261 lines
8.1 KiB
C
261 lines
8.1 KiB
C
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/* $NetBSD: refclock_local.c,v 1.1.1.1 2000/03/29 12:38:53 simonb Exp $ */
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/* wjm 17-aug-1995: add a hook for special treatment of VMS_LOCALUNIT */
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/*
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* refclock_local - local pseudo-clock driver
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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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#ifdef REFCLOCK
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#include <stdio.h>
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#include <ctype.h>
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#include <sys/time.h>
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#include "ntpd.h"
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#include "ntp_refclock.h"
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#include "ntp_stdlib.h"
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#ifdef KERNEL_PLL
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#include "ntp_syscall.h"
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#endif
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/*
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* This is a hack to allow a machine to use its own system clock as a
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* reference clock, i.e., to free-run using no outside clock discipline
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* source. This is useful if you want to use NTP in an isolated
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* environment with no radio clock or NIST modem available. Pick a
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* machine that you figure has a good clock oscillator and configure it
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* with this driver. Set the clock using the best means available, like
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* eyeball-and-wristwatch. Then, point all the other machines at this
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* one or use broadcast (not multicast) mode to distribute time.
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*
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* Another application for this driver is if you want to use a
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* particular server's clock as the clock of last resort when all other
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* normal synchronization sources have gone away. This is especially
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* useful if that server has an ovenized oscillator. For this you would
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* configure this driver at a higher stratum (say 3 or 4) to prevent the
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* server's stratum from falling below that.
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*
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* A third application for this driver is when an external discipline
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* source is available, such as the NIST "lockclock" program, which
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* synchronizes the local clock via a telephone modem and the NIST
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* Automated Computer Time Service (ACTS), or the Digital Time
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* Synchronization Service (DTSS), which runs on DCE machines. In this
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* case the stratum should be set at zero, indicating a bona fide
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* stratum-1 source. Exercise some caution with this, since there is no
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* easy way to telegraph via NTP that something might be wrong in the
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* discipline source itself. In the case of DTSS, the local clock can
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* have a rather large jitter, depending on the interval between
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* corrections and the intrinsic frequency error of the clock
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* oscillator. In extreme cases, this can cause clients to exceed the
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* 128-ms slew window and drop off the NTP subnet.
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*
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* THis driver includes provisions to telegraph synchronization state
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* and related variables by means of kernel variables with specially
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* modified kernels. This is done using the ntp_adjtime() syscall.
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* In the cases where another protocol or device synchronizes the local
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* host, the data given to the kernel can be slurped up by this driver
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* and distributed to clients by ordinary NTP messaging.
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*
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* In the default mode the behavior of the clock selection algorithm is
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* modified when this driver is in use. The algorithm is designed so
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* that this driver will never be selected unless no other discipline
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* source is available. This can be overriden with the prefer keyword of
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* the server configuration command, in which case only this driver will
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* be selected for synchronization and all other discipline sources will
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* be ignored. This behavior is intended for use when an external
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* discipline source controls the system clock.
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*
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* Fudge Factors
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*
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* The stratum for this driver set at 3 by default, but it can be changed
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* by the fudge command and/or the ntpdc utility. The reference ID is
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* "LCL" by default, but can be changed using the same mechanism. *NEVER*
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* configure this driver to operate at a stratum which might possibly
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* disrupt a client with access to a bona fide primary server, unless the
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* local clock oscillator is reliably disciplined by another source.
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* *NEVER NEVER* configure a server which might devolve to an undisciplined
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* local clock to use multicast mode. Always remember that an improperly
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* configured local clock driver let loose in the Internet can cause
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* very serious disruption. This is why most of us who care about good
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* time use cryptographic authentication.
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*
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* This driver provides a mechanism to trim the local clock in both time
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* and frequency, as well as a way to manipulate the leap bits. The
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* fudge time1 parameter adjusts the time, in seconds, and the fudge
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* time2 parameter adjusts the frequency, in ppm. The fudge time1 parameter
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* is additive; that is, it adds an increment to the current time. The
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* fudge time2 parameter directly sets the frequency.
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*/
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/*
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* Local interface definitions
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*/
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#define PRECISION (-7) /* about 10 ms precision */
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#define REFID "LCL\0" /* reference ID */
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#define DESCRIPTION "Undisciplined local clock" /* WRU */
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#define STRATUM 3 /* default stratum */
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#define DISPERSION .01 /* default dispersion (10 ms) */
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/*
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* Imported from the timer module
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*/
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extern u_long current_time;
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/*
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* Imported from ntp_proto
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*/
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extern s_char sys_precision;
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#ifdef KERNEL_PLL
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/*
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* Imported from ntp_loopfilter
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*/
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extern int pll_control; /* kernel pll control */
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extern int kern_enable; /* kernel pll enabled */
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extern int ext_enable; /* external clock enable */
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#endif /* KERNEL_PLL */
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/*
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* Function prototypes
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*/
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static int local_start P((int, struct peer *));
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static void local_poll P((int, struct peer *));
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/*
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* Local variables
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*/
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static u_long poll_time; /* last time polled */
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/*
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* Transfer vector
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*/
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struct refclock refclock_local = {
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local_start, /* start up driver */
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noentry, /* shut down driver (not used) */
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local_poll, /* transmit poll message */
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noentry, /* not used (old lcl_control) */
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noentry, /* initialize driver (not used) */
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noentry, /* not used (old lcl_buginfo) */
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NOFLAGS /* not used */
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};
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/*
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* local_start - start up the clock
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*/
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static int
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local_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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struct refclockproc *pp;
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pp = peer->procptr;
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/*
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* Initialize miscellaneous variables
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*/
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peer->precision = sys_precision;
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peer->stratum = STRATUM;
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pp->clockdesc = DESCRIPTION;
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memcpy((char *)&pp->refid, REFID, 4);
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#if defined(VMS) && defined(VMS_LOCALUNIT)
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/* provide a non-standard REFID */
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if(unit == VMS_LOCALUNIT)
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memcpy((char *)&pp->refid,"LCLv",4);
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#endif /* VMS && VMS_LOCALUNIT */
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poll_time = current_time;
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return (1);
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}
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/*
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* local_poll - called by the transmit procedure
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*/
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static void
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local_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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struct refclockproc *pp;
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#if defined(KERNEL_PLL) && defined(STA_CLK)
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struct timex ntv;
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int retval;
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#endif /* KERNEL_PLL STA_CLK */
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#if defined(VMS) && defined(VMS_LOCALUNIT)
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if(unit == VMS_LOCALUNIT) {
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extern void vms_local_poll(struct peer *);
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vms_local_poll(peer);
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return;
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}
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#endif /* VMS && VMS_LOCALUNIT */
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pp = peer->procptr;
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pp->polls++;
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/*
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* Ramble through the usual filtering and grooming code, which
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* is essentially a no-op and included mostly for pretty
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* billboards. We allow a one-time time adjustment using fudge
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* time1 (s) and a continuous frequency adjustment using fudge
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* time 2 (ppm).
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*/
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get_systime(&pp->lastrec);
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pp->fudgetime1 += pp->fudgetime2 * 1e-6 * (current_time -
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poll_time);
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poll_time = current_time;
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refclock_process_offset(pp, pp->lastrec, pp->lastrec, pp->fudgetime1);
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pp->leap = LEAP_NOWARNING;
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pp->disp = DISPERSION;
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pp->variance = 0;
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#if defined(KERNEL_PLL) && defined(STA_CLK)
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/*
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* If the kernel pll code is up and running, somebody else
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* may come diddle the clock. If so, they better use ntp_adjtime(),
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* and set the STA_CLK bit in the status word. In this case, the
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* performance information is read from the kernel and becomes the
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* variables presented to the clock mitigation process.
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*/
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if (pll_control && kern_enable && (peer->flags & FLAG_PREFER)) {
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memset((char *)&ntv, 0, sizeof ntv);
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retval = ntp_adjtime(&ntv);
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if (ntv.status & STA_CLK) {
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ext_enable = 1;
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switch(retval) {
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case TIME_OK:
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pp->leap = LEAP_NOWARNING;
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break;
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case TIME_INS:
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pp->leap = LEAP_ADDSECOND;
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break;
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case TIME_DEL:
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pp->leap = LEAP_DELSECOND;
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break;
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case TIME_ERROR:
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pp->leap = LEAP_NOTINSYNC;
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}
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pp->disp = ntv.maxerror / 1e6;
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pp->variance = SQUARE(ntv.esterror / 1e6);
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}
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} else {
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ext_enable = 0;
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}
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#endif /* KERNEL_PLL STA_CLK */
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refclock_receive(peer);
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pp->fudgetime1 = 0;
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}
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#endif /* REFCLOCK */
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