[ibis-macro] Question about the sliding window algorithm

  • From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
  • To: "IBIS-ATM" <ibis-macro@xxxxxxxxxxxxx>
  • Date: Wed, 14 May 2008 10:03:29 -0700

Hello IBIS-AMI gurus,

I am still experimenting with the SiSoft Tx and Cadence Rx
models, I am noticing that there is a difference between
these two in the way the GetWave function can be called.

The SiSoft model implemented a special mechanism to allow
the caller of GetWave to call the function multiple times
which is a feature to keep memory usage low regardless of
how long the waveform is.  (I call this the sliding window
algorithm).

The Cadence model doesn't have the additional code to make
the sliding window possible by the caller.  The GetWave
function must process the entire waveform to get correct
results.

This raises a question.  How does the caller know whether
it can call GetWave multiple times with smaller segments
of the waveform or whether it has to call it once and only
once with the entire waveform?  I tried to find the answer
to that in BIRD104, but so far wasn't able to find anything.
(Please tell me if I missed it somewhere).

If this is not spelled out in our BIRD, it is a serious flaw,
because the EDA tool doesn't have a way to know how to call
GetWave, and if it applies the sliding window algorithm to a
model that doesn't have the extra code to allow that, the
results will be bogus (see yellow waveform below).

 <<ole0.bmp>> 

If my observation is correct we must write a BIRD to take
care of this problem.

Thanks,

Arpad
===========================================================

Windows bitmap

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