[ibis-macro] Re: How to make tap coefficients Reserved Parameters with Table

  • From: "Muranyi, Arpad" <Arpad_Muranyi@xxxxxxxxxx>
  • To: "ibis-macro@xxxxxxxxxxxxx" <ibis-macro@xxxxxxxxxxxxx>
  • Date: Mon, 12 Dec 2011 19:51:36 +0000

Ambrish,

True, they are mostly for the models, but Walter gave us
an example for how the tool could also use the returned
values from the models.  True, Walter's example is for
simple display purposes, but I suspect that if we defined
this as Reserved parameters, the EDA tools could do more
with the returned values than just that.

The main advantage I see in making these Reserved is
that we can unambiguously define in the spec what
these parameters do and how they should be dealt with
in the model and the tool.  Also, this would hopefully
eliminate the argument that we need to support InOut
and Out parameters under Model_Specific, which is a
nightmare.

Thanks,

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

From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Ambrish Varma
Sent: Monday, December 12, 2011 1:36 PM
To: ibis-macro@xxxxxxxxxxxxx
Subject: [ibis-macro] Re: How to make tap coefficients Reserved Parameters with 
Table

Arpad,
Aren't tap coefficients more for the models and less for the EDA tools? When 
and how do you see them being used by the EDA tool? In other words - do you see 
any particular advantage for having these as Reserved Params and not Model 
Specific?

Thanks,
Ambrish.

[cid:image001.gif@01CCB8D5.0E265600]



Ambrish Varma   |  Member of Consulting Staff

P: 978.262.6431   www.cadence.com<http://www.cadence.com>










________________________________
From: ibis-macro-bounce@xxxxxxxxxxxxx<mailto:ibis-macro-bounce@xxxxxxxxxxxxx> 
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]<mailto:[mailto:ibis-macro-bounce@xxxxxxxxxxxxx]>
 On Behalf Of Muranyi, Arpad
Sent: Monday, December 12, 2011 2:24 PM
To: ibis-macro@xxxxxxxxxxxxx<mailto:ibis-macro@xxxxxxxxxxxxx>
Subject: [ibis-macro] How to make tap coefficients Reserved Parameters with 
Table

All,

I just couldn't leave this idea alone, and looked at
BIRD 132 to see how Tables could be used for taps.
Here is an example that I can imagine:

(DFE_taps (Usage InOut) (Type String Float)
  (Table
    (Labels "Tap name" "Tap value")
    ("tp-1"  -0.1)
    ("tp0"    0.8)
    ("tp1"    0.1)
 )
  (Description "Initial DFE tap coefficients.")
)

I don't see why this couldn't be under the Reserved parameters
section.  Note that it doesn't have to be a required parameter
because not all models may have a DFE.  The specification can
provide a detailed description on when/how/why this parameter
is used by the EDA tool and model, etc...

A more elaborate version of the above example is an equivalent of
the example on pg. 150 of the v5.0 spec (including Range and Default):

(DFE_taps (Usage InOut) (Type String Float Float Float Float)
  (Table
    (Labels "Tap name" "Typ value" "Min value" "Max value" "Default value")
    ("-2"   0.1  -0.1  0.2  0.1)
    ("-1"   0.2  -0.4  0.4  0.2)
    ("0"    1    -1    2    1)
    ("1"    0.2  -0.4  0.4  0.2)
    ("2"    0.1  -0.1  0.2  0.1)
 )
  (Description "DFE tap coefficients.")
)


Comments?  Questions?

Thanks,

Arpad
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