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/**
* @file clockcheck.h
* @brief Implements clock sanity checking.
* @note Copyright (C) 2013 Miroslav Lichvar <mlichvar@redhat.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*/
#ifndef HAVE_CLOCKCHECK_H
#define HAVE_CLOCKCHECK_H
#include <stdint.h>
/** Opaque type */
struct clockcheck;
/**
* Create a new instance of a clock sanity check.
* @param freq_limit The maximum allowed frequency offset between uncorrected
* clock and the system monotonic clock in ppb.
* @return A pointer to a new clock check on success, NULL otherwise.
*/
struct clockcheck *clockcheck_create(int freq_limit);
/**
* Reset a clock check.
* @param cc Pointer to a clock check obtained via @ref clockcheck_create().
*/
void clockcheck_reset(struct clockcheck *cc);
/**
* Perform the sanity check on a time stamp.
* @param cc Pointer to a clock check obtained via @ref clockcheck_create().
* @param ts Time stamp made by the clock in nanoseconds.
* @return Zero if ts passed the check, non-zero otherwise.
*/
int clockcheck_sample(struct clockcheck *cc, uint64_t ts);
/**
* Inform clock check about changes in current frequency of the clock.
* @param cc Pointer to a clock check obtained via @ref clockcheck_create().
* @param freq Frequency correction applied to the clock in ppb.
*/
void clockcheck_set_freq(struct clockcheck *cc, int freq);
/**
* Check whether the frequency correction did not change unexpectedly.
* @param cc Pointer to a clock check obtained via @ref clockcheck_create().
* @param freq Current reading of the frequency correction in ppb.
* @return Zero if the frequency did not change, non-zero otherwise.
*/
int clockcheck_freq(struct clockcheck *cc, int freq);
/**
* Inform clock check that the clock was stepped.
* @param cc Pointer to a clock check obtained via @ref clockcheck_create().
* @param step Step correction applied to the clock in nanoseconds.
*/
void clockcheck_step(struct clockcheck *cc, int64_t step);
/**
* Destroy a clock check.
* @param cc Pointer to a clock check obtained via @ref clockcheck_create().
*/
void clockcheck_destroy(struct clockcheck *cc);
#endif
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