diff options
Diffstat (limited to 'networking')
| -rw-r--r-- | networking/ntpd.c | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/networking/ntpd.c b/networking/ntpd.c index ff49550e9..db04eb272 100644 --- a/networking/ntpd.c +++ b/networking/ntpd.c @@ -551,13 +551,6 @@ gettime1900d(void) return G.cur_time; } -static void -d_to_tv(struct timeval *tv, double d) -{ - tv->tv_sec = (time_t)d; - tv->tv_usec = (d - tv->tv_sec) * 1000000; -} - static NOINLINE double lfp_to_d(l_fixedpt_t lfp) { @@ -1044,8 +1037,17 @@ step_time(double offset) time_t tval; xgettimeofday(&tvc); + /* This code adds floating point value on the order of 1.0 + * to a value of ~4 billion (as of years 203x). + * With 52-bit mantissa, "only" 20 bits of offset's precision + * are used (0.01 attosecond), the rest is lost. + * Some 200 billion years later, when tvc.tv_sec would have + * 63 significant bits, the precision loss would be catastrophic, + * a more complex code would be needed. + */ dtime = tvc.tv_sec + (1.0e-6 * tvc.tv_usec) + offset; - d_to_tv(&tvn, dtime); + tvn.tv_sec = (time_t)dtime; + tvn.tv_usec = (dtime - tvn.tv_sec) * 1000000; xsettimeofday(&tvn); VERB2 { |