[Ns-bugs] [Bug 695] DcfManager::UpdateBackoff () uses slow HighPrecision::Div()

[code@nsnam.ece.gatech.edu]

http://www.nsnam.org/bugzilla/show_bug.cgi?id=695





--- Comment #12 from Andrey Mazo <mazo at iitp.ru>  2009-11-24 08:51:11 EDT ---
(In reply to comment #10)
> can you review it for correctness and push if it is ok ? (all tests appear to
> pass, but, who knows...)
I've noticed, that your patch and original code will behave differently in
several situations, because you've replaced lrint() with integer devision,
which works more like floor().

Old code:
Simulator::Now() = 27000;
backoffStart = 10000;
m_slotTime = 9000;
nSlots = (Simulator::Now () - backoffStart) / m_slotTime = 1.88888;
nIntSlots = lrint (nSlots.GetDouble ()) = 2;

New code:
Simulator::Now().GetMicroSeconds() = 27;
backoffStart.GetMicroSeconds() = 10;
m_slotTimeUs = 9;
nus = 27 - 10 = 17;
nIntSlots = nus / m_slotTimeUs = 17/9 = 1;

I don't know, which of the answers is correct according to the standard.

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