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[PATCH] NTP shift_right cleanup

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Create a macro shift_right() that avoids the numerous ugly conditionals in the
NTP code that look like:

        if(a < 0)
                b = -(-a >> shift);
        else
                b = a >> shift;

Replacing it with:

        b = shift_right(a, shift);

This should have zero effect on the logic, however it should probably have
a bit of testing just to be sure.

Also replace open-coded min/max with the macros.

Signed-off-by : John Stultz <johnstul@us.ibm.com>

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
john stultz
2005-10-30 15:01:42 -08:00
committed by Linus Torvalds
parent 9c0cbd54ce
commit 1bb34a4127
3 changed files with 24 additions and 61 deletions
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25
kernel/time.c
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@@ -338,30 +338,20 @@ int do_adjtimex(struct timex *txc)
if (mtemp >= MINSEC) {
ltemp = (time_offset / mtemp) << (SHIFT_USEC -
SHIFT_UPDATE);
if (ltemp < 0)
time_freq -= -ltemp >> SHIFT_KH;
else
time_freq += ltemp >> SHIFT_KH;
time_freq += shift_right(ltemp, SHIFT_KH);
} else /* calibration interval too short (p. 12) */
result = TIME_ERROR;
} else { /* PLL mode */
if (mtemp < MAXSEC) {
ltemp *= mtemp;
if (ltemp < 0)
time_freq -= -ltemp >> (time_constant +
time_constant +
SHIFT_KF - SHIFT_USEC);
else
time_freq += ltemp >> (time_constant +
time_freq += shift_right(ltemp,(time_constant +
time_constant +
SHIFT_KF - SHIFT_USEC);
SHIFT_KF - SHIFT_USEC));
} else /* calibration interval too long (p. 12) */
result = TIME_ERROR;
}
if (time_freq > time_tolerance)
time_freq = time_tolerance;
else if (time_freq < -time_tolerance)
time_freq = -time_tolerance;
time_freq = min(time_freq, time_tolerance);
time_freq = max(time_freq, -time_tolerance);
} /* STA_PLL || STA_PPSTIME */
} /* txc->modes & ADJ_OFFSET */
if (txc->modes & ADJ_TICK) {
@@ -384,10 +374,7 @@ leave: if ((time_status & (STA_UNSYNC|STA_CLOCKERR)) != 0
if ((txc->modes & ADJ_OFFSET_SINGLESHOT) == ADJ_OFFSET_SINGLESHOT)
txc->offset = save_adjust;
else {
if (time_offset < 0)
txc->offset = -(-time_offset >> SHIFT_UPDATE);
else
txc->offset = time_offset >> SHIFT_UPDATE;
txc->offset = shift_right(time_offset, SHIFT_UPDATE);
}
txc->freq = time_freq + pps_freq;
txc->maxerror = time_maxerror;