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/* $Id$ */
#ifndef _GPSD_TIMEBASE_H_
#define _GPSD_TIMEBASE_H_
/* timebase.h -- constants that will require patching over time */
/*
* The current (fixed) leap-second correction, and the future Unix
* time after which to start hunting leap-second corrections from GPS
* subframe data if the GPS doesn't supply them any more readily.
*
* Deferring the check is a hack to speed up fix acquisition --
* subframe data is bulky enough to substantially increase latency.
* To update LEAP_SECONDS and START_SUBFRAME, see the IERS leap-second
* bulletin page at:
* <http://hpiers.obspm.fr/eop-pc/products/bulletins/bulletins.html>
*
* You can use the Python expression
* time.mktime(time.strptime(... , "%d %b %Y %H:%M:%S"))
* to generate an integer value for START_SUBFRAME.
*/
/*
* This constant is used to get UTC from chipsets that report GPS time only.
*
* It's not a disaster if it's wrong; most such chips get the offset
* from some report abstracted from the subframe data, so their worst
* case is their time info will be incorrect for the remainder of an
* entire GPS message cycle (about 22 minutes) if you start gpsd up
* right after a leap-second.
*
* This value is only critical if the chipset gets GPS time only and
* not the offset; in this case gpsd will always report UTC that is exactly
* as incorrect as the constant. Currently this is true only for the
* Evermore chipset.
*/
#define LEAP_SECONDS 14
/* IERS says the next leap-second will be inserted at the end of 2008.
*/
#define START_SUBFRAME 1230785999 /* 31 Dec 2008 23:59:59 */
/*
* This is used only when an NMEA device issues a two-digit year in a GPRMC
* and there has been no previous ZDA to set the year. We used to
* query the system clock for this, but there's no good way to cope
* with the mess if the system clock has been zeroed.
*/
#define CENTURY_BASE 2000
/* timebase.h ends here */
#endif /* _GPSD_TIMEBASE_H_ */
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