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local.h
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local.h
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/*
chronyd/chronyc - Programs for keeping computer clocks accurate.
**********************************************************************
* Copyright (C) Richard P. Curnow 1997-2002
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
**********************************************************************
=======================================================================
This module provides an interface to the system time, and
insulates the rest of the program from the different way
that interface has to be done on various operating systems.
*/
#ifndef GOT_LOCAL_H
#define GOT_LOCAL_H
#include "sysincl.h"
/* Read the system clock */
extern void LCL_ReadRawTime(struct timespec *ts);
/* Read the system clock, corrected according to all accumulated
drifts and uncompensated offsets.
In a kernel implementation with vernier frequency control (like
Linux), and if we were to apply offsets by stepping the clock, this
would be identical to raw time. In any other case (use of
adjtime()-like interface to correct offsets, and to adjust the
frequency), we must correct the raw time to get this value */
extern void LCL_ReadCookedTime(struct timespec *ts, double *err);
/* Convert raw time to cooked. */
extern void LCL_CookTime(struct timespec *raw, struct timespec *cooked, double *err);
/* Read the current offset between the system clock and true time
(i.e. 'cooked' - 'raw') (in seconds). */
extern void LCL_GetOffsetCorrection(struct timespec *raw, double *correction, double *err);
/* Type of routines that may be invoked as callbacks when there is a
change to the frequency or offset.
raw : raw local clock time at which change occurred
cooked : cooked local time at which change occurred
dfreq : delta frequency relative to previous value (in terms of
seconds gained by system clock per unit system clock time)
doffset : delta offset applied (positive => make local system fast
by that amount, negative => make it slow by that amount)
change_type : what type of change is being applied
anything : Passthrough argument from call to registration routine */
typedef enum {
LCL_ChangeAdjust,
LCL_ChangeStep,
LCL_ChangeUnknownStep
} LCL_ChangeType;
typedef void (*LCL_ParameterChangeHandler)
(struct timespec *raw, struct timespec *cooked,
double dfreq,
double doffset,
LCL_ChangeType change_type,
void *anything
);
/* Add a handler. Then handler MUST NOT deregister itself!!! */
extern void LCL_AddParameterChangeHandler(LCL_ParameterChangeHandler handler, void *anything);
/* Remove a handler */
extern void LCL_RemoveParameterChangeHandler(LCL_ParameterChangeHandler, void *anything);
/* Check if a handler is invoked first when dispatching */
extern int LCL_IsFirstParameterChangeHandler(LCL_ParameterChangeHandler handler);
/* Function type for handlers to be called back when an indeterminate
offset is introduced into the local time. This situation occurs
when the frequency must be adjusted to effect a clock slew and
there is doubt about one of the endpoints of the interval over
which the frequency change was applied.It is expected that such
handlers will add extra dispersion to any existing samples stored
in their registers.
dispersion : The bound on how much error has been introduced in the
local clock, in seconds.
anything : passthrough from the registration routine
*/
typedef void (*LCL_DispersionNotifyHandler)(double dispersion, void *anything);
/* Register a handler for being notified of dispersion being added to
the local clock. The handler MUST NOT unregister itself!!! */
extern void LCL_AddDispersionNotifyHandler(LCL_DispersionNotifyHandler handler, void *anything);
/* Delete a handler */
extern void LCL_RemoveDispersionNotifyHandler(LCL_DispersionNotifyHandler handler, void *anything);
/* Read the absolute system frequency, relative to the uncompensated
system. Returned in units of parts per million. Thus the result of
this is how many seconds fast the uncompensated system would be after
its own time has reached 1 million seconds from the start of the
measurement. */
extern double LCL_ReadAbsoluteFrequency(void);
/* Routine to set the absolute frequency. Only expected to be used
when either (i) reading the drift from a file at the start of a
run, or (ii) responsing to a user parameter 'poke'. This is
defined in ppm, as for the absolute frequency reading routine. */
extern void LCL_SetAbsoluteFrequency(double afreq);
/* Routine to apply a change of frequency to the local clock. The
argument is the estimated gain (positive) or loss (negative) of the
local clock relative to true time, per unit time of the PREVIOUS
frequency setting of the local clock. This is assumed to be based
on a regression of y=offset v x=cooked local time. */
extern void LCL_AccumulateDeltaFrequency(double dfreq);
/* Routine to apply an offset (in seconds) to the local clock. The
argument should be positive to move the clock backwards (i.e. the
local clock is currently fast of true time), or negative to move it
forwards (i.e. it is currently slow of true time). Provided is also
a suggested correction rate (correction time * offset). */
extern int LCL_AccumulateOffset(double offset, double corr_rate);
/* Routine to apply an immediate offset by doing a sudden step if
possible. (Intended for use after an initial estimate of offset has
been obtained, so that we don't end up using adjtime to achieve a
slew of an hour or something like that). A positive argument means
the system clock is fast on true time, i.e. it needs to be stepped
backwards. (Same convention as for AccumulateOffset routine). */
extern int LCL_ApplyStepOffset(double offset);
/* Routine to invoke notify handlers on an unexpected time jump
in system clock */
extern void LCL_NotifyExternalTimeStep(struct timespec *raw, struct timespec *cooked,
double offset, double dispersion);
/* Routine to invoke notify handlers on leap second when the system clock
doesn't correct itself */
extern void LCL_NotifyLeap(int leap);
/* Perform the combination of modifying the frequency and applying
a slew, in one easy step */
extern int LCL_AccumulateFrequencyAndOffset(double dfreq, double doffset, double corr_rate);
/* Same as the routine above, except it does not call the registered
parameter change handlers */
extern int LCL_AccumulateFrequencyAndOffsetNoHandlers(double dfreq, double doffset,
double corr_rate);
/* Routine to read the system precision as a log to base 2 value. */
extern int LCL_GetSysPrecisionAsLog(void);
/* Routine to read the system precision in terms of the actual time step */
extern double LCL_GetSysPrecisionAsQuantum(void);
/* Routine to read the maximum frequency error of the local clock. This
is a frequency stability, not an absolute error. */
extern double LCL_GetMaxClockError(void);
/* Routine to initialise the module (to be called once at program
start-up) */
extern void LCL_Initialise(void);
/* Routine to finalise the module (to be called once at end of
run). */
extern void LCL_Finalise(void);
/* Routine to convert the outstanding system clock error to a step and
apply it, e.g. if the system clock has ended up an hour wrong due
to a timezone problem. */
extern int LCL_MakeStep(void);
/* Routine to cancel the outstanding system clock correction */
extern void LCL_CancelOffsetCorrection(void);
/* Check if the system driver supports leap seconds, i.e. LCL_SetSystemLeap
does something */
extern int LCL_CanSystemLeap(void);
/* Routine to set the system clock to correct itself for a leap second and also
set its TAI-UTC offset. If supported, leap second will be inserted at the
end of the day if the argument is positive, deleted if negative, and zero
resets the setting. */
extern void LCL_SetSystemLeap(int leap, int tai_offset);
/* Routine to set a frequency correction (in ppm) that should be applied
to local clock to compensate for temperature changes. A positive
argument means that the clock frequency should be increased. Return the
actual compensation (may be different from the requested compensation
due to clamping or rounding). */
extern double LCL_SetTempComp(double comp);
/* Routine to update the synchronisation status in the kernel to allow other
applications to know if the system clock is synchronised and error bounds */
extern void LCL_SetSyncStatus(int synchronised, double est_error, double max_error);
#endif /* GOT_LOCAL_H */