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/**
* @file lstab.h
* @note Copyright (C) 2012 Richard Cochran <richardcochran@gmail.com>
* @note SPDX-License-Identifier: GPL-2.0+
*/
#ifndef HAVE_LEAP_SECONDS_H
#define HAVE_LEAP_SECONDS_H
#include <stdint.h>
/** Opaque type */
struct lstab;
/**
* Creates an instance of a leap second table.
* @param filename File from which to initialize the table. If NULL or empty,
* the hard coded default table will be used.
* @return A pointer to a leap second table on success, NULL otherwise.
*/
struct lstab *lstab_create(const char *filename);
/**
* Updates an instance of a leap second table from the associated file.
* @param lstab Pointer to lstab to be updated.
* @return 0 if lstab is up to date, don't use a file or was successfully updated.
* non-zero - on error
*/
int update_leapsecond_table(struct lstab *lstab);
/**
* Destroys a leap second table instance.
* @param lstab A pointer obtained via lstab_create().
*/
void lstab_destroy(struct lstab *lstab);
/**
* Enumerates the possible result code for the lstab_utc2tai() method.
*/
enum lstab_result {
/**
* The given UTC value was found in the table, and the
* corresponding TAI time is utctime + tai_offset.
*/
LSTAB_OK,
/**
* The given UTC value is out of the range of the table, and
* the tai_offset return value is not set.
*/
LSTAB_UNKNOWN,
/**
* The given lstab is past its expiry date and the tai_offset return
* value may not be correct.
*/
LSTAB_EXPIRED,
/**
* The given UTC value is ambiguous. The corresponding TAI time is either
*
* utctime + tai_offset
* or
* utctime + tai_offset + 1.
*/
LSTAB_AMBIGUOUS,
};
/**
* Returns the TAI - UTC offset for a given UTC time value.
* @param lstab A pointer obtained via lstab_create().
* @param utctime The UTC time value of interest, in seconds.
* @param tai_offset Pointer to a buffer to hold the result.
* @return One of the lstab_result enumeration values.
*/
enum lstab_result lstab_utc2tai(struct lstab *lstab, uint64_t utctime,
int *tai_offset);
#endif
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