path: root/driver_navcom.c

/* $Id$ */
/*
 * Driver for Navcom receivers using propietary NCT messages, a binary protocol.
 *
 * Vendor website: http://www.navcomtech.com/
 * Technical references: http://www.navcomtech.com/support/docs.cfm
 *
 * Tested with two SF-2040G models
 *
 * At this stage, this driver implements the following commands:
 *
 * 0x20: Data Request (tell the unit which responses you want)
 * 0x3f: LED Configuration (controls the front panel LEDs -- for testing)
 * 0x1c: Test Support Block (again, blinks the front panel lights)
 *
 * and it understands the following responses:
 *
 * 0x06: Acknowledgement (without error)
 * 0x15: Negative Acknowledge
 * 0x86: Channel Status
 * 0xae: Identification Block
 * 0xb0: Raw Meas. Data Block
 * 0xb1: PVT Block
 * 0xb5: Pseudorange Noise Statistics
 * 0xd3: LBM DSP Status Block
 * 0xef: Clock Drift and Offset
 *
 * FIXME - I'm not too sure of the way I have computed the vertical positional error
 *	 I have used FOM as a scaling factor for VDOP, thusly VRMS = FOM/HDOP*VDOP
 *
 * By Diego Berge. Contact via web form at http://www.navlost.eu/contact
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <ctype.h>
#include <unistd.h>
#include <time.h>
#include <sys/types.h>
#include <inttypes.h>
#include <stdio.h>
#include "gpsd_config.h"
#include "gpsd.h"

#if defined(NAVCOM_ENABLE) && defined(BINARY_ENABLE)
#include "bits.h"

/* Have data which is 24 bits long */
#define getlesl24(buf,off)  (int32_t)(((u_int32_t)getub((buf), (off)+2)<<24 | (u_int32_t)getub((buf), (off)+1)<<16 | (u_int32_t)getub((buf), (off))<<8)>>8)
#define getleul24(buf,off) (u_int32_t)(((u_int32_t)getub((buf), (off)+2)<<24 | (u_int32_t)getub((buf), (off)+1)<<16 | (u_int32_t)getub((buf), (off))<<8)>>8)

/* And just to be difficult, Navcom is little endian but the GPS data stream
   is big endian.  Some messages contain raw GPS data */
#define getlesw_be(buf, off)	(int16_t)((((u_int16_t)getub(buf, (off)) << 8) \
				    | (u_int16_t)getub(buf, (off)+1)))
#define getleuw_be(buf, off)	(u_int16_t)((((u_int16_t)getub(buf, (off)) << 8) \
				    | (u_int16_t)getub(buf, (off)+1)))
#define getlesl_be(buf, off)	(int32_t)((((u_int16_t)getleuw_be(buf, (off)) << 16) \
				    | getleuw_be(buf, (off)+2)))
#define getleul_be(buf, off)	(u_int32_t)((((u_int16_t)getleuw_be(buf, (off)) << 16) \
				    | getleuw_be(buf, (off)+2)))
#define getlesL_be(buf, off)	(int64_t)((((u_int64_t)getleul_be(buf, (off)) << 32) \
				    | getleul_be(buf, (off)+4)))
#define getleuL_be(buf, off)	(u_int64_t)((((u_int64_t)getleul_be(buf, (off)) << 32) \
				    | getleul_be(buf, (off)+4)))
#define getlesl24_be(buf,off)     (int32_t)(((u_int32_t)getub((buf), (off))<<24 \
				    | (u_int32_t)getub((buf), (off)+1)<<16 \
				    | (u_int32_t)getub((buf), (off)+2)<<8)>>8)

#define NAVCOM_CHANNELS	12

static u_int8_t checksum(unsigned char *buf, size_t len)
{
    size_t n;
    u_int8_t csum = (u_int8_t)0x00;
    for(n = 0; n < len; n++)
      csum ^= buf[n];
    return csum;
}

static bool navcom_send_cmd(struct gps_device_t *session, unsigned char *cmd, size_t len)
{
    gpsd_report(LOG_RAW, "Navcom: command dump: %s\n",
	gpsd_hexdump_wrapper(cmd, len, LOG_RAW));
    return (gpsd_write(session, cmd, len) == (ssize_t)len);
}

/* Data Request */
static void navcom_cmd_0x20(struct gps_device_t *session, u_int8_t block_id, u_int16_t rate)
{
    unsigned char msg[18];
    putbyte(msg, 0, 0x02);
    putbyte(msg, 1, 0x99);
    putbyte(msg, 2, 0x66);
    putbyte(msg, 3, 0x20);	/* Cmd ID */
    putleword(msg, 4, 0x000e);	/* Length */
    putbyte(msg, 6, 0x00);	/* Action */
    putbyte(msg, 7, 0x01);      /* Count of blocks */
    putbyte(msg, 8, block_id);	/* Data Block ID */
    putbyte(msg, 9, 0x02);	/* Logical Ports */
    putleword(msg, 10, rate);	/* Data rate */
    putbyte(msg, 12, 0x71);
    putbyte(msg, 13, 0x00);
    putleword(msg, 14, 0x0000);
    putbyte(msg, 16, checksum(msg+3, 13));
    putbyte(msg, 17, 0x03);
    (void)navcom_send_cmd(session, msg, 18);
    gpsd_report(LOG_PROG,
		"Navcom: sent command 0x20 (Data Request) "
		"- data block id = %02x at rate %02x\n",
		block_id, rate);
}

/*@ unused @*/
/* Changes the LED settings in the receiver */
static void UNUSED navcom_cmd_0x3f(struct gps_device_t *session)
{
    unsigned char msg[12];
    putbyte(msg, 0, 0x02);
    putbyte(msg, 1, 0x99);
    putbyte(msg, 2, 0x66);
    putbyte(msg, 3, 0x3f);	/* Cmd ID */
    putleword(msg, 4, 0x0008);
    putbyte(msg, 6, 0x01);	/* Action */
    putbyte(msg, 7, 0x00);	/* Reserved */
    putbyte(msg, 8, 0x02);	/* Link LED setting */
    putbyte(msg, 9, 0x0a);	/* Battery LED setting */
    putbyte(msg, 10, checksum(msg+3, 7));
    putbyte(msg, 11, 0x03);
    (void)navcom_send_cmd(session, msg, 12);
    gpsd_report(LOG_PROG,
		"Navcom: sent command 0x3f (LED Configuration Block)\n");
}

/* Test Support Block - Blinks the LEDs */
static void navcom_cmd_0x1c(struct gps_device_t *session, u_int8_t mode, u_int8_t length)
{
    unsigned char msg[12];
    putbyte(msg, 0, 0x02);
    putbyte(msg, 1, 0x99);
    putbyte(msg, 2, 0x66);
    putbyte(msg, 3, 0x1c);	/* Cmd ID */
    putleword(msg, 4, 0x0008);
    putbyte(msg, 6, 0x04);      /* Use ACK/NAK */
    putbyte(msg, 7, mode);	/* 0x01 or 0x02 */
    putbyte(msg, 8, length);    /* Only if mode == 0x01 */
    putbyte(msg, 9, 0x00);
    putbyte(msg, 10, checksum(msg+3, 7));
    putbyte(msg, 11, 0x03);
    (void)navcom_send_cmd(session, msg, 12);
    gpsd_report(LOG_PROG,
		"Navcom: sent command 0x1c (Test Support Block)\n");
    gpsd_report(LOG_IO,
		"Navcom: command 0x1c mode = %02x, length = %u\n",
		mode, length);
}

#ifdef ALLOW_RECONFIGURE
/* Serial Port Configuration */
static void navcom_cmd_0x11(struct gps_device_t *session, u_int8_t port_selection)
{
    /* NOTE - We only allow changing one port at a time,
       although the message supports doing both at once. */
    unsigned char msg[12];
    putbyte(msg, 0, 0x02);
    putbyte(msg, 1, 0x99);
    putbyte(msg, 2, 0x66);
    putbyte(msg, 3, 0x11);	/* Cmd ID */
    putleword(msg, 4, 0x0008);    /* Length */
    putbyte(msg, 6, 0x04);      /* Action - Use ACK/NAK) */
    putbyte(msg, 7, port_selection);
    putbyte(msg, 8, 0x00);      /* Reserved */
    putbyte(msg, 9, 0x00);      /* Reserved */
    putbyte(msg, 10, checksum(msg+3, 7));
    putbyte(msg, 11, 0x03);
    (void)navcom_send_cmd(session, msg, 12);
    gpsd_report(LOG_PROG,
		"Navcom: sent command 0x11 (Serial Port Configuration)\n");
    gpsd_report(LOG_IO,
		"Navcom: serial port selection: 0x%02x\n", port_selection);
}
#endif /* ALLOW_RECONFIGURE */

static void navcom_probe_subtype(struct gps_device_t *session, unsigned int seq)
{
    /* Request the following messages: */
    if (seq==0) {
	/*@ +charint @*/
	navcom_cmd_0x1c(session, 0x01, 5);      /* Blink LEDs on receiver */
	navcom_cmd_0x20(session, 0xae, 0x1770); /* Identification Block - send every 10 min*/
	navcom_cmd_0x20(session, 0xb1, 0x4000); /* PVT Block */
	navcom_cmd_0x20(session, 0xb5, 0x00c8); /* Pseudorange Noise Statistics - send every 20s */
	navcom_cmd_0x20(session, 0xb0, 0x4000); /* Raw Meas Data Block */
	navcom_cmd_0x20(session, 0x81, 0x0000); /* Packed Ephemeris Data - send once */
	navcom_cmd_0x20(session, 0x81, 0x4000); /* Packed Ephemeris Data */
	navcom_cmd_0x20(session, 0x86, 0x4000); /* Channel Status */
	navcom_cmd_0x20(session, 0x83, 0x4000); /* Ionosphere and UTC Data */
	navcom_cmd_0x20(session, 0xef, 0x0bb8); /* Clock Drift - send every 5 min */
	/*@ -charint @*/
    }
}

static void navcom_ping(struct gps_device_t *session)
{
/* NOTE - This allows us to know into which of the unit's various
	  serial ports we are connected.
	  Its value gets updated every time we receive a 0x06 (Ack)
	  message.  Note that if commands are being fed into the
	  unit from more than one port (which is entirely possible
	  although not necessarily a bright idea), there is a good
	  chance that we might misidentify our port */
    /*@ -type @*/
    session->driver.navcom.physical_port = 0xFF;

    navcom_cmd_0x1c(session, 0x02, 0);      /* Test Support Block */
    navcom_cmd_0x20(session, 0xae, 0x0000); /* Identification Block */
    navcom_cmd_0x20(session, 0x86, 0x000a); /* Channel Status */
    /*@ +type @*/
}

/* Ionosphere and UTC Data */
static gps_mask_t handle_0x83(struct gps_device_t *session)
{
    /* NOTE - At the present moment this is only being used
	      for determining the GPS-UTC time difference,
	      for which the iono data is not needed as far
	      as we are concerned.  However, I am still
	      reporting it (if debuglevel >= LOG_IO) as a
	      matter of interest */
/* 2^-30 */
#define SF_A0 (0.000000000931322574615478515625)
/* 2^-50 */
#define SF_A1 (0.000000000000000888178419700125)
/* 2^12 */
#define SF_TOT (4096)
/* 2^-30 */
#define SF_ALPHA0 (0.000000000931322574615478515625)
/* 2^-27 */
#define SF_ALPHA1 (0.000000007450580596923828125)
/* 2^-24 */
#define SF_ALPHA2 (0.000000059604644775390625)
/* 2^-24 */
#define SF_ALPHA3 (0.000000059604644775390625)
/* 2^11 */
#define SF_BETA0 (2048)
/* 2^14 */
#define SF_BETA1 (16384)
/* 2^16 */
#define SF_BETA2 (65536)
/* 2^16 */
#define SF_BETA3 (65536)
    unsigned char *buf = session->packet.outbuffer + 3;
    u_int16_t week = getleuw(buf, 3);
    u_int32_t tow = getleul(buf, 5);
    int8_t alpha0 = getsb(buf, 9);
    int8_t alpha1 = getsb(buf, 10);
    int8_t alpha2 = getsb(buf, 11);
    int8_t alpha3 = getsb(buf, 12);
    int8_t beta0 = getsb(buf, 13);
    int8_t beta1 = getsb(buf, 14);
    int8_t beta2 = getsb(buf, 15);
    int8_t beta3 = getsb(buf, 16);
    int32_t a1 = getlesl(buf, 17);
    int32_t a0 = getlesl(buf, 21);
    u_int8_t tot = getub(buf, 25);
    u_int8_t wnt = getub(buf, 26);
    int8_t dtls = getsb(buf, 27);
    u_int8_t wnlsf = getub(buf, 28);
    u_int8_t dn = getub(buf, 29);
    int8_t dtlsf = getsb(buf, 30);

    /*@ +charint +relaxtypes @*/
    /* Ref.: ICD-GPS-200C 20.3.3.5.2.4 */
    if ((week%256)*604800+tow/1000.0 < wnlsf*604800+dn*86400) {
	/* Effectivity time is in the future, use dtls */
	session->context->leap_seconds = (int)dtls;
    } else {
	/* Effectivity time is not in the future, use dtlsf */
	session->context->leap_seconds = (int)dtlsf;
    }
    /*@ -relaxtypes -charint @*/

    session->gpsdata.sentence_time = gpstime_to_unix((int)week, tow/1000.0)
	    - session->context->leap_seconds;

    gpsd_report(LOG_PROG,
		"Navcom: received packet type 0x83 (Ionosphere and UTC Data)\n");
    gpsd_report(LOG_IO,
		"Navcom: Scaled parameters follow:\n");
    gpsd_report(LOG_IO,
		"Navcom: GPS Week: %u, GPS Time of Week: %u (GPS Time: %f)\n",
		week, tow, week*604800+tow/1000.0);
    gpsd_report(LOG_IO,
		"Navcom: a0: %12.4E, a1: %12.4E, a2: %12.4E, a3: %12.4E, "
		"b0: %12.4E, b1: %12.4E, b2: %12.4E, b3: %12.4E\n",
		(double)alpha0*SF_ALPHA0, (double)alpha1*SF_ALPHA1,
		(double)alpha2*SF_ALPHA2, (double)alpha3*SF_ALPHA3,
		(double)beta0*SF_BETA0, (double)beta1*SF_BETA1,
		(double)beta2*SF_BETA2, (double)beta3*SF_BETA3);
    gpsd_report(LOG_IO,
		"Navcom: A0: %19.12E, A1: %19.12E\n", (double)a0*SF_A0, (double)a1*SF_A1);
    gpsd_report(LOG_IO,
		"Navcom: UTC Ref. Time: %lu, UTC Ref. Week: %u, dTls: %d\n",
		(unsigned long)tot*SF_TOT, wnt, dtls);
    gpsd_report(LOG_IO,
	       "Navcom: Week of leap seconds: %u, Day number of leap seconds: %u, dTlsf: %d\n",
	       wnlsf, dn, dtlsf);

    return 0; /* No flag for update of leap seconds (Not part of a fix) */

#undef SF_A0
#undef SF_A1
#undef SF_TOT
#undef SF_ALPHA0
#undef SF_ALPHA1
#undef SF_ALPHA2
#undef SF_ALPHA3
#undef SF_BETA0
#undef SF_BETA1
#undef SF_BETA2
#undef SF_BETA3
}

/* Acknowledgement (without error) */
static gps_mask_t handle_0x06(struct gps_device_t *session)
{
    unsigned char *buf = session->packet.outbuffer + 3;
    u_int8_t cmd_id = getub(buf, 3);
    u_int8_t port = getub(buf, 4);
    session->driver.navcom.physical_port = port; /* This tells us which serial port was used last */
    gpsd_report(LOG_PROG,
		"Navcom: received packet type 0x06 (Acknowledgement (without error))\n");
    /*@ -type @*/
    gpsd_report(LOG_IO,
		"Navcom: acknowledged command id 0x%02x on port %c\n",
		cmd_id, (port==0?'A':(port==1?'B':'?')));
    /*@ +type @*/
    return 0; /* Nothing updated */
}

/* Negative Acknowledge */
static gps_mask_t handle_0x15(struct gps_device_t *session)
{
    size_t n;
    unsigned char *buf = session->packet.outbuffer + 3;
    size_t msg_len = (size_t)getleuw(buf, 1);
    /*@ -type @*/
    u_int8_t port, cmd_id = getub(buf, 3);
    gpsd_report(LOG_PROG,
		"Navcom: received packet type 0x15 (Negative Acknowledge)\n");
    for (n=4; n<(msg_len-2); n+=2) {
	u_int8_t err_id = getub(buf, n);
	u_int8_t err_desc = getub(buf, n+1);
	gpsd_report(LOG_IO,
		    "Navcom: error id = 0x%02x, error description = 0x%02x\n",
		   err_id, err_desc);
    }
    port = getub(buf, n);
    gpsd_report(LOG_IO,
		"Navcom: negative acknowledge was for command id 0x%02x on port %c\n",
		cmd_id, (port==0?'A':(port==1?'B':'?')));
    /*@ -type @*/
    return 0; /* Nothing updated */
}

/* PVT Block */
static gps_mask_t handle_0xb1(struct gps_device_t *session)
{
    unsigned int n;
    unsigned char *buf = session->packet.outbuffer + 3;
    uint16_t week;
    uint32_t tow;
    uint32_t sats_used;
    int32_t lat, lon;
    /* Resolution of lat/lon values (2^-11) */
#define LL_RES (0.00048828125)
    uint8_t lat_fraction, lon_fraction;
    /* Resolution of lat/lon fractions (2^-15) */
#define LL_FRAC_RES (0.000030517578125)
    uint8_t nav_mode;
    int32_t ellips_height, altitude;
    /* Resolution of height and altitude values (2.0^-10) */
#define EL_RES (0.0009765625)
    double vel_north, vel_east, vel_up;
    /* Resolution of velocity values (2.0^-10) */
#define VEL_RES (0.0009765625)
    double track;
    uint8_t fom, gdop, pdop, hdop, vdop, tdop, tfom;
    /* This value means "undefined" */
#define DOP_UNDEFINED (255)

    int16_t ant_height_adj;
    int32_t set_delta_up;
    /* Resolution of delta north, east, and up,
       and ant. height adjustment values (1mm) */
#define D_RES (0.001)

#ifdef __UNUSED__
    /* Other values provided by the PVT block which we
       may want to provide in the future.  At the present
       moment, the gpsd protocol does not have a mechanism
       to make this available to the user */
    uint8_t dgps_conf;
    uint16_t max_dgps_age;
    uint8_t ext_nav_mode;
    int32_t set_delta_north, set_delta_east;
    uint8_t nav_failure_code;
#endif /* __UNUSED__ */

    /* Timestamp */
    week = (uint16_t)getleuw(buf, 3);
    tow = (uint32_t)getleul(buf, 5);
    session->gpsdata.fix.time = session->gpsdata.sentence_time = gpstime_to_unix((int)week, tow/1000.0) - session->context->leap_seconds;

    /* Satellites used */
    sats_used = (uint32_t)getleul(buf, 9);
    session->gpsdata.satellites_used = 0;
    for (n = 0; n < 31; n++) {
	if ((sats_used & (0x01 << n)) != 0)
	  session->gpsdata.used[session->gpsdata.satellites_used++] = (int)(n+1);
    }

    /* Get latitude, longitude */
    lat = getlesl(buf, 13);
    lon = getlesl(buf, 17);
    lat_fraction = (uint8_t)(getub(buf, 21) >> 4);
    lon_fraction = (uint8_t)(getub(buf, 21) & 0x0f);

    session->gpsdata.fix.latitude = (double)(lat * LL_RES + lat_fraction * LL_FRAC_RES ) / 3600;
    session->gpsdata.fix.longitude = (double)(lon * LL_RES + lon_fraction * LL_FRAC_RES ) / 3600;

    /* Nav mode */
    nav_mode = (uint8_t)getub(buf, 22);
    if (-nav_mode & 0x80) {
	session->gpsdata.status = STATUS_NO_FIX;
	session->gpsdata.fix.mode = MODE_NO_FIX;
    } else {
	session->gpsdata.fix.mode = (nav_mode & 0x40 ? MODE_3D : MODE_2D);
	session->gpsdata.status = (nav_mode & 0x03 ? STATUS_DGPS_FIX : STATUS_FIX);
    }

    /* Height Data */
    ellips_height = getlesl(buf, 23);
    altitude = getlesl(buf, 27);

    ant_height_adj = getlesw(buf, 51);
    set_delta_up = getlesl(buf, 79);

    session->gpsdata.fix.altitude = (double)(altitude * EL_RES)
	    + (ant_height_adj * D_RES) + (set_delta_up * D_RES);
    session->gpsdata.separation = (double)(ellips_height - altitude)*EL_RES
	    + (ant_height_adj * D_RES) + (set_delta_up * D_RES);

    /* Speed Data */
    vel_north = (double)getlesl24(buf, 31);
    vel_east = (double)getlesl24(buf, 34);
    /* vel_up = getlesl24(buf, 37); */
    vel_up = (double)getlesl24(buf, 37);

    track = atan2(vel_east, vel_north);
    if (track < 0)
	track += 2 * GPS_PI;
    session->gpsdata.fix.track = track * RAD_2_DEG;
    /*@ -evalorder @*/
    session->gpsdata.fix.speed = sqrt(pow(vel_east,2) + pow(vel_north,2)) * VEL_RES;
    /*@ +evalorder @*/
    session->gpsdata.fix.climb = vel_up * VEL_RES;

    /* Quality indicators */
    /*@ -type @*/
    fom  = getub(buf, 40);
    gdop = getub(buf, 41);
    pdop = getub(buf, 42);
    hdop = getub(buf, 43);
    vdop = getub(buf, 44);
    tdop = getub(buf, 45);
    tfom = getub(buf, 46);
    /*@ +type @*/

    /* splint apparently gets confused about C promotion rules. */
    /* "Assignment of arbitrary unsigned integral type to double" on these */
#ifndef S_SPLINT_S
    session->gpsdata.fix.eph = fom/100.0*1.96/*Two sigma*/;
    /* FIXME - Which units is tfom in (spec doesn't say) and
	       which units does gpsd require? (docs don't say) */
    session->gpsdata.fix.ept = tfom*1.96/*Two sigma*/;
    /* FIXME This cannot possibly be right */
    /* I cannot find where to get VRMS from in the Navcom output, though,
       and this value seems to agree with the output from other software */
    session->gpsdata.fix.epv = (double)fom/(double)hdop*(double)vdop/100.0*1.96/*Two sigma*/;

    if (gdop == DOP_UNDEFINED)
	session->gpsdata.gdop = NAN;
    else
	session->gpsdata.gdop = gdop/10.0;
    if (pdop == DOP_UNDEFINED)
	session->gpsdata.pdop = NAN;
    else
	session->gpsdata.pdop = pdop/10.0;
    if (hdop == DOP_UNDEFINED)
	session->gpsdata.hdop = NAN;
    else
	session->gpsdata.hdop = hdop/10.0;
    if (vdop == DOP_UNDEFINED)
	session->gpsdata.vdop = NAN;
    else
	session->gpsdata.vdop = vdop/10.0;
    if (tdop == DOP_UNDEFINED)
	session->gpsdata.tdop = NAN;
    else
	session->gpsdata.tdop = tdop/10.0;
#endif /* S_SPLINT_S */

    gpsd_report(LOG_PROG, "Navcom: received packet type 0xb1 (PVT Report)\n");
    gpsd_report(LOG_IO, "Navcom: navigation mode %s (0x%02x) - %s - %s\n",
		(-nav_mode&0x80?"invalid":"valid"), nav_mode,
		(nav_mode&0x40?"3D":"2D"), (nav_mode&0x03?"DGPS":"GPS"));
    gpsd_report(LOG_IO, "Navcom: latitude = %f, longitude = %f, altitude = %f, geoid = %f\n",
		session->gpsdata.fix.latitude, session->gpsdata.fix.longitude,
		session->gpsdata.fix.altitude, session->gpsdata.separation);
    gpsd_report(LOG_IO,
		"Navcom: velocities: north = %f, east = %f, up = %f (track = %f, speed = %f)\n",
		vel_north*VEL_RES, vel_east*VEL_RES, vel_up*VEL_RES,
		session->gpsdata.fix.track, session->gpsdata.fix.speed);
    gpsd_report(LOG_IO,
		"Navcom: hrms = %f, vrms = %f, gdop = %f, pdop = %f, "
		"hdop = %f, vdop = %f, tdop = %f\n",
		session->gpsdata.fix.eph, session->gpsdata.fix.epv,
		session->gpsdata.gdop, session->gpsdata.pdop,
		session->gpsdata.hdop, session->gpsdata.vdop,
		session->gpsdata.tdop);
#undef D_RES
#undef LL_RES
#undef LL_FRAC_RES
#undef EL_RES
#undef VEL_RES
#undef DOP_UNDEFINED

    return LATLON_SET | ALTITUDE_SET | CLIMB_SET | SPEED_SET | TRACK_SET
	| TIME_SET | STATUS_SET | MODE_SET | USED_SET | HERR_SET | VERR_SET
	| TIMERR_SET | DOP_SET | CYCLE_START_SET;
}

/* Packed Ephemeris Data */
static gps_mask_t handle_0x81(struct gps_device_t *session)
{
    /* Scale factors for everything */
    /* 2^-31 */
#define SF_TGD       (.000000000465661287307739257812)
    /* 2^4 */
#define SF_TOC     (16)
    /* 2^-55 */
#define SF_AF2       (.000000000000000027755575615628)
    /* 2^-43 */
#define SF_AF1       (.000000000000113686837721616029)
    /* 2^-31 */
#define SF_AF0       (.000000000465661287307739257812)
    /* 2^-5 */
#define SF_CRS       (.031250000000000000000000000000)
    /* 2^-43 */
#define SF_DELTA_N   (.000000000000113686837721616029)
    /* 2^-31 */
#define SF_M0	(.000000000465661287307739257812)
    /* 2^-29 */
#define SF_CUC       (.000000001862645149230957031250)
    /* 2^-33 */
#define SF_E	 (.000000000116415321826934814453)
    /* 2^-29 */
#define SF_CUS       (.000000001862645149230957031250)
    /* 2^-19 */
#define SF_SQRT_A    (.000001907348632812500000000000)
    /* 2^4 */
#define SF_TOE     (16)
    /* 2^-29 */
#define SF_CIC       (.000000001862645149230957031250)
    /* 2^-31 */
#define SF_OMEGA0    (.000000000465661287307739257812)
    /* 2^-29 */
#define SF_CIS       (.000000001862645149230957031250)
    /* 2^-31 */
#define SF_I0	(.000000000465661287307739257812)
    /* 2^-5 */
#define SF_CRC       (.031250000000000000000000000000)
    /* 2^-31 */
#define SF_OMEGA     (.000000000465661287307739257812)
    /* 2^-43 */
#define SF_OMEGADOT  (.000000000000113686837721616029)
    /* 2^-43 */
#define SF_IDOT      (.000000000000113686837721616029)

    unsigned char *buf = session->packet.outbuffer + 3;
    u_int8_t prn = getub(buf, 3);
    u_int16_t week = getleuw(buf, 4);
    u_int32_t tow = getleul(buf, 6);
    u_int16_t iodc = getleuw(buf, 10);
    /* And now the fun starts... everything that follows is
       raw GPS data minus parity */
    /* Subframe 1, words 3 to 10 minus parity */
    u_int16_t wn = (getleuw_be(buf, 12)&0xffc0)>>6;
    u_int8_t cl2 = (getub(buf, 13)&0x30)>>4;
    u_int8_t ura = getub(buf, 13)&0x0f;
    u_int8_t svh = (getub(buf, 14)&0xfc)>>2;
    /* We already have IODC from earlier in the message, so
       we do not decode again */
/*    u_int16_t iodc = (getub(buf, 14)&0x03)<<8;*/
    u_int8_t l2pd = (getub(buf, 15)&0x80)>>7;
    int8_t tgd = getsb(buf, 26);
/*    iodc |= getub(buf, 27);*/
    u_int16_t toc = getleuw_be(buf, 28);
    int8_t af2 = getsb(buf, 30);
    int16_t af1 = getlesw_be(buf, 31);
    /*@ -shiftimplementation @*/
    int32_t af0 = getlesl24_be(buf, 33)>>2;
    /*@ +shiftimplementation @*/
    /* Subframe 2, words 3 to 10 minus parity */
    u_int8_t iode = getub(buf, 36);
    int16_t crs = getlesw_be(buf, 37);
    int16_t delta_n = getlesw_be(buf, 39);
    int32_t m0 = getlesl_be(buf, 41);
    int16_t cuc = getlesw_be(buf, 45);
    u_int32_t e = getleul_be(buf, 47);
    int16_t cus = getlesw_be(buf, 51);
    u_int32_t sqrt_a = getleul_be(buf, 53);
    u_int16_t toe = getleuw_be(buf, 57);
    /* NOTE - Fit interval & AODO not collected */
    /* Subframe 3, words 3 to 10 minus parity */
    int16_t cic = getlesw_be(buf, 60);
    int32_t Omega0 = getlesl_be(buf, 62);
    int16_t cis = getlesw_be(buf, 66);
    int32_t i0 = getlesl_be(buf, 68);
    int16_t crc = getlesw_be(buf, 72);
    int32_t omega = getlesl_be(buf, 74);
    int32_t Omegadot = getlesl24_be(buf, 78);
    /*@ -predboolothers @*/
    /* Question: What is the proper way of shifting a signed int 2 bits to
     * the right, preserving sign? Answer: integer division by 4. */
    int16_t idot = (int16_t)(((getlesw_be(buf, 82)&0xfffc)/4)|(getub(buf, 82)&80?0xc000:0x0000));
    /*@ +predboolothers @*/
    char time_str[24];
    (void)unix_to_iso8601(gpstime_to_unix((int)wn, (double)(toc*SF_TOC)), time_str, sizeof(time_str));

    gpsd_report(LOG_PROG,
		"Navcom: received packet type 0x81 (Packed Ephemeris Data)\n");
    gpsd_report(LOG_IO,
		"Navcom: PRN: %u, Epoch: %u (%s), SV clock bias/drift/drift rate: %#19.12E/%#19.12E/%#19.12E\n",
		prn, toc*SF_TOC, time_str, ((double)af0)*SF_AF0, ((double)af1)*SF_AF1, ((double)af2)*SF_AF2);
    gpsd_report(LOG_IO,
		"Navcom: IODE (!AODE): %u Crs: %19.12e, Delta n: %19.12e, M0: %19.12e\n",
		iode, (double)crs*SF_CRS, (double)delta_n*SF_DELTA_N*GPS_PI, (double)m0*SF_M0*GPS_PI);
    gpsd_report(LOG_IO,
		"Navcom: Cuc: %19.12e, Eccentricity: %19.12e, Cus: %19.12e, A^1/2: %19.12e\n",
		(double)cuc*SF_CUC, (double)e*SF_E, (double)cus*SF_CUS, (double)sqrt_a*SF_SQRT_A);
    gpsd_report(LOG_IO,
		"Navcom: TOE: %u, Cic: %19.12e, Omega %19.12e, Cis: %19.12e\n",
		toe*SF_TOE, (double)cic*SF_CIC, (double)Omega0*SF_OMEGA0*GPS_PI,
		(double)cis*SF_CIS);
    gpsd_report(LOG_IO,
		"Navcom: i0: %19.12e, Crc: %19.12e, omega: %19.12e, Omega dot: %19.12e\n",
		(double)i0*SF_I0*GPS_PI, (double)crc*SF_CRC, (double)omega*SF_OMEGA*GPS_PI,
		(double)Omegadot*SF_OMEGADOT*GPS_PI);
    gpsd_report(LOG_IO,
		"Navcom: IDOT: %19.12e, Codes on L2: 0x%x, GPS Week: %u, L2 P data flag: %x\n",
		(double)idot*SF_IDOT*GPS_PI, cl2, week-(week%1024)+wn, l2pd);
    gpsd_report(LOG_IO,
		"Navcom: SV accuracy: 0x%x, SV health: 0x%x, TGD: %f, IODC (!AODC): %u\n",
		ura, svh, (double)tgd*SF_TGD, iodc);
    gpsd_report(LOG_IO,
		"Navcom: Transmission time: %u\n",
		tow);

#undef SF_TGD
#undef SF_TOC
#undef SF_AF2
#undef SF_AF1
#undef SF_AF0
#undef SF_CRS
#undef SF_DELTA_N
#undef SF_M0
#undef SF_CUC
#undef SF_E
#undef SF_CUS
#undef SF_SQRT_A
#undef SF_TOE
#undef SF_CIC
#undef SF_OMEGA0
#undef SF_CIS
#undef SF_I0
#undef SF_CRC
#undef SF_OMEGA
#undef SF_OMEGADOT
#undef SF_IDOT

    return 0;
}

/* Channel Status */
static gps_mask_t handle_0x86(struct gps_device_t *session)
{
    size_t n, i;
    u_int8_t prn, tracking_status, ele, ca_snr, p2_snr, log_channel, hw_channel, s;
    u_int16_t azm, dgps_age;
    unsigned char *buf = session->packet.outbuffer + 3;
    size_t msg_len = (size_t)getleuw(buf, 1);
    u_int16_t week = getleuw(buf, 3);
    u_int32_t tow = getleul(buf, 5);
    u_int8_t eng_status = getub(buf, 9);
    u_int16_t sol_status = getleuw(buf, 10);
    u_int8_t sats_visible = getub(buf, 12);
    u_int8_t sats_tracked = getub(buf, 13);
    u_int8_t sats_used = getub(buf, 14);
    u_int8_t pdop = getub(buf, 15);

    /* Timestamp and PDOP */
    session->gpsdata.sentence_time = gpstime_to_unix((int)week, tow/1000.0)
	    - session->context->leap_seconds;
    session->gpsdata.pdop = (int)pdop / 10.0;

    /* Satellite count */
    session->gpsdata.satellites = (int)sats_visible;
    session->gpsdata.satellites_used = (int)sats_used;

    /* Fix mode */
    switch(sol_status & 0x05)
    {
    case 0x05:
	session->gpsdata.status = STATUS_DGPS_FIX;
	break;
    case 0x01:
	session->gpsdata.status = STATUS_FIX;
	break;
    default:
	session->gpsdata.status = STATUS_NO_FIX;
    }

    /*@ -predboolothers @*/
    gpsd_report(LOG_PROG,
	       "Navcom: received packet type 0x86 (Channel Status) "
	       "- satellites: visible = %u, tracked = %u, used = %u\n",
	       sats_visible, sats_tracked, sats_used);
    gpsd_report(LOG_IO,
	       "Navcom: engine status = 0x%x, almanac = %s, time = 0x%x, pos = 0x%x\n",
	       eng_status&0x07, (eng_status&0x08?"valid":"invalid"),
	       eng_status&0x30>>4, eng_status&0xc0>>6);
    /*@ +predboolothers @*/

    /* Satellite details */
    i = 0;
    for(n = 17; n < msg_len; n += 14) {
	if(i >= MAXCHANNELS) {
	    gpsd_report(LOG_ERROR,
			"Navcom: packet type 0x86: too many satellites!\n");
	    gpsd_zero_satellites(&session->gpsdata);
	    return ERROR_SET;
	}
	prn = getub(buf, n);
	tracking_status = getub(buf, n+1);
	log_channel = getub(buf, n+2);
	ele = getub(buf, n+5);
	azm =  getleuw(buf, n+6);
	ca_snr = getub(buf, n+8);
	p2_snr = getub(buf, n+10);
	dgps_age = getleuw(buf, n+11);
	hw_channel = getub(buf, n+13);
	s = (unsigned char)0;
	/*@ -predboolothers +charint @*/
	/* NOTE - In theory, I think one would check for hw channel number to
	   see if one is dealing with a GPS or other satellite, but the
	   channel numbers reported bear no resemblance to what the spec
	   says should be.  So I check for the fact that if all three
	   values below are zero, one is not interested on this satellite */
	if (!(ele == 0 && azm == 0 && dgps_age == 0)) {
	    session->gpsdata.PRN[i] = (int)prn;
	    session->gpsdata.elevation[i] = (int)ele;
	    session->gpsdata.azimuth[i] = (int)azm;
	    /*@i1@*/s = session->gpsdata.ss[i++] = (p2_snr ? p2_snr : ca_snr) / 4;
	}
	gpsd_report(LOG_IO,
		    "Navcom: prn = %3u, ele = %02u, azm = %03u, snr = %d (%s), "
		    "dgps age = %.1fs, log ch = %d, hw ch = 0x%02x\n",
		    prn, ele, azm, s, (p2_snr?"P2":"C/A"),
		    (double)dgps_age*0.1, log_channel&0x3f, hw_channel);
	gpsd_report(LOG_IO,
		    "Navcom:	    sol. valid = %c, clock = %s, pos. = %s, "
		    "height = %s, err. code = 0x%x\n",
		    (sol_status&0x01?'Y':'N'), (sol_status&0x02?"stable":"unstable"),
		    (sol_status&0x04?"dgps":"unaided"), (sol_status&0x08?"solved":"constrained"),
		    (sol_status&0x01?0x00:sol_status&0x0f00>>8));
	/*@ +predboolothers -charint @*/
    }

    return PDOP_SET | SATELLITE_SET | STATUS_SET;
}

/* Raw Meas. Data Block */
static gps_mask_t handle_0xb0(struct gps_device_t *session)
{
    /* L1 wavelength (299792458m/s / 1575420000Hz) */
#define LAMBDA_L1 (.190293672798364880476317426464)
    size_t n;
    unsigned char *buf = session->packet.outbuffer + 3;
    size_t msg_len = (size_t)getleuw(buf, 1);
    u_int16_t week = getleuw(buf, 3);
    u_int32_t tow = getleul(buf, 5);
    u_int8_t tm_slew_acc = getub(buf, 9);
    u_int8_t status = getub(buf, 10);

    char time_str[24];
    (void)unix_to_iso8601(gpstime_to_unix((int)week, (double)tow/1000.0), time_str, sizeof(time_str));

    gpsd_report(LOG_PROG,
		"Navcom: received packet type 0xb0 (Raw Meas. Data Block)\n");
    /*@ -predboolothers @*/
    gpsd_report(LOG_IO,
		"Navcom: Epoch = %s, time slew accumulator = %u (1/1023mS), status = 0x%02x "
		"(%sclock %s - %u blocks follow)\n",
		time_str,
		tm_slew_acc, status, (status&0x80?"channel time set - ":""),
		(status&0x40?"stable":"not stable"), status&0x0f);
    /*@ +predboolothers @*/
    for (n=11; n<msg_len-1; n+=16) {
	u_int8_t sv_status = getub(buf, n);
	u_int8_t ch_status = getub(buf, n+1);
	u_int32_t ca_pseudorange = getleul(buf, n+2);
	/* integer division by 16 is a sign-preserving right shift of 4 bits */
	int32_t l1_phase = getlesl24(buf, n+6) / 16;
	u_int8_t l1_slips = (u_int8_t)(getlesl24(buf, n+6) & 0x0f);
	int16_t p1_ca_pseudorange = getlesw(buf, n+9);
	int16_t p2_ca_pseudorange = getlesw(buf, n+11);
	int32_t l2_phase = getlesl24(buf, n+13) / 16;
	u_int8_t l2_slips = (u_int8_t)(getlesl24(buf, n+13) & 0x0f);
	/*@ -predboolothers +charint @*/
	double c1 = (sv_status&0x80? (double)ca_pseudorange/16.0*LAMBDA_L1 : NAN);
	double l1 = (sv_status&0x80? (double)ca_pseudorange/16.0 + (double)l1_phase/256.0 : NAN);
	double l2 = (sv_status&0x20? ((double)ca_pseudorange/16.0
		    + (double)p2_ca_pseudorange/16.0)*(120.0/154.0)
		    +(double)l2_phase/256.0 : NAN);
	double p1 = (sv_status&0x40? c1 + (double)p1_ca_pseudorange/16.0*LAMBDA_L1 : NAN);
	double p2 = (sv_status&0x20? c1 + (double)p2_ca_pseudorange/16.0*LAMBDA_L1 : NAN);
	gpsd_report(LOG_IO+1,
		    "Navcom: >> sv status = 0x%02x (PRN %u - C/A & L1 %s - P1 %s - P2 & L2 %s)\n",
		    sv_status, (sv_status&0x1f), (sv_status&0x80?"valid":"invalid"),
		    (sv_status&0x40?"valid":"invalid"), (sv_status&0x20?"valid":"invalid"));
	gpsd_report(LOG_IO+1,
		    "Navcom: >>> ch status = 0x%02x (Logical channel: %u - CA C/No: %u dBHz) "
		    "sL1: %u, sL2: %u\n",
		    ch_status, ch_status&0x0f, ((ch_status&0xf0)>>4)+35, l1_slips, l2_slips);
	gpsd_report(LOG_IO+1,
		    "Navcom: >>> C1: %14.3f, L1: %14.3f, L2: %14.3f, P1: %14.3f, P2: %14.3f\n",
		    c1, l1, l2, p1, p2);
	/*@ +predboolothers -charint @*/
    }
#undef LAMBDA_L1
    return 0; /* Raw measurements not yet implemented in gpsd */
}

/* Pseudorange Noise Statistics */
static gps_mask_t handle_0xb5(struct gps_device_t *session)
{
    if(sizeof(double) == 8) {
	union long_double l_d;
	unsigned char *buf = session->packet.outbuffer + 3;
	u_int16_t week = getleuw(buf, 3);
	u_int32_t tow = getleul(buf, 5);
	double rms = getled(buf, 9);
#ifdef __UNUSED__
	/* Reason why it's unused is these figures do not agree
	with those obtained from the PVT report (handle_0xb1).
	The figures from 0xb1 do agree with the values reported
	by Navcom's PC utility */
	double ellips_maj = getled(buf, 17);
	double ellips_min = getled(buf, 25);
	double ellips_azm = getled(buf, 33);
	double lat_sd = getled(buf, 41);
	double lon_sd = getled(buf, 49);
	double alt_sd = getled(buf, 57);
	double hrms = sqrt(pow(lat_sd, 2) + pow(lon_sd, 2));
#endif /*  __UNUSED__ */
	session->gpsdata.epe = rms*1.96;
#ifdef __UNUSED__
	session->gpsdata.fix.eph = hrms*1.96;
	session->gpsdata.fix.epv = alt_sd*1.96;
#endif /*  __UNUSED__ */
	session->gpsdata.sentence_time = gpstime_to_unix((int)week, tow/1000.0)
		- session->context->leap_seconds;
	gpsd_report(LOG_PROG,
		    "Navcom: received packet type 0xb5 (Pseudorange Noise Statistics)\n");
	gpsd_report(LOG_IO,
		    "Navcom: epe = %f\n", session->gpsdata.epe);
	return TIME_SET | PERR_SET;
    } else {
	/* Ignore this message block */
	if (!session->driver.navcom.warned) {
	    gpsd_report(LOG_WARN,
			"Navcom: received packet type 0xb5 (Pseudorange Noise Statistics) ignored "
				" - sizeof(double) == 64 bits required\n");
	    session->driver.navcom.warned = true;
	}
	return 0; /* Block ignored - wrong sizeof(double) */
    }
}

/* LBM DSP Status Block */
static gps_mask_t handle_0xd3(struct gps_device_t *session UNUSED)
{
    /* This block contains status information about the
       unit's L-band (Inmarsat) module.  There is nothing
       interesting in it for our purposes so we do not deal
       with it.  This callback is purely to a) stop
       "unrecognised packet" messages appearing in the log
       and b) explain what it is for the curious */
    return 0;  /* Nothing updated */
}

/* Identification Block */
static gps_mask_t handle_0xae(struct gps_device_t *session)
{
    char *engconfstr, *asicstr;
    unsigned char *buf = session->packet.outbuffer + 3;
    size_t    msg_len = (size_t)getleuw(buf, 1);
    u_int8_t  engconf = getub(buf, 3);
    u_int8_t  asic    = getub(buf, 4);
    u_int8_t swvermaj = getub(buf, 5);
    u_int8_t swvermin = getub(buf, 6);
    u_int16_t dcser   = getleuw(buf, 7);
    u_int8_t  dcclass = getub(buf, 9);
    u_int16_t rfcser  = getleuw(buf, 10);
    u_int8_t  rfcclass= getub(buf, 12);
    /*@ -stringliteralnoroomfinalnull -type @*/
    u_int8_t  softtm[17] = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
    u_int8_t  bootstr[17] = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
    u_int8_t  ioptm[17] = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
    /*@ +stringliteralnoroomfinalnull +type @*/
    u_int8_t  iopvermaj  = (u_int8_t)0x00;
    u_int8_t  iopvermin  = (u_int8_t)0x00;
    u_int8_t  picver = (u_int8_t)0x00;
    u_int8_t  slsbn = (u_int8_t)0x00;
    u_int8_t  iopsbn = (u_int8_t)0x00;
    memcpy(softtm, &buf[13], 16);
    memcpy(bootstr, &buf[29], 16);
    if (msg_len == 0x0037) { /* No IOP */
	slsbn = getub(buf, 53);
    } else { /* IOP Present */
	iopvermaj  = getub(buf, 53);
	iopvermin  = getub(buf, 54);
	memcpy(ioptm, &buf[55], 16);
	picver     = getub(buf, 71);
	slsbn      = getub(buf, 72);
	iopsbn     = getub(buf, 73);
    }

    switch(engconf)
    {
    case 0x00:
	engconfstr = "Unknown/Undefined";
	break;
    case 0x01:
	engconfstr = "NCT 2000 S";
	break;
    case 0x02:
	engconfstr = "NCT 2000 D";
	break;
    case 0x03:
	engconfstr = "Startfire Single";
	break;
    case 0x04:
	engconfstr = "Starfire Dual";
	break;
    case 0x05:
	engconfstr = "Pole Mount RTK (Internal Radio)";
	break;
    case 0x06:
	engconfstr = "Pole Mount GIS (LBM)";
	break;
    case 0x07:
	engconfstr = "Black Box RTK (Internal Radio)";
	break;
    case 0x08:
	engconfstr = "Black Box GIS (LBM)";
	break;
    case 0x80:
	engconfstr = "R100";
	break;
    case 0x81:
	engconfstr = "R200";
	break;
    case 0x82:
	engconfstr = "R210";
	break;
    case 0x83:
	engconfstr = "R300";
	break;
    case 0x84:
	engconfstr = "R310";
	break;
    default:
	engconfstr = "?";
    }

    switch(asic)
    {
    case 0x01:
	asicstr = "A-ASIC";
	break;
    case 0x02:
	asicstr = "B-ASIC";
	break;
    case 0x03:
	asicstr = "C-ASIC";
	break;
    case 0x04:
	asicstr = "M-ASIC";
	break;
    default:
	asicstr = "?";
    }

    gpsd_report(LOG_PROG, "Navcom: received packet type 0xae (Identification Block)\n");
    if(msg_len == 0x0037) {
	gpsd_report(LOG_INF, "Navcom: ID Data: "
		    "%s %s Ver. %u.%u.%u, DC S/N: %u.%u, RF S/N: %u.%u, "
		    "Build ID: %s, Boot software: %s\n",
		    engconfstr, asicstr, swvermaj, swvermin, slsbn, dcser, dcclass,
		    rfcser, rfcclass, softtm, bootstr);
    } else {
	gpsd_report(LOG_INF, "Navcom: ID Data: "
		    "%s %s Ver. %u.%u.%u, DC S/N: %u.%u, RF S/N: %u.%u, "
		    "Build ID: %s, Boot software: %s, "
		    "IOP Ver.: %u.%u.%u, PIC: %u, IOP Build ID: %s\n",
		    engconfstr, asicstr, swvermaj, swvermin, slsbn, dcser, dcclass,
		    rfcser, rfcclass, softtm, bootstr, iopvermaj, iopvermin, iopsbn,
		    picver, ioptm);
    }

    /*@ -formattype @*/
    (void)snprintf(session->subtype, sizeof(session->subtype),
	     "%s %s Ver. %u.%u.%u S/N %u.%u %u.%u",
	     engconfstr, asicstr, swvermaj, swvermin, slsbn, dcser, dcclass,
	     rfcser, rfcclass);
    /*@ +formattype @*/
    return DEVICEID_SET;
}

/* Clock Drift and Offset */
static gps_mask_t handle_0xef(struct gps_device_t *session)
{
    unsigned char *buf = session->packet.outbuffer + 3;
    u_int16_t week = getleuw(buf, 3);
    u_int32_t tow = getleul(buf, 5);
    int8_t osc_temp = getsb(buf, 9);
    u_int8_t nav_status = getub(buf, 10);
    union long_double l_d;
    double nav_clock_offset;
    union int_float i_f;
    float nav_clock_drift;
    float osc_filter_drift_est;
    int32_t time_slew = (int32_t)getlesl(buf, 27);
    if (sizeof(double) == 8) {
	nav_clock_offset = getled(buf, 11);
    } else {
	nav_clock_offset = NAN;
    }
    if (sizeof(float) == 4) {
	nav_clock_drift = getlef(buf, 19);
	osc_filter_drift_est = getlef(buf, 23);
    } else {
	nav_clock_drift = NAN;
	osc_filter_drift_est = NAN;
    }

    session->gpsdata.sentence_time = gpstime_to_unix((int)week, tow/1000.0)
	    - session->context->leap_seconds;

    gpsd_report(LOG_PROG,
		"Navcom: received packet type 0xef (Clock Drift and Offset)\n");
    gpsd_report(LOG_IO,
		"Navcom: oscillator temp. = %d, nav. status = 0x%02x, "
		"nav. clock offset = %f, nav. clock drift = %f, "
		"osc. filter drift est. = %f, acc.time slew value = %d\n",
		osc_temp, nav_status, nav_clock_offset, nav_clock_drift,
		osc_filter_drift_est, time_slew);
    return TIME_SET;
}


/*@ +charint @*/
gps_mask_t navcom_parse(struct gps_device_t *session, unsigned char *buf, size_t len)
{
    unsigned char cmd_id;
    unsigned char *payload;
    unsigned int  msg_len;

    if (len == 0)
	return 0;

    cmd_id = getub(buf, 3);
    payload = &buf[6];
    msg_len = getleuw(buf, 4);

    /*@ -usedef -compdef @*/
    gpsd_report(LOG_RAW, "Navcom: packet type 0x%02x, length %d: %s\n",
	cmd_id, msg_len, gpsd_hexdump_wrapper(buf, len, LOG_RAW));
    /*@ +usedef +compdef @*/

    (void)snprintf(session->gpsdata.tag, sizeof(session->gpsdata.tag),
		   "0x%02x",cmd_id);

    switch (cmd_id)
    {
    case 0x06:
	return handle_0x06(session);
    case 0x15:
	return handle_0x15(session);
    case 0x81:
	return handle_0x81(session);
    case 0x83:
	return handle_0x83(session);
    case 0x86:
	return handle_0x86(session);
    case 0xae:
	return handle_0xae(session);
    case 0xb0:
	return handle_0xb0(session);
    case 0xb1:
	return handle_0xb1(session);
    case 0xb5:
	return handle_0xb5(session);
    case 0xd3:
	return handle_0xd3(session);
    case 0xef:
	return handle_0xef(session);
    default:
	gpsd_report(LOG_PROG,
		    "Navcom: received packet type 0x%02x, length %d - unknown or unimplemented\n",
		    cmd_id, msg_len);
	return 0;
    }
}
/*@ -charint @*/

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

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

#ifdef ALLOW_CONTROLSEND
static ssize_t navcom_control_send(struct gps_device_t *session, 
				char *buf, size_t len)
{
    /*@ +ignoresigns -mayaliasunique @*/
    putbyte(session->msgbuf, 0, 0x02);
    putbyte(session->msgbuf, 1, 0x99);
    putbyte(session->msgbuf, 2, 0x66);
    putbyte(session->msgbuf, 3, buf[0]);	/* Cmd ID */
    putleword(session->msgbuf, 4, len+4);	/* Length */
    memcpy(session->msgbuf, buf+6, len-1);
    putbyte(session->msgbuf, 6 + len, checksum((unsigned char *)session->msgbuf+3, len+5));
    putbyte(session->msgbuf, 7 + len, 0x03);
    session->msgbuflen = len+9;
    /*@ -ignoresigns +mayaliasunique @*/
    gpsd_report(LOG_RAW, "Navcom: control dump: %s\n",
	gpsd_hexdump_wrapper(session->msgbuf, session->msgbuflen, LOG_RAW));
    return gpsd_write(session, session->msgbuf, session->msgbuflen);
}
#endif /* ALLOW_CONTROLSEND */

#ifdef ALLOW_RECONFIGURE
static bool navcom_speed(struct gps_device_t *session, 
			 unsigned int speed, char parity, int stopbits)
{
    /* parity and stopbit switching aren't implemented */
    if (parity!=(char)session->gpsdata.parity || stopbits!=(int)session->gpsdata.parity) {
	return false;
    } else {
	u_int8_t port_selection;
	u_int8_t baud;
	if (session->driver.navcom.physical_port == (unsigned char)0xFF) {
	    /* We still don't know which port we're connected to */
	    return false;
	}
	/*@ +charint @*/
	switch (speed) {
	    /* NOTE - The spec says that certain baud combinations
		      on ports A and B are not allowed, those are
		      1200/115200, 2400/57600, and 2400/115200.
		      To try and minimise the possibility of those
		      occurring, we do not allow baud rates below
		      4800.  We could also disallow 57600 and 115200
		      to totally prevent this, but I do not consider
		      that reasonable.  Finding which baud speed the
		      other port is set at would also be too much
		      trouble, so we do not do it. */
	    case   4800:
		baud = 0x04;
		break;
	    case   9600:
		baud = 0x06;
		break;
	    case  19200:
		baud = 0x08;
		break;
	    case  38400:
		baud = 0x0a;
		break;
	    case  57600:
		baud = 0x0c;
		break;
	    case 115200:
		baud = 0x0e;
		break;
	    default:
		/* Unsupported speed */
		return false;
	}
	/*@ -charint @*/

	/* Proceed to construct our message */
	port_selection = session->driver.navcom.physical_port | baud;

	/* Send it off */
	navcom_cmd_0x11(session, port_selection);

	/* And cheekily return true, even though we have
	   no way to know if the speed change succeeded
	   until and if we receive an ACK (message 0x06),
	   which will be at the new baud speed if the
	   command was successful.  Bottom line, the client
	   should requery gpsd to see if the new speed is
	   different than the old one */
	return true;
    }
}
#endif /* ALLOW_RECONFIGURE */

/* this is everything we export */
const struct gps_type_t navcom_binary =
{
    .type_name      = "Navcom binary",  	/* full name of type */
    .packet_type    = NAVCOM_PACKET,		/* lexer packet type */
    .trigger	    = "\x02\x99\x66",		/* packet leader */
    .channels       = NAVCOM_CHANNELS,		/* 12 L1 + 12 L2 + 2 Inmarsat L-Band */
    .probe_wakeup   = navcom_ping,		/* wakeup to be done before hunt */
    .probe_detect   = NULL,			/* no probe */
    .probe_subtype  = navcom_probe_subtype,	/* subtype probing */
    .get_packet     = generic_get,		/* use generic one */
    .parse_packet   = navcom_parse_input,	/* parse message packets */
    .rtcm_writer    = pass_rtcm,		/* send RTCM data straight */
#ifdef ALLOW_CONTROLSEND
    .control_send   = navcom_control_send,	/* how to send a control string */
#endif /* ALLOW_CONTROLSEND */
#ifdef ALLOW_RECONFIGURE
    .configurator   = NULL,			/* no reconfigure */
    .speed_switcher = navcom_speed,		/* we do change baud rates */
    .mode_switcher  = NULL,			/* there is not a mode switcher */
    .rate_switcher  = NULL,			/* no sample-rate switcher */
    .min_cycle      = 1,			/* ignore, no rate switch */
    .revert	    = NULL,			/* no reversion code */
#endif /* ALLOW_RECONFIGURE */
    .wrapup	    = NULL,			/* ignore, no wrapup */
};

#endif /* defined(NAVCOM_ENABLE) && defined(BINARY_ENABLE) */