/* * ntp_loopfilter.c - implements the NTP loop filter algorithm * * ATTENTION: Get approval from Dave Mills on all changes to this file! * */ #ifdef HAVE_CONFIG_H # include <config.h> #endif #include "ntpd.h" #include "ntp_io.h" #include "ntp_unixtime.h" #include "ntp_stdlib.h" #include <stdio.h> #include <ctype.h> #include <signal.h> #include <setjmp.h> #if defined(VMS) && defined(VMS_LOCALUNIT) /*wjm*/ #include "ntp_refclock.h" #endif /* VMS */ #ifdef KERNEL_PLL #include "ntp_syscall.h" #endif /* KERNEL_PLL */ /* * This is an implementation of the clock discipline algorithm described * in UDel TR 97-4-3, as amended. It operates as an adaptive parameter, * hybrid phase/frequency-lock loop. A number of sanity checks are * included to protect against timewarps, timespikes and general mayhem. * All units are in s and s/s, unless noted otherwise. */ #define CLOCK_MAX .128 /* default step threshold (s) */ #define CLOCK_MINSTEP 900. /* default stepout threshold (s) */ #define CLOCK_PANIC 1000. /* default panic threshold (s) */ #define CLOCK_PHI 15e-6 /* max frequency error (s/s) */ #define CLOCK_PLL 16. /* PLL loop gain (log2) */ #define CLOCK_AVG 8. /* parameter averaging constant */ #define CLOCK_FLL .25 /* FLL loop gain */ #define CLOCK_ALLAN 11 /* Allan intercept (log2 s) */ #define CLOCK_DAY 86400. /* one day in seconds (s) */ #define CLOCK_JUNE (CLOCK_DAY * 30) /* June in seconds (s) */ #define CLOCK_LIMIT 30 /* poll-adjust threshold */ #define CLOCK_PGATE 4. /* poll-adjust gate */ #define PPS_MAXAGE 120 /* kernel pps signal timeout (s) */ #define FREQTOD(x) ((x) / 65536e6) /* NTP to double */ #define DTOFREQ(x) ((int32)((x) * 65536e6)) /* double to NTP */ /* * Clock discipline state machine. This is used to control the * synchronization behavior during initialization and following a * timewarp. * * State < step > step Comments * ======================================================== * NSET FREQ step, FREQ freq not set * * FSET SYNC step, SYNC freq set * * FREQ if (mu < 900) if (mu < 900) set freq direct * ignore ignore * else else * freq, SYNC freq, step, SYNC * * SYNC SYNC SPIK, ignore adjust phase/freq * * SPIK SYNC if (mu < 900) adjust phase/freq * ignore * step, SYNC */ /* * Kernel PLL/PPS state machine. This is used with the kernel PLL * modifications described in the documentation. * * If kernel support for the ntp_adjtime() system call is available, the * ntp_control flag is set. The ntp_enable and kern_enable flags can be * set at configuration time or run time using ntpdc. If ntp_enable is * false, the discipline loop is unlocked and no corrections of any kind * are made. If both ntp_control and kern_enable are set, the kernel * support is used as described above; if false, the kernel is bypassed * entirely and the daemon discipline used instead. * * There have been three versions of the kernel discipline code. The * first (microkernel) now in Solaris discipilnes the microseconds. The * second and third (nanokernel) disciplines the clock in nanoseconds. * These versions are identifed if the symbol STA_PLL is present in the * header file /usr/include/sys/timex.h. The third and current version * includes TAI offset and is identified by the symbol NTP_API with * value 4. * * Each PPS time/frequency discipline can be enabled by the atom driver * or another driver. If enabled, the STA_PPSTIME and STA_FREQ bits are * set in the kernel status word; otherwise, these bits are cleared. * These bits are also cleard if the kernel reports an error. * * If an external clock is present, the clock driver sets STA_CLK in the * status word. When the local clock driver sees this bit, it updates * via this routine, which then calls ntp_adjtime() with the STA_PLL bit * set to zero, in which case the system clock is not adjusted. This is * also a signal for the external clock driver to discipline the system * clock. Unless specified otherwise, all times are in seconds. */ /* * Program variables that can be tinkered. */ double clock_max = CLOCK_MAX; /* step threshold */ double clock_minstep = CLOCK_MINSTEP; /* stepout threshold */ double clock_panic = CLOCK_PANIC; /* panic threshold */ double clock_phi = CLOCK_PHI; /* dispersion rate (s/s) */ u_char allan_xpt = CLOCK_ALLAN; /* Allan intercept (log2 s) */ /* * Program variables */ static double clock_offset; /* offset */ double clock_jitter; /* offset jitter */ double drift_comp; /* frequency (s/s) */ double clock_stability; /* frequency stability (wander) (s/s) */ double clock_codec; /* audio codec frequency (samples/s) */ static u_long clock_epoch; /* last update */ u_int sys_tai; /* TAI offset from UTC */ static void rstclock (int, double); /* transition function */ static double direct_freq(double); /* direct set frequency */ static void set_freq(double); /* set frequency */ #ifdef KERNEL_PLL static struct timex ntv; /* ntp_adjtime() parameters */ int pll_status; /* last kernel status bits */ #if defined(STA_NANO) && NTP_API == 4 static u_int loop_tai; /* last TAI offset */ #endif /* STA_NANO */ #endif /* KERNEL_PLL */ /* * Clock state machine control flags */ int ntp_enable = 1; /* clock discipline enabled */ int pll_control; /* kernel support available */ int kern_enable = 1; /* kernel support enabled */ int pps_enable; /* kernel PPS discipline enabled */ int ext_enable; /* external clock enabled */ int pps_stratum; /* pps stratum */ int allow_panic = FALSE; /* allow panic correction */ int mode_ntpdate = FALSE; /* exit on first clock set */ /* * Clock state machine variables */ int state; /* clock discipline state */ u_char sys_poll; /* time constant/poll (log2 s) */ int tc_counter; /* jiggle counter */ double last_offset; /* last offset (s) */ static u_long last_step; /* last clock step */ /* * Huff-n'-puff filter variables */ static double *sys_huffpuff; /* huff-n'-puff filter */ static int sys_hufflen; /* huff-n'-puff filter stages */ static int sys_huffptr; /* huff-n'-puff filter pointer */ static double sys_mindly; /* huff-n'-puff filter min delay */ #if defined(KERNEL_PLL) /* Emacs cc-mode goes nuts if we split the next line... */ #define MOD_BITS (MOD_OFFSET | MOD_MAXERROR | MOD_ESTERROR | \ MOD_STATUS | MOD_TIMECONST) #ifdef SIGSYS static void pll_trap (int); /* configuration trap */ static struct sigaction sigsys; /* current sigaction status */ static struct sigaction newsigsys; /* new sigaction status */ static sigjmp_buf env; /* environment var. for pll_trap() */ #endif /* SIGSYS */ #endif /* KERNEL_PLL */ /* * init_loopfilter - initialize loop filter data */ void init_loopfilter(void) { /* * Initialize state variables. */ sys_poll = ntp_minpoll; clock_jitter = LOGTOD(sys_precision); } /* * 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 */ 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 return (0); #else /* LOCKCLOCK */ if (!ntp_enable) { record_loop_stats(fp_offset, drift_comp, clock_jitter, clock_stability, sys_poll); return (0); } /* * 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. Othewise, 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 (fabs(fp_offset) > clock_max && clock_max > 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 (fabs(fp_offset) > clock_max && clock_max > 0) { switch (state) { /* * In SYNC state we ignore the first outlyer amd switch * to SPIK state. */ case EVNT_SYNC: snprintf(tbuf, sizeof(tbuf), "%+.6f s", fp_offset); report_event(EVNT_SPIK, NULL, tbuf); state = EVNT_SPIK; msyslog(LOG_NOTICE, "SYNC state ignoring %+.6f s", fp_offset); 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) { msyslog(LOG_NOTICE, "FREQ state ignoring %+.6f s", fp_offset); return (0); } clock_frequency = direct_freq(fp_offset); /* fall through to S_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) { msyslog(LOG_NOTICE, "SPIK state ignoring %+.6f s", fp_offset); 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); msyslog(LOG_NOTICE, "ntpd: time set %+.6f s", fp_offset); reinit_timer(); tc_counter = 0; clock_jitter = LOGTOD(sys_precision); rval = 2; if (state == EVNT_NSET || (current_time - last_step) < clock_minstep * 2) { rstclock(EVNT_FREQ, 0); return (rval); } last_step = current_time; 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: rstclock(EVNT_FREQ, fp_offset); break; /* * In FSET state this is the first update received and * the frequency has been initialized. Adjust the phase, * but do not adjust the frequency until the next * update. */ case EVNT_FSET: rstclock(EVNT_SYNC, fp_offset); break; /* * In FREQ state ignore updates until the stepout * threshold. After that, compute the new frequency, but * do not adjust the phase or frequency until the next * update. */ case EVNT_FREQ: if (mu < clock_minstep) { msyslog(LOG_NOTICE, "FREQ state ignoring %+.6f s", fp_offset); return (0); } clock_frequency = direct_freq(fp_offset); rstclock(EVNT_SYNC, 0); break; /* * We get here by default in SYNC and SPIK states. Here * we compute the frequency update due to PLL and FLL * contributions. */ default: allow_panic = FALSE; /* * 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); 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) { /* * 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. */ memset(&ntv, 0, sizeof(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 */ 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 (pps_enable) { if (!(pll_status & STA_PPSTIME)) report_event(EVNT_KERN, NULL, "PPS enabled"); ntv.status |= STA_PPSTIME | STA_PPSFREQ; } else { if (pll_status & STA_PPSTIME) report_event(EVNT_KERN, NULL, "PPS disabled"); ntv.status &= ~(STA_PPSTIME | STA_PPSFREQ); } 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. */ if (ntp_adjtime(&ntv) == TIME_ERROR) { if (!(ntv.status & STA_PPSSIGNAL)) report_event(EVNT_KERN, NULL, "PPS no signal"); } 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; ntp_adjtime(&ntv); } #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); drift_file_sw = TRUE; /* * Here we adjust the timeconstan 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. */ 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 adjustment; /* * 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. */ sys_rootdisp += clock_phi; #ifndef LOCKCLOCK /* * If clock discipline is disabled or if the kernel is enabled, * get out of Dodge quick. */ if (!ntp_enable || mode_ntpdate || (pll_control && kern_enable)) return; /* * Implement the phase and frequency adjustments. The gain * factor (denominator) increases with poll interval, so is * dominated by the FLL above the Allan intercept. */ adjustment = clock_offset / (CLOCK_PLL * ULOGTOD(sys_poll)); clock_offset -= adjustment; adj_systime(adjustment + drift_comp); #endif /* LOCKCLOCK */ } /* * Clock state machine. Enter new state and set state variables. */ static void rstclock( int trans, /* new state */ double offset /* new offset */ ) { #ifdef DEBUG if (debug > 1) printf("local_clock: mu %lu state %d poll %d count %d\n", current_time - clock_epoch, trans, sys_poll, tc_counter); #endif if (trans != state && trans != EVNT_FSET) report_event(trans, NULL, NULL); state = trans; last_offset = clock_offset = offset; clock_epoch = current_time; } /* * calc_freq - calculate frequency directly * * This is very carefully done. When the offset is first computed at the * first update, a residual frequency component results. Subsequently, * updates are suppresed until the end of the measurement interval while * the offset is amortized. At the end of the interval the frequency is * calculated from the current offset, residual offset, length of the * interval and residual frequency component. At the same time the * frequenchy file is armed for update at the next hourly stats. */ static double direct_freq( double fp_offset ) { #ifdef KERNEL_PLL /* * If the kernel is enabled, we need the residual offset to * calculate the frequency correction. */ if (pll_control && kern_enable) { memset(&ntv, 0, sizeof(ntv)); ntp_adjtime(&ntv); #ifdef STA_NANO clock_offset = ntv.offset / 1e9; #else /* STA_NANO */ clock_offset = ntv.offset / 1e6; #endif /* STA_NANO */ drift_comp = FREQTOD(ntv.freq); } #endif /* KERNEL_PLL */ set_freq((fp_offset - clock_offset) / (current_time - clock_epoch) + drift_comp); wander_resid = 0; return (drift_comp); } /* * set_freq - set clock frequency */ static void set_freq( double freq /* frequency update */ ) { char tbuf[80]; drift_comp = freq; #ifdef KERNEL_PLL /* * If the kernel is enabled, update the kernel frequency. */ if (pll_control && kern_enable) { memset(&ntv, 0, sizeof(ntv)); ntv.modes = MOD_FREQUENCY; ntv.freq = DTOFREQ(drift_comp); ntp_adjtime(&ntv); snprintf(tbuf, sizeof(tbuf), "kernel %.3f PPM", drift_comp * 1e6); report_event(EVNT_FSET, NULL, tbuf); } else { snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6); report_event(EVNT_FSET, NULL, tbuf); } #else /* KERNEL_PLL */ snprintf(tbuf, sizeof(tbuf), "ntpd %.3f PPM", drift_comp * 1e6); report_event(EVNT_FSET, NULL, tbuf); #endif /* KERNEL_PLL */ } /* * huff-n'-puff filter */ void huffpuff() { int i; if (sys_huffpuff == NULL) return; sys_huffptr = (sys_huffptr + 1) % sys_hufflen; sys_huffpuff[sys_huffptr] = 1e9; sys_mindly = 1e9; for (i = 0; i < sys_hufflen; i++) { if (sys_huffpuff[i] < sys_mindly) sys_mindly = sys_huffpuff[i]; } } /* * loop_config - configure the loop filter * * LOCKCLOCK: The LOOP_DRIFTINIT and LOOP_DRIFTCOMP cases are no-ops. */ void loop_config( int item, double freq ) { int i; #ifdef DEBUG if (debug > 1) printf("loop_config: item %d freq %f\n", item, freq); #endif switch (item) { /* * We first assume the kernel supports the ntp_adjtime() * syscall. If that syscall works, initialize the kernel time * variables. Otherwise, continue leaving no harm behind. */ case LOOP_DRIFTINIT: #ifndef LOCKCLOCK #ifdef KERNEL_PLL if (mode_ntpdate) break; pll_control = 1; memset(&ntv, 0, sizeof(ntv)); ntv.modes = MOD_BITS; ntv.status = STA_PLL; ntv.maxerror = MAXDISPERSE; ntv.esterror = MAXDISPERSE; ntv.constant = sys_poll; #ifdef SIGSYS /* * Use sigsetjmp() to save state and then call * ntp_adjtime(); if it fails, then siglongjmp() is used * to return control */ newsigsys.sa_handler = pll_trap; newsigsys.sa_flags = 0; if (sigaction(SIGSYS, &newsigsys, &sigsys)) { msyslog(LOG_ERR, "sigaction() fails to save SIGSYS trap: %m"); pll_control = 0; } if (sigsetjmp(env, 1) == 0) ntp_adjtime(&ntv); if ((sigaction(SIGSYS, &sigsys, (struct sigaction *)NULL))) { msyslog(LOG_ERR, "sigaction() fails to restore SIGSYS trap: %m"); pll_control = 0; } #else /* SIGSYS */ ntp_adjtime(&ntv); #endif /* SIGSYS */ /* * Save the result status and light up an external clock * if available. */ pll_status = ntv.status; if (pll_control) { #ifdef STA_NANO if (pll_status & STA_CLK) ext_enable = 1; #endif /* STA_NANO */ report_event(EVNT_KERN, NULL, "kernel time sync enabled"); } #endif /* KERNEL_PLL */ #endif /* LOCKCLOCK */ break; /* * Initialize the frequency. If the frequency file is missing or * broken, set the initial frequency to zero and set the state * to NSET. Otherwise, set the initial frequency to the given * value and the state to FSET. */ case LOOP_DRIFTCOMP: #ifndef LOCKCLOCK if (freq > NTP_MAXFREQ || freq < -NTP_MAXFREQ) { set_freq(0); rstclock(EVNT_NSET, 0); } else { set_freq(freq); rstclock(EVNT_FSET, 0); } #endif /* LOCKCLOCK */ break; /* * Disable the kernel at shutdown. The microkernel just abandons * ship. The nanokernel carefully cleans up so applications can * see this. Note the last programmed offset and frequency are * left in place. */ case LOOP_KERN_CLEAR: #ifndef LOCKCLOCK #ifdef KERNEL_PLL if (pll_control && kern_enable) { memset((char *)&ntv, 0, sizeof(ntv)); ntv.modes = MOD_STATUS; ntv.status = STA_UNSYNC; ntp_adjtime(&ntv); report_event(EVNT_KERN, NULL, "kernel time sync disabledx"); } #endif /* KERNEL_PLL */ #endif /* LOCKCLOCK */ break; /* * Tinker command variables for Ulrich Windl. Very dangerous. */ case LOOP_ALLAN: /* Allan intercept (log2) (allan) */ allan_xpt = (u_char)freq; break; case LOOP_CODEC: /* audio codec frequency (codec) */ clock_codec = freq / 1e6; break; case LOOP_PHI: /* dispersion threshold (dispersion) */ clock_phi = freq / 1e6; break; case LOOP_FREQ: /* initial frequency (freq) */ set_freq(freq / 1e6); rstclock(EVNT_FSET, 0); break; case LOOP_HUFFPUFF: /* huff-n'-puff length (huffpuff) */ if (freq < HUFFPUFF) freq = HUFFPUFF; sys_hufflen = (int)(freq / HUFFPUFF); sys_huffpuff = (double *)emalloc(sizeof(double) * sys_hufflen); for (i = 0; i < sys_hufflen; i++) sys_huffpuff[i] = 1e9; sys_mindly = 1e9; break; case LOOP_PANIC: /* panic threshold (panic) */ clock_panic = freq; break; case LOOP_MAX: /* step threshold (step) */ clock_max = freq; if (clock_max == 0 || clock_max > 0.5) kern_enable = 0; break; case LOOP_MINSTEP: /* stepout threshold (stepout) */ clock_minstep = freq; break; case LOOP_LEAP: /* not used */ default: msyslog(LOG_NOTICE, "loop_config: unsupported option %d", item); } } #if defined(KERNEL_PLL) && defined(SIGSYS) /* * _trap - trap processor for undefined syscalls * * This nugget is called by the kernel when the SYS_ntp_adjtime() * syscall bombs because the silly thing has not been implemented in * the kernel. In this case the phase-lock loop is emulated by * the stock adjtime() syscall and a lot of indelicate abuse. */ static RETSIGTYPE pll_trap( int arg ) { pll_control = 0; siglongjmp(env, 1); } #endif /* KERNEL_PLL && SIGSYS */