39c39
< * $Id: kern_clock.c,v 1.51 1998/01/11 00:44:27 phk Exp $
---
> * $Id: kern_clock.c,v 1.52 1998/01/11 19:07:58 phk Exp $
42,58d41
< /* Portions of this software are covered by the following: */
< /******************************************************************************
< * *
< * Copyright (c) David L. Mills 1993, 1994 *
< * *
< * Permission to use, copy, modify, and distribute this software and its *
< * documentation for any purpose and without fee is hereby granted, provided *
< * that the above copyright notice appears in all copies and that both the *
< * copyright notice and this permission notice appear in supporting *
< * documentation, and that the name University of Delaware not be used in *
< * advertising or publicity pertaining to distribution of the software *
< * without specific, written prior permission. The University of Delaware *
< * makes no representations about the suitability this software for any *
< * purpose. It is provided "as is" without express or implied warranty. *
< * *
< *****************************************************************************/
<
165,394d147
< * Phase/frequency-lock loop (PLL/FLL) definitions
< *
< * The following variables are read and set by the ntp_adjtime() system
< * call.
< *
< * time_state shows the state of the system clock, with values defined
< * in the timex.h header file.
< *
< * time_status shows the status of the system clock, with bits defined
< * in the timex.h header file.
< *
< * time_offset is used by the PLL/FLL to adjust the system time in small
< * increments.
< *
< * time_constant determines the bandwidth or "stiffness" of the PLL.
< *
< * time_tolerance determines maximum frequency error or tolerance of the
< * CPU clock oscillator and is a property of the architecture; however,
< * in principle it could change as result of the presence of external
< * discipline signals, for instance.
< *
< * time_precision is usually equal to the kernel tick variable; however,
< * in cases where a precision clock counter or external clock is
< * available, the resolution can be much less than this and depend on
< * whether the external clock is working or not.
< *
< * time_maxerror is initialized by a ntp_adjtime() call and increased by
< * the kernel once each second to reflect the maximum error
< * bound growth.
< *
< * time_esterror is set and read by the ntp_adjtime() call, but
< * otherwise not used by the kernel.
< */
< int time_status = STA_UNSYNC; /* clock status bits */
< int time_state = TIME_OK; /* clock state */
< long time_offset = 0; /* time offset (us) */
< long time_constant = 0; /* pll time constant */
< long time_tolerance = MAXFREQ; /* frequency tolerance (scaled ppm) */
< long time_precision = 1; /* clock precision (us) */
< long time_maxerror = MAXPHASE; /* maximum error (us) */
< long time_esterror = MAXPHASE; /* estimated error (us) */
<
< /*
< * The following variables establish the state of the PLL/FLL and the
< * residual time and frequency offset of the local clock. The scale
< * factors are defined in the timex.h header file.
< *
< * time_phase and time_freq are the phase increment and the frequency
< * increment, respectively, of the kernel time variable at each tick of
< * the clock.
< *
< * time_freq is set via ntp_adjtime() from a value stored in a file when
< * the synchronization daemon is first started. Its value is retrieved
< * via ntp_adjtime() and written to the file about once per hour by the
< * daemon.
< *
< * time_adj is the adjustment added to the value of tick at each timer
< * interrupt and is recomputed from time_phase and time_freq at each
< * seconds rollover.
< *
< * time_reftime is the second's portion of the system time on the last
< * call to ntp_adjtime(). It is used to adjust the time_freq variable
< * and to increase the time_maxerror as the time since last update
< * increases.
< */
< static long time_phase = 0; /* phase offset (scaled us) */
< long time_freq = 0; /* frequency offset (scaled ppm) */
< static long time_adj = 0; /* tick adjust (scaled 1 / hz) */
< static long time_reftime = 0; /* time at last adjustment (s) */
<
< #ifdef PPS_SYNC
< /*
< * The following variables are used only if the kernel PPS discipline
< * code is configured (PPS_SYNC). The scale factors are defined in the
< * timex.h header file.
< *
< * pps_time contains the time at each calibration interval, as read by
< * microtime(). pps_count counts the seconds of the calibration
< * interval, the duration of which is nominally pps_shift in powers of
< * two.
< *
< * pps_offset is the time offset produced by the time median filter
< * pps_tf[], while pps_jitter is the dispersion (jitter) measured by
< * this filter.
< *
< * pps_freq is the frequency offset produced by the frequency median
< * filter pps_ff[], while pps_stabil is the dispersion (wander) measured
< * by this filter.
< *
< * pps_usec is latched from a high resolution counter or external clock
< * at pps_time. Here we want the hardware counter contents only, not the
< * contents plus the time_tv.usec as usual.
< *
< * pps_valid counts the number of seconds since the last PPS update. It
< * is used as a watchdog timer to disable the PPS discipline should the
< * PPS signal be lost.
< *
< * pps_glitch counts the number of seconds since the beginning of an
< * offset burst more than tick/2 from current nominal offset. It is used
< * mainly to suppress error bursts due to priority conflicts between the
< * PPS interrupt and timer interrupt.
< *
< * pps_intcnt counts the calibration intervals for use in the interval-
< * adaptation algorithm. It's just too complicated for words.
< */
< struct timeval pps_time; /* kernel time at last interval */
< long pps_offset = 0; /* pps time offset (us) */
< long pps_jitter = MAXTIME; /* pps time dispersion (jitter) (us) */
< long pps_tf[] = {0, 0, 0}; /* pps time offset median filter (us) */
< long pps_freq = 0; /* frequency offset (scaled ppm) */
< long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */
< long pps_ff[] = {0, 0, 0}; /* frequency offset median filter */
< long pps_usec = 0; /* microsec counter at last interval */
< long pps_valid = PPS_VALID; /* pps signal watchdog counter */
< int pps_glitch = 0; /* pps signal glitch counter */
< int pps_count = 0; /* calibration interval counter (s) */
< int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */
< int pps_intcnt = 0; /* intervals at current duration */
<
< /*
< * PPS signal quality monitors
< *
< * pps_jitcnt counts the seconds that have been discarded because the
< * jitter measured by the time median filter exceeds the limit MAXTIME
< * (100 us).
< *
< * pps_calcnt counts the frequency calibration intervals, which are
< * variable from 4 s to 256 s.
< *
< * pps_errcnt counts the calibration intervals which have been discarded
< * because the wander exceeds the limit MAXFREQ (100 ppm) or where the
< * calibration interval jitter exceeds two ticks.
< *
< * pps_stbcnt counts the calibration intervals that have been discarded
< * because the frequency wander exceeds the limit MAXFREQ / 4 (25 us).
< */
< long pps_jitcnt = 0; /* jitter limit exceeded */
< long pps_calcnt = 0; /* calibration intervals */
< long pps_errcnt = 0; /* calibration errors */
< long pps_stbcnt = 0; /* stability limit exceeded */
< #endif /* PPS_SYNC */
<
< /* XXX none of this stuff works under FreeBSD */
<
< /*
< * hardupdate() - local clock update
< *
< * This routine is called by ntp_adjtime() to update the local clock
< * phase and frequency. The implementation is of an adaptive-parameter,
< * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
< * time and frequency offset estimates for each call. If the kernel PPS
< * discipline code is configured (PPS_SYNC), the PPS signal itself
< * determines the new time offset, instead of the calling argument.
< * Presumably, calls to ntp_adjtime() occur only when the caller
< * believes the local clock is valid within some bound (+-128 ms with
< * NTP). If the caller's time is far different than the PPS time, an
< * argument will ensue, and it's not clear who will lose.
< *
< * For uncompensated quartz crystal oscillatores and nominal update
< * intervals less than 1024 s, operation should be in phase-lock mode
< * (STA_FLL = 0), where the loop is disciplined to phase. For update
< * intervals greater than thiss, operation should be in frequency-lock
< * mode (STA_FLL = 1), where the loop is disciplined to frequency.
< *
< * Note: splclock() is in effect.
< */
< void
< hardupdate(offset)
< long offset;
< {
< long ltemp, mtemp;
<
< if (!(time_status & STA_PLL) && !(time_status & STA_PPSTIME))
< return;
< ltemp = offset;
< #ifdef PPS_SYNC
< if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
< ltemp = pps_offset;
< #endif /* PPS_SYNC */
<
< /*
< * Scale the phase adjustment and clamp to the operating range.
< */
< if (ltemp > MAXPHASE)
< time_offset = MAXPHASE << SHIFT_UPDATE;
< else if (ltemp < -MAXPHASE)
< time_offset = -(MAXPHASE << SHIFT_UPDATE);
< else
< time_offset = ltemp << SHIFT_UPDATE;
<
< /*
< * Select whether the frequency is to be controlled and in which
< * mode (PLL or FLL). Clamp to the operating range. Ugly
< * multiply/divide should be replaced someday.
< */
< if (time_status & STA_FREQHOLD || time_reftime == 0)
< time_reftime = time.tv_sec;
< mtemp = time.tv_sec - time_reftime;
< time_reftime = time.tv_sec;
< if (time_status & STA_FLL) {
< if (mtemp >= MINSEC) {
< ltemp = ((time_offset / mtemp) << (SHIFT_USEC -
< SHIFT_UPDATE));
< if (ltemp < 0)
< time_freq -= -ltemp >> SHIFT_KH;
< else
< time_freq += ltemp >> SHIFT_KH;
< }
< } else {
< if (mtemp < MAXSEC) {
< ltemp *= mtemp;
< if (ltemp < 0)
< time_freq -= -ltemp >> (time_constant +
< time_constant + SHIFT_KF -
< SHIFT_USEC);
< else
< time_freq += ltemp >> (time_constant +
< time_constant + SHIFT_KF -
< SHIFT_USEC);
< }
< }
< if (time_freq > time_tolerance)
< time_freq = time_tolerance;
< else if (time_freq < -time_tolerance)
< time_freq = -time_tolerance;
< }
<
<
<
< /*
427a181,183
> int time_update;
> struct timeval newtime = time;
> long ltemp;
459,462d214
< {
< int time_update;
< struct timeval newtime = time;
< long ltemp;
464,470c216,222
< if (timedelta == 0) {
< time_update = CPU_THISTICKLEN(tick);
< } else {
< time_update = CPU_THISTICKLEN(tick) + tickdelta;
< timedelta -= tickdelta;
< }
< BUMPTIME(&mono_time, time_update);
---
> if (timedelta == 0) {
> time_update = CPU_THISTICKLEN(tick);
> } else {
> time_update = CPU_THISTICKLEN(tick) + tickdelta;
> timedelta -= tickdelta;
> }
> BUMPTIME(&mono_time, time_update);
472,487c224,239
< /*
< * Compute the phase adjustment. If the low-order bits
< * (time_phase) of the update overflow, bump the high-order bits
< * (time_update).
< */
< time_phase += time_adj;
< if (time_phase <= -FINEUSEC) {
< ltemp = -time_phase >> SHIFT_SCALE;
< time_phase += ltemp << SHIFT_SCALE;
< time_update -= ltemp;
< }
< else if (time_phase >= FINEUSEC) {
< ltemp = time_phase >> SHIFT_SCALE;
< time_phase -= ltemp << SHIFT_SCALE;
< time_update += ltemp;
< }
---
> /*
> * Compute the phase adjustment. If the low-order bits
> * (time_phase) of the update overflow, bump the high-order bits
> * (time_update).
> */
> time_phase += time_adj;
> if (time_phase <= -FINEUSEC) {
> ltemp = -time_phase >> SHIFT_SCALE;
> time_phase += ltemp << SHIFT_SCALE;
> time_update -= ltemp;
> }
> else if (time_phase >= FINEUSEC) {
> ltemp = time_phase >> SHIFT_SCALE;
> time_phase -= ltemp << SHIFT_SCALE;
> time_update += ltemp;
> }
489,629c241,257
< newtime.tv_usec += time_update;
< /*
< * On rollover of the second the phase adjustment to be used for
< * the next second is calculated. Also, the maximum error is
< * increased by the tolerance. If the PPS frequency discipline
< * code is present, the phase is increased to compensate for the
< * CPU clock oscillator frequency error.
< *
< * On a 32-bit machine and given parameters in the timex.h
< * header file, the maximum phase adjustment is +-512 ms and
< * maximum frequency offset is a tad less than) +-512 ppm. On a
< * 64-bit machine, you shouldn't need to ask.
< */
< if (newtime.tv_usec >= 1000000) {
< newtime.tv_usec -= 1000000;
< newtime.tv_sec++;
< time_maxerror += time_tolerance >> SHIFT_USEC;
<
< /*
< * Compute the phase adjustment for the next second. In
< * PLL mode, the offset is reduced by a fixed factor
< * times the time constant. In FLL mode the offset is
< * used directly. In either mode, the maximum phase
< * adjustment for each second is clamped so as to spread
< * the adjustment over not more than the number of
< * seconds between updates.
< */
< if (time_offset < 0) {
< ltemp = -time_offset;
< if (!(time_status & STA_FLL))
< ltemp >>= SHIFT_KG + time_constant;
< if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
< ltemp = (MAXPHASE / MINSEC) <<
< SHIFT_UPDATE;
< time_offset += ltemp;
< time_adj = -ltemp << (SHIFT_SCALE - SHIFT_HZ -
< SHIFT_UPDATE);
< } else {
< ltemp = time_offset;
< if (!(time_status & STA_FLL))
< ltemp >>= SHIFT_KG + time_constant;
< if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
< ltemp = (MAXPHASE / MINSEC) <<
< SHIFT_UPDATE;
< time_offset -= ltemp;
< time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ -
< SHIFT_UPDATE);
< }
<
< /*
< * Compute the frequency estimate and additional phase
< * adjustment due to frequency error for the next
< * second. When the PPS signal is engaged, gnaw on the
< * watchdog counter and update the frequency computed by
< * the pll and the PPS signal.
< */
< #ifdef PPS_SYNC
< pps_valid++;
< if (pps_valid == PPS_VALID) {
< pps_jitter = MAXTIME;
< pps_stabil = MAXFREQ;
< time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
< STA_PPSWANDER | STA_PPSERROR);
< }
< ltemp = time_freq + pps_freq;
< #else
< ltemp = time_freq;
< #endif /* PPS_SYNC */
< if (ltemp < 0)
< time_adj -= -ltemp >>
< (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
< else
< time_adj += ltemp >>
< (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
<
< #if SHIFT_HZ == 7
< /*
< * When the CPU clock oscillator frequency is not a
< * power of two in Hz, the SHIFT_HZ is only an
< * approximate scale factor. In the SunOS kernel, this
< * results in a PLL gain factor of 1/1.28 = 0.78 what it
< * should be. In the following code the overall gain is
< * increased by a factor of 1.25, which results in a
< * residual error less than 3 percent.
< */
< /* Same thing applies for FreeBSD --GAW */
< if (hz == 100) {
< if (time_adj < 0)
< time_adj -= -time_adj >> 2;
< else
< time_adj += time_adj >> 2;
< }
< #endif /* SHIFT_HZ */
<
< /* XXX - this is really bogus, but can't be fixed until
< xntpd's idea of the system clock is fixed to know how
< the user wants leap seconds handled; in the mean time,
< we assume that users of NTP are running without proper
< leap second support (this is now the default anyway) */
< /*
< * Leap second processing. If in leap-insert state at
< * the end of the day, the system clock is set back one
< * second; if in leap-delete state, the system clock is
< * set ahead one second. The microtime() routine or
< * external clock driver will insure that reported time
< * is always monotonic. The ugly divides should be
< * replaced.
< */
< switch (time_state) {
<
< case TIME_OK:
< if (time_status & STA_INS)
< time_state = TIME_INS;
< else if (time_status & STA_DEL)
< time_state = TIME_DEL;
< break;
<
< case TIME_INS:
< if (newtime.tv_sec % 86400 == 0) {
< newtime.tv_sec--;
< time_state = TIME_OOP;
< }
< break;
<
< case TIME_DEL:
< if ((newtime.tv_sec + 1) % 86400 == 0) {
< newtime.tv_sec++;
< time_state = TIME_WAIT;
< }
< break;
<
< case TIME_OOP:
< time_state = TIME_WAIT;
< break;
<
< case TIME_WAIT:
< if (!(time_status & (STA_INS | STA_DEL)))
< time_state = TIME_OK;
< }
< }
< CPU_CLOCKUPDATE(&time, &newtime);
---
> newtime.tv_usec += time_update;
> /*
> * On rollover of the second the phase adjustment to be used for
> * the next second is calculated. Also, the maximum error is
> * increased by the tolerance. If the PPS frequency discipline
> * code is present, the phase is increased to compensate for the
> * CPU clock oscillator frequency error.
> *
> * On a 32-bit machine and given parameters in the timex.h
> * header file, the maximum phase adjustment is +-512 ms and
> * maximum frequency offset is a tad less than) +-512 ppm. On a
> * 64-bit machine, you shouldn't need to ask.
> */
> if (newtime.tv_usec >= 1000000) {
> newtime.tv_usec -= 1000000;
> newtime.tv_sec++;
> ntp_update_second(&newtime.tv_sec);
631,632c259,261
<
< if (TAILQ_FIRST(&callwheel[ticks & callwheelmask]) != NULL) {
---
> CPU_CLOCKUPDATE(&time, &newtime);
>
> if (TAILQ_FIRST(&callwheel[ticks & callwheelmask]) != NULL)
634d262
< }
903,1143d530
< #ifdef PPS_SYNC
<
< /* We need this ugly monster twice, so lets macroize it... */
<
< #define MEDIAN3(a, m, s) \
< do { \
< if (a[0] > a[1]) { \
< if (a[1] > a[2]) { \
< /* 0 1 2 */ \
< m = a[1]; \
< s = a[0] - a[2]; \
< } else if (a[2] > a[0]) { \
< /* 2 0 1 */ \
< m = a[0]; \
< s = a[2] - a[1]; \
< } else { \
< /* 0 2 1 */ \
< m = a[2]; \
< s = a[0] - a[1]; \
< } \
< } else { \
< if (a[1] < a[2]) { \
< /* 2 1 0 */ \
< m = a[1]; \
< s = a[2] - a[0]; \
< } else if (a[2] < a[0]) { \
< /* 1 0 2 */ \
< m = a[0]; \
< s = a[1] - a[2]; \
< } else { \
< /* 1 2 0 */ \
< m = a[2]; \
< s = a[1] - a[0]; \
< } \
< } \
< } while (0)
<
< /*
< * hardpps() - discipline CPU clock oscillator to external PPS signal
< *
< * This routine is called at each PPS interrupt in order to discipline
< * the CPU clock oscillator to the PPS signal. It measures the PPS phase
< * and leaves it in a handy spot for the hardclock() routine. It
< * integrates successive PPS phase differences and calculates the
< * frequency offset. This is used in hardclock() to discipline the CPU
< * clock oscillator so that intrinsic frequency error is cancelled out.
< * The code requires the caller to capture the time and hardware counter
< * value at the on-time PPS signal transition.
< *
< * Note that, on some Unix systems, this routine runs at an interrupt
< * priority level higher than the timer interrupt routine hardclock().
< * Therefore, the variables used are distinct from the hardclock()
< * variables, except for certain exceptions: The PPS frequency pps_freq
< * and phase pps_offset variables are determined by this routine and
< * updated atomically. The time_tolerance variable can be considered a
< * constant, since it is infrequently changed, and then only when the
< * PPS signal is disabled. The watchdog counter pps_valid is updated
< * once per second by hardclock() and is atomically cleared in this
< * routine.
< */
< void
< hardpps(tvp, p_usec)
< struct timeval *tvp; /* time at PPS */
< long p_usec; /* hardware counter at PPS */
< {
< long u_usec, v_usec, bigtick;
< long cal_sec, cal_usec;
<
< /*
< * An occasional glitch can be produced when the PPS interrupt
< * occurs in the hardclock() routine before the time variable is
< * updated. Here the offset is discarded when the difference
< * between it and the last one is greater than tick/2, but not
< * if the interval since the first discard exceeds 30 s.
< */
< time_status |= STA_PPSSIGNAL;
< time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
< pps_valid = 0;
< u_usec = -tvp->tv_usec;
< if (u_usec < -500000)
< u_usec += 1000000;
< v_usec = pps_offset - u_usec;
< if (v_usec < 0)
< v_usec = -v_usec;
< if (v_usec > (tick >> 1)) {
< if (pps_glitch > MAXGLITCH) {
< pps_glitch = 0;
< pps_tf[2] = u_usec;
< pps_tf[1] = u_usec;
< } else {
< pps_glitch++;
< u_usec = pps_offset;
< }
< } else
< pps_glitch = 0;
<
< /*
< * A three-stage median filter is used to help deglitch the pps
< * time. The median sample becomes the time offset estimate; the
< * difference between the other two samples becomes the time
< * dispersion (jitter) estimate.
< */
< pps_tf[2] = pps_tf[1];
< pps_tf[1] = pps_tf[0];
< pps_tf[0] = u_usec;
<
< MEDIAN3(pps_tf, pps_offset, v_usec);
<
< if (v_usec > MAXTIME)
< pps_jitcnt++;
< v_usec = (v_usec << PPS_AVG) - pps_jitter;
< if (v_usec < 0)
< pps_jitter -= -v_usec >> PPS_AVG;
< else
< pps_jitter += v_usec >> PPS_AVG;
< if (pps_jitter > (MAXTIME >> 1))
< time_status |= STA_PPSJITTER;
<
< /*
< * During the calibration interval adjust the starting time when
< * the tick overflows. At the end of the interval compute the
< * duration of the interval and the difference of the hardware
< * counters at the beginning and end of the interval. This code
< * is deliciously complicated by the fact valid differences may
< * exceed the value of tick when using long calibration
< * intervals and small ticks. Note that the counter can be
< * greater than tick if caught at just the wrong instant, but
< * the values returned and used here are correct.
< */
< bigtick = (long)tick << SHIFT_USEC;
< pps_usec -= pps_freq;
< if (pps_usec >= bigtick)
< pps_usec -= bigtick;
< if (pps_usec < 0)
< pps_usec += bigtick;
< pps_time.tv_sec++;
< pps_count++;
< if (pps_count < (1 << pps_shift))
< return;
< pps_count = 0;
< pps_calcnt++;
< u_usec = p_usec << SHIFT_USEC;
< v_usec = pps_usec - u_usec;
< if (v_usec >= bigtick >> 1)
< v_usec -= bigtick;
< if (v_usec < -(bigtick >> 1))
< v_usec += bigtick;
< if (v_usec < 0)
< v_usec = -(-v_usec >> pps_shift);
< else
< v_usec = v_usec >> pps_shift;
< pps_usec = u_usec;
< cal_sec = tvp->tv_sec;
< cal_usec = tvp->tv_usec;
< cal_sec -= pps_time.tv_sec;
< cal_usec -= pps_time.tv_usec;
< if (cal_usec < 0) {
< cal_usec += 1000000;
< cal_sec--;
< }
< pps_time = *tvp;
<
< /*
< * Check for lost interrupts, noise, excessive jitter and
< * excessive frequency error. The number of timer ticks during
< * the interval may vary +-1 tick. Add to this a margin of one
< * tick for the PPS signal jitter and maximum frequency
< * deviation. If the limits are exceeded, the calibration
< * interval is reset to the minimum and we start over.
< */
< u_usec = (long)tick << 1;
< if (!((cal_sec == -1 && cal_usec > (1000000 - u_usec))
< || (cal_sec == 0 && cal_usec < u_usec))
< || v_usec > time_tolerance || v_usec < -time_tolerance) {
< pps_errcnt++;
< pps_shift = PPS_SHIFT;
< pps_intcnt = 0;
< time_status |= STA_PPSERROR;
< return;
< }
<
< /*
< * A three-stage median filter is used to help deglitch the pps
< * frequency. The median sample becomes the frequency offset
< * estimate; the difference between the other two samples
< * becomes the frequency dispersion (stability) estimate.
< */
< pps_ff[2] = pps_ff[1];
< pps_ff[1] = pps_ff[0];
< pps_ff[0] = v_usec;
<
< MEDIAN3(pps_ff, u_usec, v_usec);
<
< /*
< * Here the frequency dispersion (stability) is updated. If it
< * is less than one-fourth the maximum (MAXFREQ), the frequency
< * offset is updated as well, but clamped to the tolerance. It
< * will be processed later by the hardclock() routine.
< */
< v_usec = (v_usec >> 1) - pps_stabil;
< if (v_usec < 0)
< pps_stabil -= -v_usec >> PPS_AVG;
< else
< pps_stabil += v_usec >> PPS_AVG;
< if (pps_stabil > MAXFREQ >> 2) {
< pps_stbcnt++;
< time_status |= STA_PPSWANDER;
< return;
< }
< if (time_status & STA_PPSFREQ) {
< if (u_usec < 0) {
< pps_freq -= -u_usec >> PPS_AVG;
< if (pps_freq < -time_tolerance)
< pps_freq = -time_tolerance;
< u_usec = -u_usec;
< } else {
< pps_freq += u_usec >> PPS_AVG;
< if (pps_freq > time_tolerance)
< pps_freq = time_tolerance;
< }
< }
<
< /*
< * Here the calibration interval is adjusted. If the maximum
< * time difference is greater than tick / 4, reduce the interval
< * by half. If this is not the case for four consecutive
< * intervals, double the interval.
< */
< if (u_usec << pps_shift > bigtick >> 2) {
< pps_intcnt = 0;
< if (pps_shift > PPS_SHIFT)
< pps_shift--;
< } else if (pps_intcnt >= 4) {
< pps_intcnt = 0;
< if (pps_shift < PPS_SHIFTMAX)
< pps_shift++;
< } else
< pps_intcnt++;
< }
< #endif /* PPS_SYNC */
<
< * $Id: kern_clock.c,v 1.51 1998/01/11 00:44:27 phk Exp $
---
> * $Id: kern_clock.c,v 1.52 1998/01/11 19:07:58 phk Exp $
42,58d41
< /* Portions of this software are covered by the following: */
< /******************************************************************************
< * *
< * Copyright (c) David L. Mills 1993, 1994 *
< * *
< * Permission to use, copy, modify, and distribute this software and its *
< * documentation for any purpose and without fee is hereby granted, provided *
< * that the above copyright notice appears in all copies and that both the *
< * copyright notice and this permission notice appear in supporting *
< * documentation, and that the name University of Delaware not be used in *
< * advertising or publicity pertaining to distribution of the software *
< * without specific, written prior permission. The University of Delaware *
< * makes no representations about the suitability this software for any *
< * purpose. It is provided "as is" without express or implied warranty. *
< * *
< *****************************************************************************/
<
165,394d147
< * Phase/frequency-lock loop (PLL/FLL) definitions
< *
< * The following variables are read and set by the ntp_adjtime() system
< * call.
< *
< * time_state shows the state of the system clock, with values defined
< * in the timex.h header file.
< *
< * time_status shows the status of the system clock, with bits defined
< * in the timex.h header file.
< *
< * time_offset is used by the PLL/FLL to adjust the system time in small
< * increments.
< *
< * time_constant determines the bandwidth or "stiffness" of the PLL.
< *
< * time_tolerance determines maximum frequency error or tolerance of the
< * CPU clock oscillator and is a property of the architecture; however,
< * in principle it could change as result of the presence of external
< * discipline signals, for instance.
< *
< * time_precision is usually equal to the kernel tick variable; however,
< * in cases where a precision clock counter or external clock is
< * available, the resolution can be much less than this and depend on
< * whether the external clock is working or not.
< *
< * time_maxerror is initialized by a ntp_adjtime() call and increased by
< * the kernel once each second to reflect the maximum error
< * bound growth.
< *
< * time_esterror is set and read by the ntp_adjtime() call, but
< * otherwise not used by the kernel.
< */
< int time_status = STA_UNSYNC; /* clock status bits */
< int time_state = TIME_OK; /* clock state */
< long time_offset = 0; /* time offset (us) */
< long time_constant = 0; /* pll time constant */
< long time_tolerance = MAXFREQ; /* frequency tolerance (scaled ppm) */
< long time_precision = 1; /* clock precision (us) */
< long time_maxerror = MAXPHASE; /* maximum error (us) */
< long time_esterror = MAXPHASE; /* estimated error (us) */
<
< /*
< * The following variables establish the state of the PLL/FLL and the
< * residual time and frequency offset of the local clock. The scale
< * factors are defined in the timex.h header file.
< *
< * time_phase and time_freq are the phase increment and the frequency
< * increment, respectively, of the kernel time variable at each tick of
< * the clock.
< *
< * time_freq is set via ntp_adjtime() from a value stored in a file when
< * the synchronization daemon is first started. Its value is retrieved
< * via ntp_adjtime() and written to the file about once per hour by the
< * daemon.
< *
< * time_adj is the adjustment added to the value of tick at each timer
< * interrupt and is recomputed from time_phase and time_freq at each
< * seconds rollover.
< *
< * time_reftime is the second's portion of the system time on the last
< * call to ntp_adjtime(). It is used to adjust the time_freq variable
< * and to increase the time_maxerror as the time since last update
< * increases.
< */
< static long time_phase = 0; /* phase offset (scaled us) */
< long time_freq = 0; /* frequency offset (scaled ppm) */
< static long time_adj = 0; /* tick adjust (scaled 1 / hz) */
< static long time_reftime = 0; /* time at last adjustment (s) */
<
< #ifdef PPS_SYNC
< /*
< * The following variables are used only if the kernel PPS discipline
< * code is configured (PPS_SYNC). The scale factors are defined in the
< * timex.h header file.
< *
< * pps_time contains the time at each calibration interval, as read by
< * microtime(). pps_count counts the seconds of the calibration
< * interval, the duration of which is nominally pps_shift in powers of
< * two.
< *
< * pps_offset is the time offset produced by the time median filter
< * pps_tf[], while pps_jitter is the dispersion (jitter) measured by
< * this filter.
< *
< * pps_freq is the frequency offset produced by the frequency median
< * filter pps_ff[], while pps_stabil is the dispersion (wander) measured
< * by this filter.
< *
< * pps_usec is latched from a high resolution counter or external clock
< * at pps_time. Here we want the hardware counter contents only, not the
< * contents plus the time_tv.usec as usual.
< *
< * pps_valid counts the number of seconds since the last PPS update. It
< * is used as a watchdog timer to disable the PPS discipline should the
< * PPS signal be lost.
< *
< * pps_glitch counts the number of seconds since the beginning of an
< * offset burst more than tick/2 from current nominal offset. It is used
< * mainly to suppress error bursts due to priority conflicts between the
< * PPS interrupt and timer interrupt.
< *
< * pps_intcnt counts the calibration intervals for use in the interval-
< * adaptation algorithm. It's just too complicated for words.
< */
< struct timeval pps_time; /* kernel time at last interval */
< long pps_offset = 0; /* pps time offset (us) */
< long pps_jitter = MAXTIME; /* pps time dispersion (jitter) (us) */
< long pps_tf[] = {0, 0, 0}; /* pps time offset median filter (us) */
< long pps_freq = 0; /* frequency offset (scaled ppm) */
< long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */
< long pps_ff[] = {0, 0, 0}; /* frequency offset median filter */
< long pps_usec = 0; /* microsec counter at last interval */
< long pps_valid = PPS_VALID; /* pps signal watchdog counter */
< int pps_glitch = 0; /* pps signal glitch counter */
< int pps_count = 0; /* calibration interval counter (s) */
< int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */
< int pps_intcnt = 0; /* intervals at current duration */
<
< /*
< * PPS signal quality monitors
< *
< * pps_jitcnt counts the seconds that have been discarded because the
< * jitter measured by the time median filter exceeds the limit MAXTIME
< * (100 us).
< *
< * pps_calcnt counts the frequency calibration intervals, which are
< * variable from 4 s to 256 s.
< *
< * pps_errcnt counts the calibration intervals which have been discarded
< * because the wander exceeds the limit MAXFREQ (100 ppm) or where the
< * calibration interval jitter exceeds two ticks.
< *
< * pps_stbcnt counts the calibration intervals that have been discarded
< * because the frequency wander exceeds the limit MAXFREQ / 4 (25 us).
< */
< long pps_jitcnt = 0; /* jitter limit exceeded */
< long pps_calcnt = 0; /* calibration intervals */
< long pps_errcnt = 0; /* calibration errors */
< long pps_stbcnt = 0; /* stability limit exceeded */
< #endif /* PPS_SYNC */
<
< /* XXX none of this stuff works under FreeBSD */
<
< /*
< * hardupdate() - local clock update
< *
< * This routine is called by ntp_adjtime() to update the local clock
< * phase and frequency. The implementation is of an adaptive-parameter,
< * hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
< * time and frequency offset estimates for each call. If the kernel PPS
< * discipline code is configured (PPS_SYNC), the PPS signal itself
< * determines the new time offset, instead of the calling argument.
< * Presumably, calls to ntp_adjtime() occur only when the caller
< * believes the local clock is valid within some bound (+-128 ms with
< * NTP). If the caller's time is far different than the PPS time, an
< * argument will ensue, and it's not clear who will lose.
< *
< * For uncompensated quartz crystal oscillatores and nominal update
< * intervals less than 1024 s, operation should be in phase-lock mode
< * (STA_FLL = 0), where the loop is disciplined to phase. For update
< * intervals greater than thiss, operation should be in frequency-lock
< * mode (STA_FLL = 1), where the loop is disciplined to frequency.
< *
< * Note: splclock() is in effect.
< */
< void
< hardupdate(offset)
< long offset;
< {
< long ltemp, mtemp;
<
< if (!(time_status & STA_PLL) && !(time_status & STA_PPSTIME))
< return;
< ltemp = offset;
< #ifdef PPS_SYNC
< if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
< ltemp = pps_offset;
< #endif /* PPS_SYNC */
<
< /*
< * Scale the phase adjustment and clamp to the operating range.
< */
< if (ltemp > MAXPHASE)
< time_offset = MAXPHASE << SHIFT_UPDATE;
< else if (ltemp < -MAXPHASE)
< time_offset = -(MAXPHASE << SHIFT_UPDATE);
< else
< time_offset = ltemp << SHIFT_UPDATE;
<
< /*
< * Select whether the frequency is to be controlled and in which
< * mode (PLL or FLL). Clamp to the operating range. Ugly
< * multiply/divide should be replaced someday.
< */
< if (time_status & STA_FREQHOLD || time_reftime == 0)
< time_reftime = time.tv_sec;
< mtemp = time.tv_sec - time_reftime;
< time_reftime = time.tv_sec;
< if (time_status & STA_FLL) {
< if (mtemp >= MINSEC) {
< ltemp = ((time_offset / mtemp) << (SHIFT_USEC -
< SHIFT_UPDATE));
< if (ltemp < 0)
< time_freq -= -ltemp >> SHIFT_KH;
< else
< time_freq += ltemp >> SHIFT_KH;
< }
< } else {
< if (mtemp < MAXSEC) {
< ltemp *= mtemp;
< if (ltemp < 0)
< time_freq -= -ltemp >> (time_constant +
< time_constant + SHIFT_KF -
< SHIFT_USEC);
< else
< time_freq += ltemp >> (time_constant +
< time_constant + SHIFT_KF -
< SHIFT_USEC);
< }
< }
< if (time_freq > time_tolerance)
< time_freq = time_tolerance;
< else if (time_freq < -time_tolerance)
< time_freq = -time_tolerance;
< }
<
<
<
< /*
427a181,183
> int time_update;
> struct timeval newtime = time;
> long ltemp;
459,462d214
< {
< int time_update;
< struct timeval newtime = time;
< long ltemp;
464,470c216,222
< if (timedelta == 0) {
< time_update = CPU_THISTICKLEN(tick);
< } else {
< time_update = CPU_THISTICKLEN(tick) + tickdelta;
< timedelta -= tickdelta;
< }
< BUMPTIME(&mono_time, time_update);
---
> if (timedelta == 0) {
> time_update = CPU_THISTICKLEN(tick);
> } else {
> time_update = CPU_THISTICKLEN(tick) + tickdelta;
> timedelta -= tickdelta;
> }
> BUMPTIME(&mono_time, time_update);
472,487c224,239
< /*
< * Compute the phase adjustment. If the low-order bits
< * (time_phase) of the update overflow, bump the high-order bits
< * (time_update).
< */
< time_phase += time_adj;
< if (time_phase <= -FINEUSEC) {
< ltemp = -time_phase >> SHIFT_SCALE;
< time_phase += ltemp << SHIFT_SCALE;
< time_update -= ltemp;
< }
< else if (time_phase >= FINEUSEC) {
< ltemp = time_phase >> SHIFT_SCALE;
< time_phase -= ltemp << SHIFT_SCALE;
< time_update += ltemp;
< }
---
> /*
> * Compute the phase adjustment. If the low-order bits
> * (time_phase) of the update overflow, bump the high-order bits
> * (time_update).
> */
> time_phase += time_adj;
> if (time_phase <= -FINEUSEC) {
> ltemp = -time_phase >> SHIFT_SCALE;
> time_phase += ltemp << SHIFT_SCALE;
> time_update -= ltemp;
> }
> else if (time_phase >= FINEUSEC) {
> ltemp = time_phase >> SHIFT_SCALE;
> time_phase -= ltemp << SHIFT_SCALE;
> time_update += ltemp;
> }
489,629c241,257
< newtime.tv_usec += time_update;
< /*
< * On rollover of the second the phase adjustment to be used for
< * the next second is calculated. Also, the maximum error is
< * increased by the tolerance. If the PPS frequency discipline
< * code is present, the phase is increased to compensate for the
< * CPU clock oscillator frequency error.
< *
< * On a 32-bit machine and given parameters in the timex.h
< * header file, the maximum phase adjustment is +-512 ms and
< * maximum frequency offset is a tad less than) +-512 ppm. On a
< * 64-bit machine, you shouldn't need to ask.
< */
< if (newtime.tv_usec >= 1000000) {
< newtime.tv_usec -= 1000000;
< newtime.tv_sec++;
< time_maxerror += time_tolerance >> SHIFT_USEC;
<
< /*
< * Compute the phase adjustment for the next second. In
< * PLL mode, the offset is reduced by a fixed factor
< * times the time constant. In FLL mode the offset is
< * used directly. In either mode, the maximum phase
< * adjustment for each second is clamped so as to spread
< * the adjustment over not more than the number of
< * seconds between updates.
< */
< if (time_offset < 0) {
< ltemp = -time_offset;
< if (!(time_status & STA_FLL))
< ltemp >>= SHIFT_KG + time_constant;
< if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
< ltemp = (MAXPHASE / MINSEC) <<
< SHIFT_UPDATE;
< time_offset += ltemp;
< time_adj = -ltemp << (SHIFT_SCALE - SHIFT_HZ -
< SHIFT_UPDATE);
< } else {
< ltemp = time_offset;
< if (!(time_status & STA_FLL))
< ltemp >>= SHIFT_KG + time_constant;
< if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
< ltemp = (MAXPHASE / MINSEC) <<
< SHIFT_UPDATE;
< time_offset -= ltemp;
< time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ -
< SHIFT_UPDATE);
< }
<
< /*
< * Compute the frequency estimate and additional phase
< * adjustment due to frequency error for the next
< * second. When the PPS signal is engaged, gnaw on the
< * watchdog counter and update the frequency computed by
< * the pll and the PPS signal.
< */
< #ifdef PPS_SYNC
< pps_valid++;
< if (pps_valid == PPS_VALID) {
< pps_jitter = MAXTIME;
< pps_stabil = MAXFREQ;
< time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
< STA_PPSWANDER | STA_PPSERROR);
< }
< ltemp = time_freq + pps_freq;
< #else
< ltemp = time_freq;
< #endif /* PPS_SYNC */
< if (ltemp < 0)
< time_adj -= -ltemp >>
< (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
< else
< time_adj += ltemp >>
< (SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
<
< #if SHIFT_HZ == 7
< /*
< * When the CPU clock oscillator frequency is not a
< * power of two in Hz, the SHIFT_HZ is only an
< * approximate scale factor. In the SunOS kernel, this
< * results in a PLL gain factor of 1/1.28 = 0.78 what it
< * should be. In the following code the overall gain is
< * increased by a factor of 1.25, which results in a
< * residual error less than 3 percent.
< */
< /* Same thing applies for FreeBSD --GAW */
< if (hz == 100) {
< if (time_adj < 0)
< time_adj -= -time_adj >> 2;
< else
< time_adj += time_adj >> 2;
< }
< #endif /* SHIFT_HZ */
<
< /* XXX - this is really bogus, but can't be fixed until
< xntpd's idea of the system clock is fixed to know how
< the user wants leap seconds handled; in the mean time,
< we assume that users of NTP are running without proper
< leap second support (this is now the default anyway) */
< /*
< * Leap second processing. If in leap-insert state at
< * the end of the day, the system clock is set back one
< * second; if in leap-delete state, the system clock is
< * set ahead one second. The microtime() routine or
< * external clock driver will insure that reported time
< * is always monotonic. The ugly divides should be
< * replaced.
< */
< switch (time_state) {
<
< case TIME_OK:
< if (time_status & STA_INS)
< time_state = TIME_INS;
< else if (time_status & STA_DEL)
< time_state = TIME_DEL;
< break;
<
< case TIME_INS:
< if (newtime.tv_sec % 86400 == 0) {
< newtime.tv_sec--;
< time_state = TIME_OOP;
< }
< break;
<
< case TIME_DEL:
< if ((newtime.tv_sec + 1) % 86400 == 0) {
< newtime.tv_sec++;
< time_state = TIME_WAIT;
< }
< break;
<
< case TIME_OOP:
< time_state = TIME_WAIT;
< break;
<
< case TIME_WAIT:
< if (!(time_status & (STA_INS | STA_DEL)))
< time_state = TIME_OK;
< }
< }
< CPU_CLOCKUPDATE(&time, &newtime);
---
> newtime.tv_usec += time_update;
> /*
> * On rollover of the second the phase adjustment to be used for
> * the next second is calculated. Also, the maximum error is
> * increased by the tolerance. If the PPS frequency discipline
> * code is present, the phase is increased to compensate for the
> * CPU clock oscillator frequency error.
> *
> * On a 32-bit machine and given parameters in the timex.h
> * header file, the maximum phase adjustment is +-512 ms and
> * maximum frequency offset is a tad less than) +-512 ppm. On a
> * 64-bit machine, you shouldn't need to ask.
> */
> if (newtime.tv_usec >= 1000000) {
> newtime.tv_usec -= 1000000;
> newtime.tv_sec++;
> ntp_update_second(&newtime.tv_sec);
631,632c259,261
<
< if (TAILQ_FIRST(&callwheel[ticks & callwheelmask]) != NULL) {
---
> CPU_CLOCKUPDATE(&time, &newtime);
>
> if (TAILQ_FIRST(&callwheel[ticks & callwheelmask]) != NULL)
634d262
< }
903,1143d530
< #ifdef PPS_SYNC
<
< /* We need this ugly monster twice, so lets macroize it... */
<
< #define MEDIAN3(a, m, s) \
< do { \
< if (a[0] > a[1]) { \
< if (a[1] > a[2]) { \
< /* 0 1 2 */ \
< m = a[1]; \
< s = a[0] - a[2]; \
< } else if (a[2] > a[0]) { \
< /* 2 0 1 */ \
< m = a[0]; \
< s = a[2] - a[1]; \
< } else { \
< /* 0 2 1 */ \
< m = a[2]; \
< s = a[0] - a[1]; \
< } \
< } else { \
< if (a[1] < a[2]) { \
< /* 2 1 0 */ \
< m = a[1]; \
< s = a[2] - a[0]; \
< } else if (a[2] < a[0]) { \
< /* 1 0 2 */ \
< m = a[0]; \
< s = a[1] - a[2]; \
< } else { \
< /* 1 2 0 */ \
< m = a[2]; \
< s = a[1] - a[0]; \
< } \
< } \
< } while (0)
<
< /*
< * hardpps() - discipline CPU clock oscillator to external PPS signal
< *
< * This routine is called at each PPS interrupt in order to discipline
< * the CPU clock oscillator to the PPS signal. It measures the PPS phase
< * and leaves it in a handy spot for the hardclock() routine. It
< * integrates successive PPS phase differences and calculates the
< * frequency offset. This is used in hardclock() to discipline the CPU
< * clock oscillator so that intrinsic frequency error is cancelled out.
< * The code requires the caller to capture the time and hardware counter
< * value at the on-time PPS signal transition.
< *
< * Note that, on some Unix systems, this routine runs at an interrupt
< * priority level higher than the timer interrupt routine hardclock().
< * Therefore, the variables used are distinct from the hardclock()
< * variables, except for certain exceptions: The PPS frequency pps_freq
< * and phase pps_offset variables are determined by this routine and
< * updated atomically. The time_tolerance variable can be considered a
< * constant, since it is infrequently changed, and then only when the
< * PPS signal is disabled. The watchdog counter pps_valid is updated
< * once per second by hardclock() and is atomically cleared in this
< * routine.
< */
< void
< hardpps(tvp, p_usec)
< struct timeval *tvp; /* time at PPS */
< long p_usec; /* hardware counter at PPS */
< {
< long u_usec, v_usec, bigtick;
< long cal_sec, cal_usec;
<
< /*
< * An occasional glitch can be produced when the PPS interrupt
< * occurs in the hardclock() routine before the time variable is
< * updated. Here the offset is discarded when the difference
< * between it and the last one is greater than tick/2, but not
< * if the interval since the first discard exceeds 30 s.
< */
< time_status |= STA_PPSSIGNAL;
< time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
< pps_valid = 0;
< u_usec = -tvp->tv_usec;
< if (u_usec < -500000)
< u_usec += 1000000;
< v_usec = pps_offset - u_usec;
< if (v_usec < 0)
< v_usec = -v_usec;
< if (v_usec > (tick >> 1)) {
< if (pps_glitch > MAXGLITCH) {
< pps_glitch = 0;
< pps_tf[2] = u_usec;
< pps_tf[1] = u_usec;
< } else {
< pps_glitch++;
< u_usec = pps_offset;
< }
< } else
< pps_glitch = 0;
<
< /*
< * A three-stage median filter is used to help deglitch the pps
< * time. The median sample becomes the time offset estimate; the
< * difference between the other two samples becomes the time
< * dispersion (jitter) estimate.
< */
< pps_tf[2] = pps_tf[1];
< pps_tf[1] = pps_tf[0];
< pps_tf[0] = u_usec;
<
< MEDIAN3(pps_tf, pps_offset, v_usec);
<
< if (v_usec > MAXTIME)
< pps_jitcnt++;
< v_usec = (v_usec << PPS_AVG) - pps_jitter;
< if (v_usec < 0)
< pps_jitter -= -v_usec >> PPS_AVG;
< else
< pps_jitter += v_usec >> PPS_AVG;
< if (pps_jitter > (MAXTIME >> 1))
< time_status |= STA_PPSJITTER;
<
< /*
< * During the calibration interval adjust the starting time when
< * the tick overflows. At the end of the interval compute the
< * duration of the interval and the difference of the hardware
< * counters at the beginning and end of the interval. This code
< * is deliciously complicated by the fact valid differences may
< * exceed the value of tick when using long calibration
< * intervals and small ticks. Note that the counter can be
< * greater than tick if caught at just the wrong instant, but
< * the values returned and used here are correct.
< */
< bigtick = (long)tick << SHIFT_USEC;
< pps_usec -= pps_freq;
< if (pps_usec >= bigtick)
< pps_usec -= bigtick;
< if (pps_usec < 0)
< pps_usec += bigtick;
< pps_time.tv_sec++;
< pps_count++;
< if (pps_count < (1 << pps_shift))
< return;
< pps_count = 0;
< pps_calcnt++;
< u_usec = p_usec << SHIFT_USEC;
< v_usec = pps_usec - u_usec;
< if (v_usec >= bigtick >> 1)
< v_usec -= bigtick;
< if (v_usec < -(bigtick >> 1))
< v_usec += bigtick;
< if (v_usec < 0)
< v_usec = -(-v_usec >> pps_shift);
< else
< v_usec = v_usec >> pps_shift;
< pps_usec = u_usec;
< cal_sec = tvp->tv_sec;
< cal_usec = tvp->tv_usec;
< cal_sec -= pps_time.tv_sec;
< cal_usec -= pps_time.tv_usec;
< if (cal_usec < 0) {
< cal_usec += 1000000;
< cal_sec--;
< }
< pps_time = *tvp;
<
< /*
< * Check for lost interrupts, noise, excessive jitter and
< * excessive frequency error. The number of timer ticks during
< * the interval may vary +-1 tick. Add to this a margin of one
< * tick for the PPS signal jitter and maximum frequency
< * deviation. If the limits are exceeded, the calibration
< * interval is reset to the minimum and we start over.
< */
< u_usec = (long)tick << 1;
< if (!((cal_sec == -1 && cal_usec > (1000000 - u_usec))
< || (cal_sec == 0 && cal_usec < u_usec))
< || v_usec > time_tolerance || v_usec < -time_tolerance) {
< pps_errcnt++;
< pps_shift = PPS_SHIFT;
< pps_intcnt = 0;
< time_status |= STA_PPSERROR;
< return;
< }
<
< /*
< * A three-stage median filter is used to help deglitch the pps
< * frequency. The median sample becomes the frequency offset
< * estimate; the difference between the other two samples
< * becomes the frequency dispersion (stability) estimate.
< */
< pps_ff[2] = pps_ff[1];
< pps_ff[1] = pps_ff[0];
< pps_ff[0] = v_usec;
<
< MEDIAN3(pps_ff, u_usec, v_usec);
<
< /*
< * Here the frequency dispersion (stability) is updated. If it
< * is less than one-fourth the maximum (MAXFREQ), the frequency
< * offset is updated as well, but clamped to the tolerance. It
< * will be processed later by the hardclock() routine.
< */
< v_usec = (v_usec >> 1) - pps_stabil;
< if (v_usec < 0)
< pps_stabil -= -v_usec >> PPS_AVG;
< else
< pps_stabil += v_usec >> PPS_AVG;
< if (pps_stabil > MAXFREQ >> 2) {
< pps_stbcnt++;
< time_status |= STA_PPSWANDER;
< return;
< }
< if (time_status & STA_PPSFREQ) {
< if (u_usec < 0) {
< pps_freq -= -u_usec >> PPS_AVG;
< if (pps_freq < -time_tolerance)
< pps_freq = -time_tolerance;
< u_usec = -u_usec;
< } else {
< pps_freq += u_usec >> PPS_AVG;
< if (pps_freq > time_tolerance)
< pps_freq = time_tolerance;
< }
< }
<
< /*
< * Here the calibration interval is adjusted. If the maximum
< * time difference is greater than tick / 4, reduce the interval
< * by half. If this is not the case for four consecutive
< * intervals, double the interval.
< */
< if (u_usec << pps_shift > bigtick >> 2) {
< pps_intcnt = 0;
< if (pps_shift > PPS_SHIFT)
< pps_shift--;
< } else if (pps_intcnt >= 4) {
< pps_intcnt = 0;
< if (pps_shift < PPS_SHIFTMAX)
< pps_shift++;
< } else
< pps_intcnt++;
< }
< #endif /* PPS_SYNC */
<