Hi,
The "low_part * mult" multiplication of the old function may overflow a
32bits integer...
This patch both fix the overflow issue (tested with frequencies up to
20Ghz), and make the result of the function lose less precision.
Please apply,
-- Yoann Vandoorselaere, http://www.prelude-ids.org"Programming is a race between programmers, who try and make more and more idiot-proof software, and universe, which produces more and more remarkable idiots. Until now, universe leads the race" -- R. Cook
--- linux-benh/kernel/cpufreq.c 2002-08-21 17:27:52.000000000 +0200 +++ linux-yoann/kernel/cpufreq.c 2002-08-22 11:27:09.000000000 +0200 @@ -78,14 +78,16 @@ static unsigned int cpufreq_ */ static unsigned long scale(unsigned long old, u_int div, u_int mult) { - unsigned long low_part, high_part; - - high_part = old / div; - low_part = (old % div) / 100; - high_part *= mult; - low_part = low_part * mult / div; - - return high_part + low_part * 100; + unsigned long val, carry = 0; + + mult /= 100; + div /= 100; + val = old / div * mult; + + carry = old % div; + carry = carry * mult / div; + + return val + carry; }
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This archive was generated by hypermail 2b29 : Fri Aug 23 2002 - 22:00:24 EST