf, off);
	session->gpsdata.azimuth[st]   = (int)(((unsigned)getub(buf, off+1)*3)/2.0);
	session->gpsdata.elevation[st] = (int)((unsigned)getub(buf, off+2)/2.0);
	cn = 0;
	for (j = 0; j < 10; j++)
	    cn += (int)getub(buf, off+5+j);

	session->gpsdata.ss[st] = (float)(cn/10.0);
	good = session->gpsdata.PRN[st]!=0 &&
	    session->gpsdata.azimuth[st]!=0 &&
	    session->gpsdata.elevation[st]!=0;
#ifdef __UNUSED__
	gpsd_report(LOG_PROG, "PRN=%2d El=%3.2f Az=%3.2f ss=%3d stat=%04x %c\n",
			getub(buf, off),
			getub(buf, off+2)/2.0,
			(getub(buf, off+1)*3)/2.0,
			cn/10,
			getbeuw(buf, off+3),
			good ? '*' : ' ');
#endif /* UNUSED */
	if (good!=0)
	    st += 1;
    }
    session->gpsdata.satellites = st;
#ifdef NTPSHM_ENABLE
    if (st > 3) {
	if ((session->driver.sirf.time_seen & TIME_SEEN_GPS_1)==0)
	    gpsd_report(LOG_PROG, "valid time in message 0x04, seen=0x%02x\n",
		session->driver.sirf.time_seen);
	session->driver.sirf.time_seen |= TIME_SEEN_GPS_1;
	if (session->context->enable_ntpshm && IS_HIGHEST_BIT(session->driver.sirf.time_seen,TIME_SEEN_GPS_1))
	    (void)ntpshm_put(session,session->gpsdata.sentence_time+0.8);
    }
#endif /* NTPSHM_ENABLE */
    /*
     * The freaking brain-dead SiRF chip doesn't obey its own
     * rate-control command for 04, at least at firmware rev. 231, 
     * so we have to do our own rate-limiting here...
     */
    gpsd_report(LOG_PROG, "MTD 0x04: %d satellites\n", st);
    if ((session->driver.sirf.satcounter++ % 5) != 0)
	return 0;
    else
	return TIME_SET | SATELLITE_SET;
}

static gps_mask_t sirf_msg_navsol(struct gps_device_t *session, unsigned char *buf, size_t len)
{
    int i;
    unsigned short navtype;
    gps_mask_t mask = 0;

    if (len != 41)
	return 0;

    session->gpsdata.satellites_used = (int)getub(buf, 28);
    memset(session->gpsdata.used,0,sizeof(session->gpsdata.used));
    for (i = 0; i < SIRF_CHANNELS; i++)
	session->gpsdata.used[i] = (int)getub(buf, 29+i);
    if ((session->driver.sirf.driverstate & (SIRF_GE_232 | UBLOX))==0) {
	/* position/velocity is bytes 1-18 */
	ecef_to_wgs84fix(&session->gpsdata,
	     getbesl(buf, 1)*1.0, getbesl(buf, 5)*1.0, getbesl(buf, 9)*1.0,
	     getbesw(buf, 13)/8.0, getbesw(buf, 15)/8.0, getbesw(buf, 17)/8.0);
	/* fix status is byte 19 */
	navtype = (unsigned short)getub(buf, 19);
	session->gpsdata.status = STATUS_NO_FIX;
	session->gpsdata.fix.mode = MODE_NO_FIX;
	if ((navtype & 0x80) != 0)
	    session->gpsdata.status = STATUS_DGPS_FIX;
	else if ((navtype & 0x07) > 0 && (navtype & 0x07) < 7)
	    session->gpsdata.status = STATUS_FIX;
	if ((navtype & 0x07) == 4 || (navtype & 0x07) == 6)
	    session->gpsdata.fix.mode = MODE_3D;
	else if (session->gpsdata.status != 0)
	    session->gpsdata.fix.mode = MODE_2D;
	if (session->gpsdata.fix.mode == MODE_3D)
	    mask |= ALTITUDE_SET | CLIMB_SET;
	gpsd_report(LOG_PROG, "MND 0x02: Navtype = 0x%0x, Status = %d, mode = %d\n",
	    navtype,session->gpsdata.status,session->gpsdata.fix.mode);
	/* byte 20 is HDOP, see below */
	/* byte 21 is "mode 2", not clear how to interpret that */
	session->gpsdata.fix.time = session->gpsdata.sentence_time =
	    gpstime_to_unix(getbesw(buf, 22), getbeul(buf, 24)*1e-2) -
	    session->context->leap_seconds;
#ifdef NTPSHM_ENABLE
	if (session->gpsdata.fix.mode > MODE_NO_FIX) {
	    if ((session->driver.sirf.time_seen & TIME_SEEN_GPS_2) == 0)
		gpsd_report(LOG_PROG, "valid time in message 0x02, seen=0x%02x\n",
		    session->driver.sirf.time_seen);
		session->driver.sirf.time_seen |= TIME_SEEN_GPS_2;
		if (session->context->enable_ntpshm && IS_HIGHEST_BIT(session->driver.sirf.time_seen,TIME_SEEN_GPS_2))
		    (void)ntpshm_put(session, session->gpsdata.fix.time + 0.8);
	}
#endif /* NTPSHM_ENABLE */
	/* fix quality data */
	clear_dop(&session->gpsdata.dop);
	session->gpsdata.dop.hdop = (double)getub(buf, 20)/5.0;
	mask |= TIME_SET | LATLON_SET | TRACK_SET | SPEED_SET | STATUS_SET | MODE_SET | DOP_SET | USED_SET;
    }
    return mask;
}

#ifdef __UNUSED__
/***************************************************************************
 We've stopped interpreting GND (0x29) for the following reasons:

1) Versions of SiRF firmware still in wide circulation (and likely to be
   so fotr a while) don't report a valid time field, leading to annoying
   twice-per-second jitter in client displays.

2) What we wanted out of this that MND didn't give us was horizontal and 
   vertical error estimates. But we have to do our own error estimation by 
   computing DOPs from the skyview covariance matrix anyway, because we
   want separate epx and epy errors a la NMEA 3.0.

3) The fix-merge logic in gpsd.c is (unavoidably) NMEA-centric and
   thinks multiple sentences in one cycle should be treated as
   incremental updates.  This leads to various silly results when (as
   in GND) a subsequent sentence is (a) intended to be a complete fix
   in itself, and (b) frequently broken.

4) Ignoring this dodgy sentence allows us to go to a nice clean single
   fix update per cycle.

Code left in place in case we need to reverse this decision.

***************************************************************************/
static gps_mask_t sirf_msg_geodetic(struct gps_device_t *session, unsigned char *buf, size_t len)
{
    unsigned short navtype;
    gps_mask_t mask = 0;
    double eph;

    if (len != 91)
	return 0;

    session->gpsdata.sentence_length = 91;
    (void)strlcpy(session->gpsdata.tag, "GND",MAXTAGLEN+1);

    navtype = (unsigned short)getbeuw(buf, 3);
    session->gpsdata.status = STATUS_NO_FIX;
    session->gpsdata.fix.mode = MODE_NO_FIX;
    if (navtype & 0x80)
	session->gpsdata.status = STATUS_DGPS_FIX;
    else if ((navtype & 0x07) > 0 && (navtype & 0x07) < 7)
	session->gpsdata.status = STATUS_FIX;
    session->gpsdata.fix.mode = MODE_NO_FIX;
    if ((navtype & 0x07) == 4 || (navtype & 0x07) == 6)
	session->gpsdata.fix.mode = MODE_3D;
    else if (session->gpsdata.status)
	session->gpsdata.fix.mode = MODE_2D;
    gpsd_report(LOG_PROG, "GND 0x29: Navtype = 0x%0x, Status = %d, mode = %d\n",
	navtype, session->gpsdata.status, session->gpsdata.fix.mode);
    mask |= STATUS_SET | MODE_SET;

    session->gpsdata.fix.latitude = getbesl(buf, 23)*1e-7;
    session->gpsdata.fix.longitude = getbesl(buf, 27)*1e-7;
    if (session->gpsdata.fix.latitude!=0 && session->gpsdata.fix.latitude!=0)
	mask |= LATLON_SET;

    if ((eph =  getbesl(buf, 50)*1e-2) > 0) {
	session->gpsdata.fix.epx = session->gpsdata.fix.epy = eph;
	mask |= HERR_SET;
    }
    if ((session->gpsdata.fix.epv =  getbesl(buf, 54)*1e-2) > 0)
	mask |= VERR_SET;
    if ((session->gpsdata.fix.eps =  getbesw(buf, 62)*1e-2) > 0)
	mask |= SPEEDERR_SET;

    /* HDOP should be available at byte 89, but in 231 it's zero. */
    //session->gpsdata.dop.hdop = (unsigned int)getub(buf, 89) * 0.2;

    if ((session->gpsdata.fix.mode > MODE_NO_FIX) && (session->driver.sirf.driverstate & SIRF_GE_232)) {
	struct tm unpacked_date;
	double subseconds;
	/*
	 * Early versions of the SiRF protocol manual don't document 
	 * this sentence at all.  Some that do incorrectly
	 * describe UTC Day, Hour, and Minute as 2-byte quantities,
	 * not 1-byte. Chris Kuethe, our SiRF expert, tells us:
	 *
	 * "The Geodetic Navigation packet (0x29) was not fully
	 * implemented in firmware prior to version 2.3.2. So for
	 * anyone running 231.000.000 or earlier (including ES,
	 * SiRFDRive, XTrac trains) you won't get UTC time. I don't
	 * know what's broken in firmwares before 2.3.1..."
	 *
	 * To work around the incomplete implementation of this
	 * packet in 231, we used to assume that only the altitude field
	 * from this packet is valid.  But even this doesn't necessarily
	 * seem to be the case.  Instead, we do our own computation 
	 * of geoid separation now.
	 *
	 * UTC is left all zeros in 231 and older firmware versions, 
	 * and misdocumented in version 1.4 of the Protocol Reference.
	 *            Documented:        Real:
	 * UTC year       2               2
	 * UTC month      1               1
	 * UTC day        2               1
	 * UTC hour       2               1
	 * UTC minute     2               1
	 * UTC second     2               2
	 *                11              8
	 *
	 * Documentation of this field was corrected in the 1.6 version
	 * of the protocol manual.
	 */
	unpacked_date.tm_year = (int)getbeuw(buf, 11)-1900;
	unpacked_date.tm_mon = (int)getub(buf, 13)-1;
	unpacked_date.tm_mday = (int)getub(buf, 14);
	unpacked_date.tm_hour = (int)getub(buf, 15);
	unpacked_date.tm_min = (int)getub(buf, 16);
	unpacked_date.tm_sec = 0;
	subseconds = getbeuw(buf, 17)*1e-3;
	/*@ -compdef -unrecog */
	session->gpsdata.fix.time = session->gpsdata.sentence_time =
	    (double)timegm(&unpacked_date)+subseconds;
	/*@ +compdef +unrecog */
	gpsd_report(LOG_PROG, "MID 41 UTC: %lf\n", session->gpsdata.fix.time);
#ifdef NTPSHM_ENABLE
	if (session->gpsdata.fix.mode > MODE_NO_FIX && unpacked_date.tm_year != 0) {
	    if ((session->driver.sirf.time_seen & TIME_SEEN_UTC_1) == 0)
		gpsd_report(LOG_PROG, "valid time in message 0x29, seen=0x%02x\n",
		    session->driver.sirf.time_seen);
		session->driver.sirf.time_seen |= TIME_SEEN_UTC_1;
		if (session->context->enable_ntpshm && IS_HIGHEST_BIT(session->driver.sirf.time_seen,TIME_SEEN_UTC_1))
		    (void)ntpshm_put(session, session->gpsdata.fix.time + 0.8);
	}
#endif /* NTPSHM_ENABLE */
	/* skip 4 bytes of satellite map */
	session->gpsdata.fix.altitude = getbesl(buf, 35)*1e-2;
	/* skip 1 byte of map datum */
	session->gpsdata.fix.speed = getbeuw(buf, 40)*1e-2;
	session->gpsdata.fix.track = getbeuw(buf, 42)*1e-2;
	/* skip 2 bytes of magnetic variation */
	session->gpsdata.fix.climb = getbesw(buf, 46)*1e-2;
	mask |= TIME_SET | SPEED_SET | TRACK_SET;
	if (session->gpsdata.fix.mode == MODE_3D)
	    mask |= ALTITUDE_SET | CLIMB_SET;
    }
    return mask;
}
#endif /* __UNUSED__ */

#ifdef ALLOW_RECONFIGURE
static gps_mask_t sirf_msg_sysparam(struct gps_device_t *session, unsigned char *buf, size_t len)
{

    if (len != 65)
	return 0;

    /* save these to restore them in the revert method */
    session->driver.sirf.nav_parameters_seen = true;
    session->driver.sirf.altitude_hold_mode = getub(buf, 5);
    session->driver.sirf.altitude_hold_source = getub(buf, 6);
    session->driver.sirf.altitude_source_input = getbesw(buf, 7);
    session->driver.sirf.degraded_mode = getub(buf, 9);
    session->driver.sirf.degraded_timeout = getub(buf, 10);
    session->driver.sirf.dr_timeout = getub(buf, 11);
    session->driver.sirf.track_smooth_mode = getub(buf, 12);
    gpsd_report(LOG_PROG, "Setting Navigation Parameters\n");
    (void)sirf_write(session->gpsdata.gps_fd, modecontrol);
    return 0;
}
#endif /* ALLOW_RECONFIGURE */

static gps_mask_t sirf_msg_ublox(struct gps_device_t *session, unsigned char *buf, size_t len UNUSED)
{
    gps_mask_t mask;
    unsigned short navtype;

    if (len != 39)
	return 0;

    /* this packet is only sent by uBlox firmware from version 1.32 */
    mask = LATLON_SET | ALTITUDE_SET | SPEED_SET | TRACK_SET | CLIMB_SET |
	STATUS_SET | MODE_SET | DOP_SET;
    session->gpsdata.fix.latitude = getbesl(buf, 1) * RAD_2_DEG * 1e-8;
    session->gpsdata.fix.longitude = getbesl(buf, 5) * RAD_2_DEG * 1e-8;
    session->gpsdata.separation = wgs84_separation(session->gpsdata.fix.latitude, session->gpsdata.fix.longitude);
    session->gpsdata.fix.altitude = getbesl(buf, 9) * 1e-3 - session->gpsdata.separation;
    session->gpsdata.fix.speed = getbesl(buf, 13) * 1e-3;
    session->gpsdata.fix.climb = getbesl(buf, 17) * 1e-3;
    session->gpsdata.fix.track = getbesl(buf, 21) * RAD_2_DEG * 1e-8;

    navtype = (unsigned short)getub(buf, 25);
    session->gpsdata.status = STATUS_NO_FIX;
    session->gpsdata.fix.mode = MODE_NO_FIX;
    if (navtype & 0x80)
	session->gpsdata.status = STATUS_DGPS_FIX;
    else if ((navtype & 0x07) > 0 && (navtype & 0x07) < 7)
	session->gpsdata.status = STATUS_FIX;
    if ((navtype & 0x07) == 4 || (navtype & 0x07) == 6)
	session->gpsdata.fix.mode = MODE_3D;
    else if (session->gpsdata.status)
	session->gpsdata.fix.mode = MODE_2D;
    gpsd_report(LOG_PROG, "EMND 0x62: Navtype = 0x%0x, Status = %d, mode = %d\n",
	 navtype, session->gpsdata.status, session->gpsdata.fix.mode);

    if (navtype & 0x40) {		/* UTC corrected timestamp? */
	struct tm unpacked_date;
	double subseconds;
	mask |= TIME_SET;
	unpacked_date.tm_year = (int)getbeuw(buf, 26) - 1900;
	unpacked_date.tm_mon = (int)getub(buf, 28) - 1;
	unpacked_date.tm_mday = (int)getub(buf, 29);
	unpacked_date.tm_hour = (int)getub(buf, 30);
	unpacked_date.tm_min = (int)getub(buf, 31);
	unpacked_date.tm_sec = 0;
	subseconds = ((unsigned short)getbeuw(buf, 32))*1e-3;
	/*@ -compdef */
	session->gpsdata.fix.time = session->gpsdata.sentence_time =
	    (double)mkgmtime(&unpacked_date)+subseconds;
	/*@ +compdef */
#ifdef NTPSHM_ENABLE
	if ((session->driver.sirf.time_seen & TIME_SEEN_UTC_2) == 0)
	    gpsd_report(LOG_PROG, "valid time in message 0x62, seen=0x%02x\n",
		session->driver.sirf.time_seen);
	    session->driver.sirf.time_seen |= TIME_SEEN_UTC_2;
	if (session->context->enable_ntpshm && IS_HIGHEST_BIT(session->driver.sirf.time_seen,TIME_SEEN_UTC_2))
	    (void)ntpshm_put(session, session->gpsdata.fix.time + 0.8);
#endif /* NTPSHM_ENABLE */
	session->context->valid |= LEAP_SECOND_VALID;
    }

    clear_dop(&session->gpsdata.dop);
    session->gpsdata.dop.gdop = (int)getub(buf, 34) / 5.0;
    session->gpsdata.dop.pdop = (int)getub(buf, 35) / 5.0;
    session->gpsdata.dop.hdop = (int)getub(buf, 36) / 5.0;
    session->gpsdata.dop.vdop = (int)getub(buf, 37) / 5.0;
    session->gpsdata.dop.tdop = (int)getub(buf, 38) / 5.0;
    session->driver.sirf.driverstate |= UBLOX;
    return mask;
}

static gps_mask_t sirf_msg_ppstime(struct gps_device_t *session, unsigned char *buf, size_t len)
{
    gps_mask_t mask = 0;

    if (len != 19)
	return 0;

    gpsd_report(LOG_PROG, "PPS 0x34: Status = 0x%02x\n", getub(buf, 14));
    if (((int)getub(buf, 14) & 0x07) == 0x07) {	/* valid UTC time? */
	struct tm unpacked_date;
	unpacked_date.tm_hour = (int)getub(buf, 1);
	unpacked_date.tm_min = (int)getub(buf, 2);
	unpacked_date.tm_sec = (int)getub(buf, 3);
	unpacked_date.tm_mday = (int)getub(buf, 4);
	unpacked_date.tm_mon = (int)getub(buf, 5) - 1;
	unpacked_date.tm_year = (int)getbeuw(buf, 6) - 1900;
	/*@ -compdef */
	session->gpsdata.fix.time = session->gpsdata.sentence_time =
	    (double)mkgmtime(&unpacked_date);
	/*@ +compdef */
	session->context->leap_seconds = (int)getbeuw(buf, 8);
	session->context->valid |= LEAP_SECOND_VALID;
#ifdef NTPSHM_ENABLE
	if ((session->driver.sirf.time_seen & TIME_SEEN_UTC_2) == 0)
	    gpsd_report(LOG_PROG, "valid time in message 0x34, seen=0x%02x\n",
		session->driver.sirf.time_seen);
	session->driver.sirf.time_seen |= TIME_SEEN_UTC_2;
	if (session->context->enable_ntpshm && IS_HIGHEST_BIT(session->driver.sirf.time_seen,TIME_SEEN_UTC_2))
	    (void)ntpshm_put(session, session->gpsdata.fix.time + 0.3);
#endif /* NTPSHM_ENABLE */
	mask |= TIME_SET;
    }
    return mask;
}

gps_mask_t sirf_parse(struct gps_device_t *session, unsigned char *buf, size_t len)
{

    if (len == 0)
	return 0;

    buf += 4;
    len -= 8;
    gpsd_report(LOG_RAW, "Raw SiRF packet type 0x%02x length %zd: %s\n",
	buf[0], len, gpsd_hexdump_wrapper(buf, len, LOG_RAW));
    (void)snprintf(session->gpsdata.tag, sizeof(session->gpsdata.tag),
		   "MID%d",(int)buf[0]);

    /* could change if the set of messages we enable does */
    session->cycle_state = CYCLE_END_RELIABLE;
    if (buf[0] == (unsigned char)0x02 || buf[0] == (unsigned char)0x62)
	session->cycle_state |= (CYCLE_START | CYCLE_END);

    switch (buf[0])
    {
    case 0x02:		/* Measure Navigation Data Out */
	return sirf_msg_navsol(session, buf, len);

    case 0x04:		/* Measured tracker data out */
	return sirf_msg_svinfo(session, buf, len);

    case 0x05:		/* Raw Tracker Data Out */
	return 0;

#ifdef ALLOW_RECONFIGURE
    case 0x06:		/* Software Version String */
	return sirf_msg_swversion(session, buf, len);
#endif /* ALLOW_RECONFIGURE */

    case 0x07:		/* Clock Status Data */
	gpsd_report(LOG_PROG, "CLK 0x07\n");
	return 0;

    case 0x08:		/* subframe data -- extract leap-second from this */
	/*
	 * Chris Kuethe says:
	 * "Message 8 is generated as the data is received. It is not
	 * buffered on the chip. So when you enable message 8, you'll
	 * get one subframe every 6 seconds.  Of the data received, the
	 * almanac and ephemeris are buffered and stored, so you can
	 * query them at will. Alas, the time parameters are not
	 * stored, which is really lame, as the UTC-GPS correction
	 * changes 1 second every few years. Maybe."
	 */
	return sirf_msg_navdata(session, buf, len);

    case 0x09:		/* CPU Throughput */
	gpsd_report(LOG_PROG,
		    "THR 0x09: SegStatMax=%.3f, SegStatLat=%3.f, AveTrkTime=%.3f, Last MS=%u\n",
		    (float)getbeuw(buf, 1)/186, (float)getbeuw(buf, 3)/186,
		    (float)getbeuw(buf, 5)/186, getbeuw(buf, 7));
	return 0;

    case 0x0a:		/* Error ID Data */
	return sirf_msg_errors(buf, len);

    case 0x0b:		/* Command Acknowledgement */
	gpsd_report(LOG_PROG, "ACK 0x0b: %02x\n",getub(buf, 1));
	return 0;

    case 0x0c:		/* Command NAcknowledgement */
	gpsd_report(LOG_PROG, "NAK 0x0c: %02x\n",getub(buf, 1));
	return 0;

    case 0x0d:		/* Visible List */
	gpsd_report(LOG_PROG, "VIS 0x0d\n");
	return 0;

    case 0x0e:		/* Almanac Data */
	gpsd_report(LOG_PROG, "ALM  0x0e: %s\n",
	    gpsd_hexdump_wrapper(buf, len, LOG_PROG));
	return 0;

    case 0x0f:		/* Ephemeris Data */
	gpsd_report(LOG_PROG, "EPH  0x0f: %s\n",
	    gpsd_hexdump_wrapper(buf, len, LOG_PROG));
	return 0;

    case 0x11:		/* Differential Corrections */
	gpsd_report(LOG_PROG, "DIFF 0x11: %s\n",
	    gpsd_hexdump_wrapper(buf, len, LOG_PROG));
	return 0;

    case 0x12:		/* OK To Send */
	gpsd_report(LOG_PROG, "OTS 0x12: send indicator = %d\n",getub(buf, 1));
	return 0;

#ifdef ALLOW_RECONFIGURE
    case 0x13:	/* Navigation Parameters */
	return sirf_msg_sysparam(session, buf, len);
#endif /* ALLOW_RECONFIGURE */

    case 0x1b:		/* DGPS status (undocumented) */
	gpsd_report(LOG_PROG, "DGPSF 0x1b %s\n",
	    gpsd_hexdump_wrapper(buf, len, LOG_PROG));
	return 0;

    case 0x1c:		/* Navigation Library Measurement Data */
	gpsd_report(LOG_PROG, "NLMD 0x1c: %s\n",
	    gpsd_hexdump_wrapper(buf, len, LOG_PROG));
	return 0;

    case 0x1d:		/* Navigation Library DGPS Data */
	gpsd_report(LOG_PROG, "NLDG 0x1d: %s\n",
	    gpsd_hexdump_wrapper(buf, len, LOG_PROG));
	return 0;

    case 0x1e:		/* Navigation Library SV State Data */
	gpsd_report(LOG_PROG, "NLSV 0x1e: %s\n",
	    gpsd_hexdump_wrapper(buf, len, LOG_PROG));
	return 0;

    case 0x1f:		/* Navigation Library Initialization Data */
	gpsd_report(LOG_PROG, "NLID 0x1f: %s\n",
	    gpsd_hexdump_wrapper(buf, len, LOG_PROG));
	return 0;

    case 0x29:		/* Geodetic Navigation Information */
	gpsd_report(LOG_PROG, "GND 0x29: %s\n",
	    gpsd_hexdump_wrapper(buf, len, LOG_PROG));
	return 0;

    case 0x32:		/* SBAS corrections */
	return 0;

    case 0x34:		/* PPS Time */
	/*
	 * Carl Carter from SiRF writes: "We do not output on the
	 * second (unless you are using message ID 52).  We make
	 * measurements in the receiver in time with an internal
	 * counter that is not slaved to GPS time, so the measurements
	 * are made at a time that wanders around the second.  Then,
	 * after the measurements are made (all normalized to the same
	 * point in time) we dispatch the navigation software to make
	 * a solution, and that solution comes out some 200 to 300 ms
	 * after the measurement time.  So you may get a message at
	 * 700 ms after the second that uses measurements time tagged
	 * 450 ms after the second.  And if some other task jumps up
	 * and delays things, that message may not come out until 900
	 * ms after the second.  Things can get out of sync to the
	 * point that if you try to resolve the GPS time of our 1 PPS
	 * pulses using the navigation messages, you will find it
	 * impossible to be consistent.  That is why I added message
	 * ID 52 to our system -- it is tied to the creation of the 1
	 * PPS and always comes out right around the top of the
	 * second."
	 */
	return sirf_msg_ppstime(session, buf, len);

    case 0x62:		/* uBlox Extended Measured Navigation Data */
	return sirf_msg_ublox(session, buf, len);

    case 0x80:		/* Initialize Data Source */
	gpsd_report(LOG_PROG, "INIT 0x80: %s\n",
	    gpsd_hexdump_wrapper(buf, len, LOG_PROG));
	return 0;

    case 0xe1:		/* Development statistics messages */
	/* FALLTHROUGH */
    case 0xff:		/* Debug messages */
	(void)sirf_msg_debug(buf, len);
	return 0;

    default:
	gpsd_report(LOG_WARN, "Unknown SiRF packet id %d length %zd: %s\n",
	    buf[0], len, gpsd_hexdump_wrapper(buf, len, LOG_WARN));
	return 0;
    }
}

static gps_mask_t sirfbin_parse_input(struct gps_device_t *session)
{
    gps_mask_t st;

    if (session->packet.type == SIRF_PACKET){
	st = sirf_parse(session, session->packet.outbuffer,
			session->packet.outbuflen);
	session->gpsdata.dev.driver_mode = MODE_BINARY;
	return st;
#ifdef NMEA_ENABLE
    } else if (session->packet.type == NMEA_PACKET) {
	st = nmea_parse((char *)session->packet.outbuffer, session);
	session->gpsdata.dev.driver_mode = MODE_NMEA;
	return st;
#endif /* NMEA_ENABLE */
    } else
	return 0;
}

#ifdef ALLOW_RECONFIGURE
static void sirfbin_event_hook(struct gps_device_t *session, event_t event)
{
    if (event == event_identified || event == event_reactivate) {
	if (session->packet.type == NMEA_PACKET) {
	    gpsd_report(LOG_PROG, "Switching chip mode to SiRF binary.\n");
	    (void)nmea_send(session,
			    "$PSRF100,0,%d,8,1,0", session->gpsdata.dev.baudrate);
	}
	/* do this every time*/
	{
	    /*@ +charint @*/
	    static unsigned char navparams[] = {0xa0, 0xa2, 0x00, 0x02,
						0x98, 0x00,
						0x00, 0x00, 0xb0, 0xb3};
	    static unsigned char dgpscontrol[] = {0xa0, 0xa2, 0x00, 0x07,
						  0x85, 0x01, 0x00, 0x00,
						  0x00, 0x00, 0x00,
						  0x00, 0x00, 0xb0, 0xb3};
	    static unsigned char sbasparams[] = {0xa0, 0xa2, 0x00, 0x06,
						 0xaa, 0x00, 0x01, 0x00,
						 0x00, 0x00,
						 0x00, 0x00, 0xb0, 0xb3};
	    static unsigned char versionprobe[] = {0xa0, 0xa2, 0x00, 0x02,
						   0x84, 0x00,
						   0x00, 0x00, 0xb0, 0xb3};
	    static unsigned char requestecef[] = {0xa0, 0xa2, 0x00, 0x08,
						  0xa6, 0x00, 0x02, 0x01,
						  0x00, 0x00, 0x00, 0x00,
						  0x00, 0x00, 0xb0, 0xb3};
	    static unsigned char requesttracker[] = {0xa0, 0xa2, 0x00, 0x08,
						     0xa6, 0x00, 0x04, 0x03,
						     0x00, 0x00, 0x00, 0x00,
						     0x00, 0x00, 0xb0, 0xb3};
	    /*@ -charint @*/
	    gpsd_report(LOG_PROG, "Requesting periodic ecef reports...\n");
	    (void)sirf_write(session->gpsdata.gps_fd, requestecef);
	    gpsd_report(LOG_PROG, "Requesting periodic tracker reports...\n");
	    (void)sirf_write(session->gpsdata.gps_fd, requesttracker);
	    gpsd_report(LOG_PROG, "Setting DGPS control to use SBAS...\n");
	    (void)sirf_write(session->gpsdata.gps_fd, dgpscontrol);
	    gpsd_report(LOG_PROG, "Setting SBAS to auto/integrity mode...\n");
	    (void)sirf_write(session->gpsdata.gps_fd, sbasparams);
	    gpsd_report(LOG_PROG, "Probing for firmware version...\n");
	    (void)sirf_write(session->gpsdata.gps_fd, versionprobe);
	    gpsd_report(LOG_PROG, "Requesting navigation parameters...\n");
	    (void)sirf_write(session->gpsdata.gps_fd, navparams);
	}
    }
    if (event == event_deactivate) {

	/*@ +charint @*/
	static unsigned char moderevert[] = {0xa0, 0xa2, 0x00, 0x0e,
					     0x88,
					     0x00, 0x00,	/* pad bytes */
					     0x00,		/* degraded mode */
					     0x00, 0x00,	/* pad bytes */
					     0x00, 0x00,	/* altitude source */
					     0x00,		/* altitude hold mode */
					     0x00,		/* use last computed alt */
					     0x00,		/* reserved */
					     0x00,		/* degraded mode timeout */
					     0x00,		/* dead reckoning timeout */
					     0x00,		/* track smoothing */
					     0x00, 0x00, 0xb0, 0xb3};
	/*@ -charint -shiftimplementation @*/
	putbyte(moderevert, 7, session->driver.sirf.degraded_mode);
	putbeword(moderevert, 10, session->driver.sirf.altitude_source_input);
	putbyte(moderevert, 12, session->driver.sirf.altitude_hold_mode);
	putbyte(moderevert, 13, session->driver.sirf.altitude_hold_source);
	putbyte(moderevert, 15, session->driver.sirf.degraded_timeout);
	putbyte(moderevert, 16, session->driver.sirf.dr_timeout);
	putbyte(moderevert, 17, session->driver.sirf.track_smooth_mode);
	/*@ +shiftimplementation @*/
	gpsd_report(LOG_PROG, "Reverting navigation parameters...\n");
	(void)sirf_write(session->gpsdata.gps_fd, moderevert);
    }
}

static bool sirfbin_speed(struct gps_device_t *session, 
			  speed_t speed, char parity, int stopbits)
{
    return sirf_speed(session->gpsdata.gps_fd, speed, parity, stopbits);
}
#endif /* ALLOW_RECONFIGURE */

/* this is everything we export */
const struct gps_type_t sirf_binary =
{
    .type_name      = "SiRF binary",	/* full name of type */
    .packet_type    = SIRF_PACKET,	/* associated lexer packet type */
    .trigger	    = NULL,		/* no trigger */
    .channels       = SIRF_CHANNELS,	/* consumer-grade GPS */
    .probe_detect   = NULL,		/* no probe */
    .get_packet     = sirf_get,		/* be prepared for SiRF or NMEA */
    .parse_packet   = sirfbin_parse_input,/* parse message packets */
    .rtcm_writer    = pass_rtcm,	/* send RTCM data straight */
    .event_hook     = sirfbin_event_hook,/* lifetime event handler */
#ifdef ALLOW_RECONFIGURE
    .speed_switcher = sirfbin_speed,	/* we can change baud rate */
    .mode_switcher  = sirfbin_mode,	/* there's a mode switcher */
    .rate_switcher  = NULL,		/* no sample-rate switcher */
    .min_cycle      = 1,		/* not relevant, no rate switch */
#endif /* ALLOW_RECONFIGURE */
#ifdef ALLOW_CONTROLSEND
    .control_send   = sirf_control_send,/* how to send a control string */
#endif /* ALLOW_CONTROLSEND */
};
#endif /* defined(SIRF_ENABLE) && defined(BINARY_ENABLE) */