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util: add support for other NTP eras

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NTP timestamps use only 32 bits to count seconds and the current NTP era
ends in 2036. Add support for converting NTP timestamps from other NTP
eras on systems with 64-bit time_t.

The earliest assumed NTP time is set by the configure script (by default
to 50 years before the date of the build) and earlier NTP timestamps
underflow to the following NTP era.
This commit is contained in:
Miroslav Lichvar
2014-08-07 17:08:19 +02:00
parent cb88cea3c4
commit 474b2af1a6
3 changed files with 75 additions and 6 deletions
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23
util.c
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@@ -498,16 +498,17 @@ void
UTI_TimevalToInt64(struct timeval *src,
NTP_int64 *dest, uint32_t fuzz)
{
unsigned long usec = src->tv_usec;
unsigned long sec = src->tv_sec;
uint32_t lo;
uint32_t lo, sec, usec;
sec = (uint32_t)src->tv_sec;
usec = (uint32_t)src->tv_usec;
/* Recognize zero as a special case - it always signifies
an 'unknown' value */
if (!usec && !sec) {
dest->hi = dest->lo = 0;
} else {
dest->hi = htonl(src->tv_sec + JAN_1970);
dest->hi = htonl(sec + JAN_1970);
/* This formula gives an error of about 0.1us worst case */
lo = 4295 * usec - (usec>>5) - (usec>>9);
@@ -525,13 +526,23 @@ void
UTI_Int64ToTimeval(NTP_int64 *src,
struct timeval *dest)
{
uint32_t ntp_sec, ntp_frac;
/* As yet, there is no need to check for zero - all processing that
has to detect that case is in the NTP layer */
dest->tv_sec = ntohl(src->hi) - JAN_1970;
ntp_sec = ntohl(src->hi);
ntp_frac = ntohl(src->lo);
#ifdef HAVE_LONG_TIME_T
dest->tv_sec = ntp_sec - (uint32_t)(NTP_ERA_SPLIT + JAN_1970) +
(time_t)NTP_ERA_SPLIT;
#else
dest->tv_sec = ntp_sec - JAN_1970;
#endif
/* Until I invent a slick way to do this, just do it the obvious way */
dest->tv_usec = (int)(0.5 + (double)(ntohl(src->lo)) / 4294.967296);
dest->tv_usec = (int)(0.5 + (double)(ntp_frac) / 4294.967296);
}
/* ================================================== */