429 lines
11 KiB
C
429 lines
11 KiB
C
/*
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* refclock_arbiter - clock driver for Arbiter 1088A/B Satellite
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* Controlled Clock
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#if defined(REFCLOCK) && defined(CLOCK_ARBITER)
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#include "ntpd.h"
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#include "ntp_io.h"
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#include "ntp_refclock.h"
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#include "ntp_stdlib.h"
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#include <stdio.h>
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#include <ctype.h>
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/*
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* This driver supports the Arbiter 1088A/B Satellite Controlled Clock.
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* The claimed accuracy of this clock is 100 ns relative to the PPS
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* output when receiving four or more satellites.
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*
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* The receiver should be configured before starting the NTP daemon, in
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* order to establish reliable position and operating conditions. It
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* does not initiate surveying or hold mode. For use with NTP, the
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* daylight savings time feature should be disables (D0 command) and the
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* broadcast mode set to operate in UTC (BU command).
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*
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* The timecode format supported by this driver is selected by the poll
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* sequence "B5", which initiates a line in the following format to be
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* repeated once per second until turned off by the "B0" poll sequence.
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*
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* Format B5 (24 ASCII printing characters):
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*
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* <cr><lf>i yy ddd hh:mm:ss.000bbb
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*
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* on-time = <cr>
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* i = synchronization flag (' ' = locked, '?' = unlocked)
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* yy = year of century
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* ddd = day of year
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* hh:mm:ss = hours, minutes, seconds
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* .000 = fraction of second (not used)
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* bbb = tailing spaces for fill
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*
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* The alarm condition is indicated by a '?' at i, which indicates the
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* receiver is not synchronized. In normal operation, a line consisting
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* of the timecode followed by the time quality character (TQ) followed
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* by the receiver status string (SR) is written to the clockstats file.
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* The time quality character is encoded in IEEE P1344 standard:
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*
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* Format TQ (IEEE P1344 estimated worst-case time quality)
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*
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* 0 clock locked, maximum accuracy
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* F clock failure, time not reliable
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* 4 clock unlocked, accuracy < 1 us
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* 5 clock unlocked, accuracy < 10 us
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* 6 clock unlocked, accuracy < 100 us
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* 7 clock unlocked, accuracy < 1 ms
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* 8 clock unlocked, accuracy < 10 ms
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* 9 clock unlocked, accuracy < 100 ms
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* A clock unlocked, accuracy < 1 s
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* B clock unlocked, accuracy < 10 s
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*
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* The status string is encoded as follows:
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*
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* Format SR (25 ASCII printing characters)
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*
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* V=vv S=ss T=t P=pdop E=ee
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*
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* vv = satellites visible
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* ss = relative signal strength
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* t = satellites tracked
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* pdop = position dilution of precision (meters)
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* ee = hardware errors
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*
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* If flag4 is set, an additional line consisting of the receiver
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* latitude (LA), longitude (LO) and elevation (LH) (meters) is written
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* to this file. If channel B is enabled for deviation mode and connected
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* to a 1-PPS signal, the last two numbers on the line are the deviation
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* and standard deviation averaged over the last 15 seconds.
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*/
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/*
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* Interface definitions
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*/
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#define DEVICE "/dev/gps%d" /* device name and unit */
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#define SPEED232 B9600 /* uart speed (9600 baud) */
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#define PRECISION (-20) /* precision assumed (about 1 us) */
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#define REFID "GPS " /* reference ID */
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#define DESCRIPTION "Arbiter 1088A/B GPS Receiver" /* WRU */
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#define LENARB 24 /* format B5 timecode length */
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#define MAXSTA 30 /* max length of status string */
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#define MAXPOS 70 /* max length of position string */
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/*
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* ARB unit control structure
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*/
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struct arbunit {
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l_fp laststamp; /* last receive timestamp */
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int tcswitch; /* timecode switch/counter */
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char qualchar; /* IEEE P1344 quality (TQ command) */
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char status[MAXSTA]; /* receiver status (SR command) */
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char latlon[MAXPOS]; /* receiver position (lat/lon/alt) */
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};
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/*
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* Function prototypes
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*/
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static int arb_start P((int, struct peer *));
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static void arb_shutdown P((int, struct peer *));
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static void arb_receive P((struct recvbuf *));
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static void arb_poll P((int, struct peer *));
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/*
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* Transfer vector
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*/
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struct refclock refclock_arbiter = {
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arb_start, /* start up driver */
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arb_shutdown, /* shut down driver */
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arb_poll, /* transmit poll message */
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noentry, /* not used (old arb_control) */
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noentry, /* initialize driver (not used) */
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noentry, /* not used (old arb_buginfo) */
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NOFLAGS /* not used */
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};
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/*
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* arb_start - open the devices and initialize data for processing
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*/
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static int
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arb_start(
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int unit,
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struct peer *peer
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)
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{
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register struct arbunit *up;
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struct refclockproc *pp;
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int fd;
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char device[20];
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/*
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* Open serial port. Use CLK line discipline, if available.
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*/
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(void)sprintf(device, DEVICE, unit);
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if (!(fd = refclock_open(device, SPEED232, LDISC_CLK)))
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return (0);
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/*
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* Allocate and initialize unit structure
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*/
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if (!(up = (struct arbunit *)emalloc(sizeof(struct arbunit)))) {
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(void) close(fd);
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return (0);
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}
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memset((char *)up, 0, sizeof(struct arbunit));
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pp = peer->procptr;
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pp->io.clock_recv = arb_receive;
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pp->io.srcclock = (caddr_t)peer;
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pp->io.datalen = 0;
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pp->io.fd = fd;
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if (!io_addclock(&pp->io)) {
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(void) close(fd);
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free(up);
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return (0);
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}
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pp->unitptr = (caddr_t)up;
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/*
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* Initialize miscellaneous variables
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*/
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peer->precision = PRECISION;
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pp->clockdesc = DESCRIPTION;
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memcpy((char *)&pp->refid, REFID, 4);
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write(pp->io.fd, "B0", 2);
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return (1);
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}
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/*
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* arb_shutdown - shut down the clock
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*/
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static void
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arb_shutdown(
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int unit,
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struct peer *peer
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)
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{
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register struct arbunit *up;
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struct refclockproc *pp;
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pp = peer->procptr;
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up = (struct arbunit *)pp->unitptr;
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io_closeclock(&pp->io);
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free(up);
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}
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/*
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* arb_receive - receive data from the serial interface
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*/
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static void
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arb_receive(
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struct recvbuf *rbufp
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)
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{
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register struct arbunit *up;
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struct refclockproc *pp;
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struct peer *peer;
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l_fp trtmp;
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int temp;
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u_char syncchar; /* synchronization indicator */
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/*
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* Initialize pointers and read the timecode and timestamp
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*/
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peer = (struct peer *)rbufp->recv_srcclock;
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pp = peer->procptr;
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up = (struct arbunit *)pp->unitptr;
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temp = refclock_gtlin(rbufp, pp->a_lastcode, BMAX, &trtmp);
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/*
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* Note we get a buffer and timestamp for both a <cr> and <lf>,
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* but only the <cr> timestamp is retained. The program first
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* sends a TQ and expects the echo followed by the time quality
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* character. It then sends a B5 starting the timecode broadcast
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* and expects the echo followed some time later by the on-time
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* character <cr> and then the <lf> beginning the timecode
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* itself. Finally, at the <cr> beginning the next timecode at
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* the next second, the program sends a B0 shutting down the
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* timecode broadcast.
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*
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* If flag4 is set, the program snatches the latitude, longitude
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* and elevation and writes it to the clockstats file.
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*/
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if (temp == 0)
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return;
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pp->lastrec = up->laststamp;
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up->laststamp = trtmp;
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if (temp < 3)
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return;
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if (up->tcswitch == 0) {
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/*
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* Collect statistics. If nothing is recogized, just
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* ignore; sometimes the clock doesn't stop spewing
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* timecodes for awhile after the B0 commant.
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*/
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if (!strncmp(pp->a_lastcode, "TQ", 2)) {
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up->qualchar = pp->a_lastcode[2];
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write(pp->io.fd, "SR", 2);
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} else if (!strncmp(pp->a_lastcode, "SR", 2)) {
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strcpy(up->status, pp->a_lastcode + 2);
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if (pp->sloppyclockflag & CLK_FLAG4)
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write(pp->io.fd, "LA", 2);
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else {
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write(pp->io.fd, "B5", 2);
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up->tcswitch++;
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}
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} else if (!strncmp(pp->a_lastcode, "LA", 2)) {
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strcpy(up->latlon, pp->a_lastcode + 2);
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write(pp->io.fd, "LO", 2);
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} else if (!strncmp(pp->a_lastcode, "LO", 2)) {
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strcat(up->latlon, " ");
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strcat(up->latlon, pp->a_lastcode + 2);
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write(pp->io.fd, "LH", 2);
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} else if (!strncmp(pp->a_lastcode, "LH", 2)) {
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strcat(up->latlon, " ");
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strcat(up->latlon, pp->a_lastcode + 2);
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write(pp->io.fd, "DB", 2);
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} else if (!strncmp(pp->a_lastcode, "DB", 2)) {
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strcat(up->latlon, " ");
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strcat(up->latlon, pp->a_lastcode + 2);
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record_clock_stats(&peer->srcadr, up->latlon);
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write(pp->io.fd, "B5", 2);
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up->tcswitch++;
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}
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return;
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}
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pp->lencode = temp;
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/*
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* We get down to business, check the timecode format and decode
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* its contents. If the timecode has valid length, but not in
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* proper format, we declare bad format and exit. If the
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* timecode has invalid length, which sometimes occurs when the
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* B0 amputates the broadcast, we just quietly steal away. Note
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* that the time quality character and receiver status string is
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* tacked on the end for clockstats display.
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*/
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if (pp->lencode == LENARB) {
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/*
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* Timecode format B5: "i yy ddd hh:mm:ss.000 "
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*/
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pp->a_lastcode[LENARB - 2] = up->qualchar;
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strcat(pp->a_lastcode, up->status);
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syncchar = ' ';
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if (sscanf(pp->a_lastcode, "%c%2d %3d %2d:%2d:%2d",
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&syncchar, &pp->year, &pp->day, &pp->hour,
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&pp->minute, &pp->second) != 6) {
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refclock_report(peer, CEVNT_BADREPLY);
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write(pp->io.fd, "B0", 2);
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return;
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}
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} else {
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write(pp->io.fd, "B0", 2);
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return;
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}
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up->tcswitch++;
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/*
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* We decode the clock dispersion from the time quality
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* character.
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*/
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switch (up->qualchar) {
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case '0': /* locked, max accuracy */
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pp->disp = 1e-7;
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break;
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case '4': /* unlock accuracy < 1 us */
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pp->disp = 1e-6;
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break;
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case '5': /* unlock accuracy < 10 us */
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pp->disp = 1e-5;
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break;
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case '6': /* unlock accuracy < 100 us */
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pp->disp = 1e-4;
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break;
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case '7': /* unlock accuracy < 1 ms */
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pp->disp = .001;
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break;
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case '8': /* unlock accuracy < 10 ms */
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pp->disp = .01;
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break;
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case '9': /* unlock accuracy < 100 ms */
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pp->disp = .1;
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break;
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case 'A': /* unlock accuracy < 1 s */
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pp->disp = 1;
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break;
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case 'B': /* unlock accuracy < 10 s */
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pp->disp = 10;
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break;
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case 'F': /* clock failure */
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pp->disp = MAXDISPERSE;
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refclock_report(peer, CEVNT_FAULT);
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write(pp->io.fd, "B0", 2);
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return;
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default:
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pp->disp = MAXDISPERSE;
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refclock_report(peer, CEVNT_BADREPLY);
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write(pp->io.fd, "B0", 2);
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return;
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}
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if (syncchar != ' ')
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pp->leap = LEAP_NOTINSYNC;
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else
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pp->leap = LEAP_NOWARNING;
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#ifdef DEBUG
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if (debug)
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printf("arbiter: timecode %d %s\n", pp->lencode,
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pp->a_lastcode);
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#endif
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if (up->tcswitch >= NSTAGE)
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write(pp->io.fd, "B0", 2);
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/*
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* Process the new sample in the median filter and determine the
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* timecode timestamp.
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*/
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if (!refclock_process(pp))
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refclock_report(peer, CEVNT_BADTIME);
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}
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/*
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* arb_poll - called by the transmit procedure
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*/
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static void
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arb_poll(
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int unit,
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struct peer *peer
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)
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{
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register struct arbunit *up;
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struct refclockproc *pp;
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/*
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* Time to poll the clock. The Arbiter clock responds to a "B5"
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* by returning a timecode in the format specified above.
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* Transmission occurs once per second, unless turned off by a
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* "B0". Note there is no checking on state, since this may not
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* be the only customer reading the clock. Only one customer
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* need poll the clock; all others just listen in. If nothing is
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* heard from the clock for two polls, declare a timeout and
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* keep going.
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*/
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pp = peer->procptr;
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up = (struct arbunit *)pp->unitptr;
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up->tcswitch = 0;
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if (write(pp->io.fd, "TQ", 2) != 2) {
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refclock_report(peer, CEVNT_FAULT);
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} else
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pp->polls++;
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if (pp->coderecv == pp->codeproc) {
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refclock_report(peer, CEVNT_TIMEOUT);
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return;
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}
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record_clock_stats(&peer->srcadr, pp->a_lastcode);
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refclock_receive(peer);
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}
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#else
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int refclock_arbiter_bs;
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#endif /* REFCLOCK */
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