/*
* refclock_transmit - simulate the transmit procedure
*
* This routine implements the NTP transmit procedure for a reference
* clock. This provides a mechanism to call the driver at the NTP poll
* interval, as well as provides a reachability mechanism to detect a
* broken radio or other madness.
*/
void
refclock_transmit(
struct peer *peer /* peer structure pointer */
)
{
u_char clktype;
int unit;
clktype = peer->refclktype;
unit = peer->refclkunit;
peer->sent++;
get_systime(&peer->xmt);
/*
* This is a ripoff of the peer transmit routine, but
* specialized for reference clocks. We do a little less
* protocol here and call the driver-specific transmit routine.
*/
if (peer->burst == 0) {
u_char oreach;
#ifdef DEBUG
if (debug)
printf("refclock_transmit: at %ld %s\n",
current_time, stoa(&(peer->srcadr)));
#endif
/*
* Update reachability and poll variables like the
* network code.
*/
oreach = peer->reach;
peer->reach <<= 1;
peer->outdate = current_time;
if (!peer->reach) {
if (oreach) {
report_event(EVNT_UNREACH, peer);
peer->timereachable = current_time;
}
} else {
if (!(oreach & 0x07)) {
clock_filter(peer, 0., 0., MAXDISPERSE);
clock_select();
}
if (peer->flags & FLAG_BURST)
peer->burst = NSTAGE;
}
} else {
peer->burst--;
}
if (refclock_conf[clktype]->clock_poll != noentry)
(refclock_conf[clktype]->clock_poll)(unit, peer);
poll_update(peer, peer->hpoll);
}
/*
* local_clock - the NTP logical clock loop filter.
*
* Return codes:
* -1 update ignored: exceeds panic threshold
* 0 update ignored: popcorn or exceeds step threshold
* 1 clock was slewed
* 2 clock was stepped
*
* LOCKCLOCK: The only thing this routine does is set the
* sys_rootdisp variable equal to the peer dispersion.
*/
int
local_clock(
struct peer *peer, /* synch source peer structure */
double fp_offset /* clock offset (s) */
)
{
int rval; /* return code */
int osys_poll; /* old system poll */
int ntp_adj_ret; /* returned by ntp_adjtime */
double mu; /* interval since last update */
double clock_frequency; /* clock frequency */
double dtemp, etemp; /* double temps */
char tbuf[80]; /* report buffer */
/*
* If the loop is opened or the NIST LOCKCLOCK is in use,
* monitor and record the offsets anyway in order to determine
* the open-loop response and then go home.
*/
#ifdef LOCKCLOCK
{
#else
if (!ntp_enable) {
#endif /* LOCKCLOCK */
record_loop_stats(fp_offset, drift_comp, clock_jitter,
clock_stability, sys_poll);
return (0);
}
#ifndef LOCKCLOCK
/*
* If the clock is way off, panic is declared. The clock_panic
* defaults to 1000 s; if set to zero, the panic will never
* occur. The allow_panic defaults to FALSE, so the first panic
* will exit. It can be set TRUE by a command line option, in
* which case the clock will be set anyway and time marches on.
* But, allow_panic will be set FALSE when the update is less
* than the step threshold; so, subsequent panics will exit.
*/
if (fabs(fp_offset) > clock_panic && clock_panic > 0 &&
!allow_panic) {
snprintf(tbuf, sizeof(tbuf),
"%+.0f s; set clock manually within %.0f s.",
fp_offset, clock_panic);
report_event(EVNT_SYSFAULT, NULL, tbuf);
return (-1);
}
/*
* This section simulates ntpdate. If the offset exceeds the
* step threshold (128 ms), step the clock to that time and
* exit. Otherwise, slew the clock to that time and exit. Note
* that the slew will persist and eventually complete beyond the
* life of this program. Note that while ntpdate is active, the
* terminal does not detach, so the termination message prints
* directly to the terminal.
*/
if (mode_ntpdate) {
if ( ( fp_offset > clock_max_fwd && clock_max_fwd > 0)
|| (-fp_offset > clock_max_back && clock_max_back > 0)) {
step_systime(fp_offset);
msyslog(LOG_NOTICE, "ntpd: time set %+.6f s",
fp_offset);
printf("ntpd: time set %+.6fs\n", fp_offset);
} else {
adj_systime(fp_offset);
msyslog(LOG_NOTICE, "ntpd: time slew %+.6f s",
fp_offset);
printf("ntpd: time slew %+.6fs\n", fp_offset);
}
record_loop_stats(fp_offset, drift_comp, clock_jitter,
clock_stability, sys_poll);
exit (0);
}
/*
* The huff-n'-puff filter finds the lowest delay in the recent
* interval. This is used to correct the offset by one-half the
* difference between the sample delay and minimum delay. This
* is most effective if the delays are highly assymetric and
* clockhopping is avoided and the clock frequency wander is
* relatively small.
*/
if (sys_huffpuff != NULL) {
if (peer->delay < sys_huffpuff[sys_huffptr])
sys_huffpuff[sys_huffptr] = peer->delay;
if (peer->delay < sys_mindly)
sys_mindly = peer->delay;
if (fp_offset > 0)
dtemp = -(peer->delay - sys_mindly) / 2;
else
dtemp = (peer->delay - sys_mindly) / 2;
fp_offset += dtemp;
#ifdef DEBUG
if (debug)
printf(
"local_clock: size %d mindly %.6f huffpuff %.6f\n",
sys_hufflen, sys_mindly, dtemp);
#endif
}
/*
* Clock state machine transition function which defines how the
* system reacts to large phase and frequency excursion. There
* are two main regimes: when the offset exceeds the step
* threshold (128 ms) and when it does not. Under certain
* conditions updates are suspended until the stepout theshold
* (900 s) is exceeded. See the documentation on how these
* thresholds interact with commands and command line options.
*
* Note the kernel is disabled if step is disabled or greater
* than 0.5 s or in ntpdate mode.
*/
osys_poll = sys_poll;
if (sys_poll < peer->minpoll)
sys_poll = peer->minpoll;
if (sys_poll > peer->maxpoll)
sys_poll = peer->maxpoll;
mu = current_time - clock_epoch;
clock_frequency = drift_comp;
rval = 1;
if ( ( fp_offset > clock_max_fwd && clock_max_fwd > 0)
|| (-fp_offset > clock_max_back && clock_max_back > 0)
|| force_step_once ) {
if (force_step_once) {
force_step_once = FALSE; /* we want this only once after startup */
msyslog(LOG_NOTICE, "Doing intital time step" );
}
switch (state) {
/*
* In SYNC state we ignore the first outlyer and switch
* to SPIK state.
*/
case EVNT_SYNC:
snprintf(tbuf, sizeof(tbuf), "%+.6f s",
fp_offset);
report_event(EVNT_SPIK, NULL, tbuf);
state = EVNT_SPIK;
return (0);
/*
* In FREQ state we ignore outlyers and inlyers. At the
* first outlyer after the stepout threshold, compute
* the apparent frequency correction and step the phase.
*/
case EVNT_FREQ:
if (mu < clock_minstep)
return (0);
clock_frequency = direct_freq(fp_offset);
/* fall through to EVNT_SPIK */
/*
* In SPIK state we ignore succeeding outlyers until
* either an inlyer is found or the stepout threshold is
* exceeded.
*/
case EVNT_SPIK:
if (mu < clock_minstep)
return (0);
/* fall through to default */
/*
* We get here by default in NSET and FSET states and
* from above in FREQ or SPIK states.
*
* In NSET state an initial frequency correction is not
* available, usually because the frequency file has not
* yet been written. Since the time is outside the step
* threshold, the clock is stepped. The frequency will
* be set directly following the stepout interval.
*
* In FSET state the initial frequency has been set from
* the frequency file. Since the time is outside the
* step threshold, the clock is stepped immediately,
* rather than after the stepout interval. Guys get
* nervous if it takes 15 minutes to set the clock for
* the first time.
*
* In FREQ and SPIK states the stepout threshold has
* expired and the phase is still above the step
* threshold. Note that a single spike greater than the
* step threshold is always suppressed, even with a
* long time constant.
*/
default:
snprintf(tbuf, sizeof(tbuf), "%+.6f s",
fp_offset);
report_event(EVNT_CLOCKRESET, NULL, tbuf);
step_systime(fp_offset);
reinit_timer();
tc_counter = 0;
clock_jitter = LOGTOD(sys_precision);
rval = 2;
if (state == EVNT_NSET) {
rstclock(EVNT_FREQ, 0);
return (rval);
}
break;
}
rstclock(EVNT_SYNC, 0);
} else {
/*
* The offset is less than the step threshold. Calculate
* the jitter as the exponentially weighted offset
* differences.
*/
etemp = SQUARE(clock_jitter);
dtemp = SQUARE(max(fabs(fp_offset - last_offset),
LOGTOD(sys_precision)));
clock_jitter = SQRT(etemp + (dtemp - etemp) /
CLOCK_AVG);
switch (state) {
/*
* In NSET state this is the first update received and
* the frequency has not been initialized. Adjust the
* phase, but do not adjust the frequency until after
* the stepout threshold.
*/
case EVNT_NSET:
adj_systime(fp_offset);
rstclock(EVNT_FREQ, fp_offset);
break;
/*
* In FREQ state ignore updates until the stepout
* threshold. After that, compute the new frequency, but
* do not adjust the frequency until the holdoff counter
* decrements to zero.
*/
case EVNT_FREQ:
if (mu < clock_minstep)
return (0);
clock_frequency = direct_freq(fp_offset);
/* fall through */
/*
* We get here by default in FSET, SPIK and SYNC states.
* Here compute the frequency update due to PLL and FLL
* contributions. Note, we avoid frequency discipline at
* startup until the initial transient has subsided.
*/
default:
allow_panic = FALSE;
if (freq_cnt == 0) {
/*
* The FLL and PLL frequency gain constants
* depend on the time constant and Allan
* intercept. The PLL is always used, but
* becomes ineffective above the Allan intercept
* where the FLL becomes effective.
*/
if (sys_poll >= allan_xpt)
clock_frequency += (fp_offset -
clock_offset) / max(ULOGTOD(sys_poll),
mu) * CLOCK_FLL;
/*
* The PLL frequency gain (numerator) depends on
* the minimum of the update interval and Allan
* intercept. This reduces the PLL gain when the
* FLL becomes effective.
*/
etemp = min(ULOGTOD(allan_xpt), mu);
dtemp = 4 * CLOCK_PLL * ULOGTOD(sys_poll);
clock_frequency += fp_offset * etemp / (dtemp *
dtemp);
}
rstclock(EVNT_SYNC, fp_offset);
if (fabs(fp_offset) < CLOCK_FLOOR)
freq_cnt = 0;
break;
}
}
#ifdef KERNEL_PLL
/*
* This code segment works when clock adjustments are made using
* precision time kernel support and the ntp_adjtime() system
* call. This support is available in Solaris 2.6 and later,
* Digital Unix 4.0 and later, FreeBSD, Linux and specially
* modified kernels for HP-UX 9 and Ultrix 4. In the case of the
* DECstation 5000/240 and Alpha AXP, additional kernel
* modifications provide a true microsecond clock and nanosecond
* clock, respectively.
*
* Important note: The kernel discipline is used only if the
* step threshold is less than 0.5 s, as anything higher can
* lead to overflow problems. This might occur if some misguided
* lad set the step threshold to something ridiculous.
*/
if (pll_control && kern_enable && freq_cnt == 0) {
/*
* We initialize the structure for the ntp_adjtime()
* system call. We have to convert everything to
* microseconds or nanoseconds first. Do not update the
* system variables if the ext_enable flag is set. In
* this case, the external clock driver will update the
* variables, which will be read later by the local
* clock driver. Afterwards, remember the time and
* frequency offsets for jitter and stability values and
* to update the frequency file.
*/
ZERO(ntv);
if (ext_enable) {
ntv.modes = MOD_STATUS;
} else {
#ifdef STA_NANO
ntv.modes = MOD_BITS | MOD_NANO;
#else /* STA_NANO */
ntv.modes = MOD_BITS;
#endif /* STA_NANO */
if (clock_offset < 0)
dtemp = -.5;
else
dtemp = .5;
#ifdef STA_NANO
ntv.offset = (int32)(clock_offset * 1e9 +
dtemp);
ntv.constant = sys_poll;
#else /* STA_NANO */
ntv.offset = (int32)(clock_offset * 1e6 +
dtemp);
ntv.constant = sys_poll - 4;
#endif /* STA_NANO */
if (ntv.constant < 0)
ntv.constant = 0;
ntv.esterror = (u_int32)(clock_jitter * 1e6);
ntv.maxerror = (u_int32)((sys_rootdelay / 2 +
sys_rootdisp) * 1e6);
ntv.status = STA_PLL;
/*
* Enable/disable the PPS if requested.
*/
if (hardpps_enable) {
ntv.status |= (STA_PPSTIME | STA_PPSFREQ);
if (!(pll_status & STA_PPSTIME))
sync_status("PPS enabled",
pll_status,
ntv.status);
} else {
ntv.status &= ~(STA_PPSTIME | STA_PPSFREQ);
if (pll_status & STA_PPSTIME)
sync_status("PPS disabled",
pll_status,
ntv.status);
}
if (sys_leap == LEAP_ADDSECOND)
ntv.status |= STA_INS;
else if (sys_leap == LEAP_DELSECOND)
ntv.status |= STA_DEL;
}
/*
* Pass the stuff to the kernel. If it squeals, turn off
* the pps. In any case, fetch the kernel offset,
* frequency and jitter.
*/
ntp_adj_ret = ntp_adjtime(&ntv);
/*
* A squeal is a return status < 0, or a state change.
*/
if ((0 > ntp_adj_ret) || (ntp_adj_ret != kernel_status)) {
kernel_status = ntp_adj_ret;
ntp_adjtime_error_handler(__func__, &ntv, ntp_adj_ret, errno, hardpps_enable, 0, __LINE__ - 1);
}
pll_status = ntv.status;
#ifdef STA_NANO
clock_offset = ntv.offset / 1e9;
#else /* STA_NANO */
clock_offset = ntv.offset / 1e6;
#endif /* STA_NANO */
clock_frequency = FREQTOD(ntv.freq);
/*
* If the kernel PPS is lit, monitor its performance.
*/
if (ntv.status & STA_PPSTIME) {
#ifdef STA_NANO
clock_jitter = ntv.jitter / 1e9;
#else /* STA_NANO */
clock_jitter = ntv.jitter / 1e6;
#endif /* STA_NANO */
}
#if defined(STA_NANO) && NTP_API == 4
/*
* If the TAI changes, update the kernel TAI.
*/
if (loop_tai != sys_tai) {
loop_tai = sys_tai;
ntv.modes = MOD_TAI;
ntv.constant = sys_tai;
if ((ntp_adj_ret = ntp_adjtime(&ntv)) != 0) {
ntp_adjtime_error_handler(__func__, &ntv, ntp_adj_ret, errno, 0, 1, __LINE__ - 1);
}
}
#endif /* STA_NANO */
}
#endif /* KERNEL_PLL */
/*
* Clamp the frequency within the tolerance range and calculate
* the frequency difference since the last update.
*/
if (fabs(clock_frequency) > NTP_MAXFREQ)
msyslog(LOG_NOTICE,
"frequency error %.0f PPM exceeds tolerance %.0f PPM",
clock_frequency * 1e6, NTP_MAXFREQ * 1e6);
dtemp = SQUARE(clock_frequency - drift_comp);
if (clock_frequency > NTP_MAXFREQ)
drift_comp = NTP_MAXFREQ;
else if (clock_frequency < -NTP_MAXFREQ)
drift_comp = -NTP_MAXFREQ;
else
drift_comp = clock_frequency;
/*
* Calculate the wander as the exponentially weighted RMS
* frequency differences. Record the change for the frequency
* file update.
*/
etemp = SQUARE(clock_stability);
clock_stability = SQRT(etemp + (dtemp - etemp) / CLOCK_AVG);
/*
* Here we adjust the time constant by comparing the current
* offset with the clock jitter. If the offset is less than the
* clock jitter times a constant, then the averaging interval is
* increased, otherwise it is decreased. A bit of hysteresis
* helps calm the dance. Works best using burst mode. Don't
* fiddle with the poll during the startup clamp period.
*/
if (freq_cnt > 0) {
tc_counter = 0;
} else if (fabs(clock_offset) < CLOCK_PGATE * clock_jitter) {
tc_counter += sys_poll;
if (tc_counter > CLOCK_LIMIT) {
tc_counter = CLOCK_LIMIT;
if (sys_poll < peer->maxpoll) {
tc_counter = 0;
sys_poll++;
}
}
} else {
tc_counter -= sys_poll << 1;
if (tc_counter < -CLOCK_LIMIT) {
tc_counter = -CLOCK_LIMIT;
if (sys_poll > peer->minpoll) {
tc_counter = 0;
sys_poll--;
}
}
}
/*
* If the time constant has changed, update the poll variables.
*/
if (osys_poll != sys_poll)
poll_update(peer, sys_poll);
/*
* Yibbidy, yibbbidy, yibbidy; that'h all folks.
*/
record_loop_stats(clock_offset, drift_comp, clock_jitter,
clock_stability, sys_poll);
#ifdef DEBUG
if (debug)
printf(
"local_clock: offset %.9f jit %.9f freq %.3f stab %.3f poll %d\n",
clock_offset, clock_jitter, drift_comp * 1e6,
clock_stability * 1e6, sys_poll);
#endif /* DEBUG */
return (rval);
#endif /* LOCKCLOCK */
}
/*
* adj_host_clock - Called once every second to update the local clock.
*
* LOCKCLOCK: The only thing this routine does is increment the
* sys_rootdisp variable.
*/
void
adj_host_clock(
void
)
{
double offset_adj;
double freq_adj;
/*
* Update the dispersion since the last update. In contrast to
* NTPv3, NTPv4 does not declare unsynchronized after one day,
* since the dispersion check serves this function. Also,
* since the poll interval can exceed one day, the old test
* would be counterproductive. During the startup clamp period, the
* time constant is clamped at 2.
*/
sys_rootdisp += clock_phi;
#ifndef LOCKCLOCK
if (!ntp_enable || mode_ntpdate)
return;
/*
* Determine the phase adjustment. The gain factor (denominator)
* increases with poll interval, so is dominated by the FLL
* above the Allan intercept. Note the reduced time constant at
* startup.
*/
if (state != EVNT_SYNC) {
offset_adj = 0.;
} else if (freq_cnt > 0) {
offset_adj = clock_offset / (CLOCK_PLL * ULOGTOD(1));
freq_cnt--;
#ifdef KERNEL_PLL
} else if (pll_control && kern_enable) {
offset_adj = 0.;
#endif /* KERNEL_PLL */
} else {
offset_adj = clock_offset / (CLOCK_PLL * ULOGTOD(sys_poll));
}
/*
* If the kernel discipline is enabled the frequency correction
* drift_comp has already been engaged via ntp_adjtime() in
* set_freq(). Otherwise it is a component of the adj_systime()
* offset.
*/
#ifdef KERNEL_PLL
if (pll_control && kern_enable)
freq_adj = 0.;
else
#endif /* KERNEL_PLL */
freq_adj = drift_comp;
/* Bound absolute value of total adjustment to NTP_MAXFREQ. */
if (offset_adj + freq_adj > NTP_MAXFREQ)
offset_adj = NTP_MAXFREQ - freq_adj;
else if (offset_adj + freq_adj < -NTP_MAXFREQ)
offset_adj = -NTP_MAXFREQ - freq_adj;
clock_offset -= offset_adj;
/*
* Windows port adj_systime() must be called each second,
* even if the argument is zero, to ease emulation of
* adjtime() using Windows' slew API which controls the rate
* but does not automatically stop slewing when an offset
* has decayed to zero.
*/
adj_systime(offset_adj + freq_adj);
#endif /* LOCKCLOCK */
}
