driver_proto.c

来自「gpsd, a popular GPS daemon.」· C语言 代码 · 共 409 行

/* $Id: driver_proto.c 4661 2008-01-19 22:54:23Z garyemiller $
 *
 * A prototype driver.  Doesn't run, doesn't even compile.
 *
 * For new driver authors: replace "PROTO" and "proto" with the name of
 * your new driver. That will give you a skeleton with all the required
 * functions defined.
 *
 * Once that is done, you will likely have to define a large number of
 * flags and masks. From there, you will be able to start extracting
 * useful quantities. There are roughed-in decoders for the navigation
 * solution, satellite status and gps-utc offset. These are the 3 key
 * messages that gpsd needs. Some protocols transmit error estimates
 * separately from the navigation solution; if developing a driver for
 * such a protocol you will need to add a decoder function for that
 * message.
 *
 * For anyone hacking this driver skeleton: "PROTO" and "proto" are now
 * reserved tokens. We suggest that they only ever be used as prefixes,
 * but if they are used infix, they must be used in a way that allows a
 * driver author to find-and-replace to create a unique namespace for
 * driver functions.
 *
 * In vi, ":%s/PROTO/MYDRIVER/g" and ":%s/proto/mydriver/g" must produce
 * a source file that can compile, even if it does nothing useful.
 *
 */

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

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

#include "bits.h"

/*
 * These routines are specific to this driver
 */

static	gps_mask_t proto_parse_input(struct gps_device_t *);
static	gps_mask_t proto_dispatch(struct gps_device_t *, unsigned char *, size_t );
static	gps_mask_t proto_msg_navsol(struct gps_device_t *, unsigned char *, size_t );
static	gps_mask_t proto_msg_utctime(struct gps_device_t *, unsigned char *, size_t );
static	gps_mask_t proto_msg_svinfo(struct gps_device_t *, unsigned char *, size_t );

/*
 * These methods may be called elsewhere in gpsd
 */
	bool proto_write(int , unsigned char *, size_t );
	void proto_set_mode(struct gps_device_t *, speed_t ):
static	bool proto_probe_detect(struct gps_device_t *)
static	void proto_probe_wakeup(struct gps_device_t *)
static	void proto_probe_subtype(struct gps_device_t *, unsigned int )
static	void proto_configurator(struct gps_device_t *, unsigned int )
static	bool proto_set_speed(struct gps_device_t *, speed_t )
static	void proto_set_mode(struct gps_device_t *, int )
static	void proto_revert(struct gps_device_t *)
static	void proto_wrapup(struct gps_device_t *)

/*
 * Decode the navigation solution message
 */
static gps_mask_t
proto_msg_navsol(struct gps_device_t *session, unsigned char *buf, size_t data_len)
{
    gps_mask_t mask;
    int flags;
    double Px, Py, Pz, Vx, Vy, Vz;

    if (data_len != PROTO_NAVSOL_MSG_LEN)
	return 0;

    /* if this protocol has a way to test message validity, use it */
    flags = GET_FLAGS();
    if ((flags & PROTO_SOLUTION_VALID) == 0)
	return 0;

    mask = ONLINE_SET;

    /* extract ECEF navigation solution here */
    /* or extract the local tangential plane (ENU) solution */
    [Px, Py, Pz, Vx, Vy, Vz] = GET_ECEF_FIX();
    ecef_to_wgs84fix(&session->gpsdata, Px, Py, Pz, Vx, Vy, Vz);
    mask |= LATLON_SET | ALTITUDE_SET | SPEED_SET | TRACK_SET | CLIMB_SET  ;

    session->gpsdata.fix.eph = GET_POSITION_ERROR();
    session->gpsdata.fix.eps = GET_SPEED_ERROR();
    session->gpsdata.satellites_used = GET_SATELLITES_USED();
    session->gpsdata.hdop = GET_HDOP();
    session->gpsdata.vdop = GET_VDOP();
    /* other DOP if available */
    mask |= HDOP_SET | VDOP_SET | USED_SET;

    session->gpsdata.fix.mode = GET_FIX_MODE();
    session->gpsdata.status = GET_FIX_STATUS();

    /* CYCLE_START_SET if this message starts a reporting period */
    mask |= MODE_SET | STATUS_SET | CYCLE_START_SET ;

    return mask;
}

/**
 * GPS Leap Seconds
 */
static gps_mask_t
proto_msg_utctime(struct gps_device_t *session, unsigned char *buf, size_t data_len)
{
    if (data_len != UTCTIME_MSG_LEN)
	return 0;

    /* if this protocol has a way to test message validity, use it */
    flags = GET_FLAGS();
    if ((flags & PROTO_TIME_VALID) == 0)
	return 0;

    tow = GET_MS_TIMEOFWEEK();
    gps_week = GET_WEEKNUMBER();
    session->context->leap_seconds = GET_GPS_LEAPSECONDS()

    t = gpstime_to_unix(gps_week, tow/1000.0) - session->context->leap_seconds;
    session->gpsdata.sentence_time = session->gpsdata.fix.time = t;

    return TIME_SET | ONLINE_SET;
}

/**
 * GPS Satellite Info
 */
static gps_mask_t
proto_msg_nav_svinfo(struct gps_device_t *session, unsigned char *buf, size_t data_len)
{
    unsigned char i, st, nchan, nsv;
    unsigned int tow;

    if (data_len != SVINFO_MSG_LEN )
	return 0;

    /* if this protocol has a way to test message validity, use it */
    flags = GET_FLAGS();
    if ((flags & PROTO_SVINFO_VALID) == 0)
	return 0;

    /*
     * some protocols have a variable length message listing only visible
     * satellites, even if there are less than the number of channels. others
     * have a fixed length message and send empty records for idle channels
     * that are not tracking or searching. whatever the case, nchan should
     * be set to the number of satellites which might be visible.
     */
    nchan = GET_NUMBER_OF_CHANNELS();
    gpsd_zero_satellites(&session->gpsdata);
    nsv = 0; /* number of actually used satellites */
    for (i = st = 0; i < nchan; i++) {
	/* get info for one channel/satellite */
	int off = GET_CHANNEL_STATUS(i);

	session->gpsdata.PRN[i]		= PRN_THIS_CHANNEL_IS_TRACKING(i);
	session->gpsdata.ss[i]		= SIGNAL_STRENGTH_FOR_CHANNEL(i);
	session->gpsdata.elevation[i]	= SV_ELEVATION_FOR_CHANNEL(i);
	session->gpsdata.azimuth[i]	= SV_AZIMUTH_FOR_CHANNEL(i);

	if (CHANNEL_USED_IN_SOLUTION(i))
	    session->gpsdata.used[nsv++] = session->gpsdata.PRN[i];

	if(session->gpsdata.PRN[i])
		st++;
    }
    session->gpsdata.satellites_used = nsv;
    session->gpsdata.satellites = st;
    return SATELLITE_SET | USED_SET;
}

/**
 * Write data to the device, doing any required padding or checksumming
 */
/*@ +charint -usedef -compdef @*/
static bool proto_write(int fd, unsigned char *msg, size_t msglen) 
{
   bool ok;

   /* CONSTRUCT THE MESSAGE */

   /* we may need to dump the message */
   gpsd_report(LOG_IO, "writing proto control type %02x:%s\n", 
	       msg[0], gpsd_hexdump(msg, msglen));
   ok = (write(fd, msg, msglen) == (ssize_t)msglen);
   (void)tcdrain(fd);
   return(ok);
}
/*@ -charint +usedef +compdef @*/

/**
 * Parse the data from the device
 */
/*@ +charint @*/
gps_mask_t proto_dispatch(struct gps_device_t *session, unsigned char *buf, size_t len)
{
    size_t i;
    int type, used, visible;
    double version;

    if (len == 0)
	return 0;

    type = GET_MESSAGE_TYPE();

    /* we may need to dump the raw packet */
    gpsd_report(LOG_RAW, "raw proto packet type 0x%02x length %d: %s\n",
	buf[0], len, buf2);

   /*
    * XXX The tag field is only 8 bytes; be careful you do not overflow.
    * XXX Using an abbreviation (eg. "italk" -> "itk") may be useful.
    */ 
    (void)snprintf(session->gpsdata.tag, sizeof(session->gpsdata.tag),
	"PROTO%02x", type);

    switch (type)
    {
	/* Deliver message to specific decoder based on message type */

    default:
	/* XXX This gets noisy in a hurry. Change once your driver works */
	gpsd_report(LOG_WARN, "unknown packet id %d length %d: %s\n",
	    type, len, gpsd_hexdump(buf, len));
	return 0;
    }
}
/*@ -charint @*/

/*
 * Switch between NMEA and binary mode, if supported
 */
static void proto_set_mode(struct gps_device_t *session, speed_t speed)
{
    /*
     * Insert your actual mode switching code here.
     */
}

/**********************************************************
 *
 * Externally called routines below here
 *
 **********************************************************/

static bool proto_probe_detect(struct gps_device_t *session)
{
   /*
    * This method is used to elicit a positively identifying
    * response from a candidate device. Some drivers may use
    * this to test for the presence of a certain kernel module.
    */
   int test, satisfied;

   /* Your testing code here */
   test=satisfied=0;
   if (test==satisfied)
      return true;
   return false;
}

static void proto_probe_wakeup(struct gps_device_t *session)
{
   /*
    * Code to make the device ready to communicate. This is
    * run every time we are about to try a different baud
    * rate in the autobaud sequence. Only needed if the
    * device is in some kind of sleeping state. If a wakeup
    * is not needed this method can be elided and the probe_wakeup
    * member of the gps_type_t structure can be set to NULL.
    */
}

static void proto_probe_subtype(struct gps_device_t *session, unsigned int seq)
{
    /*
     * Probe for subtypes here. If possible, get the software version and
     * store it in session->subtype.  The seq values don't actually mean 
     * anything, but conditionalizing probes on them gives the device 
     * time to respond to each one.
     */
}

static void proto_configurator(struct gps_device_t *session, unsigned int seq)
{
    /* Change sentence mix and set reporting modes as needed */
}

/*
 * This is the entry point to the driver. When the packet sniffer recognizes
 * a packet for this driver, it calls this method which passes the packet to
 * the binary processor or the nmea processor, depending on the session type.
 */
static gps_mask_t proto_parse_input(struct gps_device_t *session)
{
    gps_mask_t st;

    if (session->packet_type == PROTO_PACKET){
	st = proto_dispatch(session, session->outbuffer, session->outbuflen);
	session->gpsdata.driver_mode = 1;
	return st;
#ifdef NMEA_ENABLE
    } else if (session->packet_type == NMEA_PACKET) {
	st = nmea_parse((char *)session->outbuffer, session);
	session->gpsdata.driver_mode = 0;
	return st;
#endif /* NMEA_ENABLE */
    } else
	return 0;
}

static bool proto_set_speed(struct gps_device_t *session, speed_t speed)
{
    /* set port operating mode, speed, bits etc. here */
}

static void proto_set_mode(struct gps_device_t *session, int mode)
{
    if (mode == 0) {
	set_mode(session, session->gpsdata.baudrate);
	session->gpsdata.driver_mode = 0;
	(void)gpsd_switch_driver(session, "Generic NMEA");
    }
}

static void proto_revert(struct gps_device_t *session)
{
   /*
    * Reverse what the .configurator method changed.
    */
}

static void proto_wrapup(struct gps_device_t *session)
{
   /*
    * Do release actions that are independent of whether the .configurator 
    * method ran or not.
    */
}

/* The methods in this code take parameters and have */
/* return values that conform to the requirements AT */
/* THE TIME THE CODE WAS WRITTEN.                    */
/*                                                   */
/* These values may well have changed by the time    */
/* you read this and methods could have been added   */
/* or deleted. Unused methods can be set to NULL.    */
/*                                                   */
/* The latest situation can be found by inspecting   */
/* the contents of struct gps_type_t in gpsd.h.      */
/*                                                   */
/* This always contains the correct definitions that */
/* any driver must use to compile.                   */

/* This is everything we export */
struct gps_type_t proto_binary = {
    /* Full name of type */
    .type_name        = "Prototype driver",
    /* Response string that identifies device (not active) */
    .trigger          = NULL,
    /* Number of satellite channels supported by the device */
    .channels         = 12,
    /* Startup-time device detector */
    .probe_detect     = proto_probe_detect,
    /* Wakeup to be done before each baud hunt */
    .probe_wakeup     = proto_probe_wakeup,
    /* Initialize the device and get subtype */
    .probe_subtype    = proto_probe_subtype,
#ifdef ALLOW_RECONFIGURE
    /* Enable what reports we need */
    .configurator     = proto_configurator,
#endif /* ALLOW_RECONFIGURE */
    /* Packet getter (using default routine) */
    .get_packet       = generic_get,
    /* Parse message packets */
    .parse_packet     = proto_parse_input,
    /* RTCM handler (using default routine) */
    .rtcm_writer      = pass_rtcm,
    /* Speed (baudrate) switch */
    .speed_switcher   = proto_set_speed,
    /* Switch to NMEA mode */
    .mode_switcher    = proto_set_mode,
    /* Message delivery rate switcher (not active) */
    .rate_switcher    = NULL,
    /* Number of chars per report cycle (not active) */
    .cycle_chars      = -1,
#ifdef ALLOW_RECONFIGURE
    /* Undo the actions of .configurator */
    .revert           = proto_revert,
#endif /* ALLOW_RECONFIGURE */
    /* Puts device back to original settings */
    .wrapup           = proto_wrapup,
    /* Number of updates per second */
    .cycle            = 1
};
#endif /* defined(PROTO_ENABLE) && defined(BINARY_ENABLE) */