[ntp:hackers] ntp_loopfilter.c bug?
Mark Martinec
Mark.Martinec at ijs.si
Wed Apr 6 16:19:36 PDT 2005
Tonight's snapshot contains the following code section,
which has been modified recently. It looks suspiciously like a bug,
even without trying to understand what it does:
ntp_loopfilter.c near line 280:
/*
* Update the jitter estimate.
*/
etemp = SQUARE(clock_jitter);
dtemp = max(abs(fp_offset - last_offset),
LOGTOD(sys_precision));
dtemp = SQUARE(fp_offset - last_offset);
clock_jitter = SQRT(etemp + (SQUARE(dtemp) - etemp) /
CLOCK_AVG);
dtemp is computed, result discarded, and computed again.
A value is squared twice.
Mark
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