[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 19:43:54 +0000

Walter,

I wasn't talking about added functionality.  The reason
I got into this brain storming is to find a way to make
tap parameters Reserved parameters.  This is motivated
by the discussion of whether InOut and Out should be
allowed with Model_Specific parameters.  Your reason for
wanting that was the tap coefficient example.  Your
argument is that these can be only Model_Specific, and
these need to have the Out capability so that the model
can return its optimized tap coefficients to the EDA tool.
The idea I am proposing is an attempt to make tap parameters
Reserved and thereby being able to make them Out and InOut
without sacrificing the integrity of the specification.

If I understand it correctly, currently we are making
the tap parameters Model_Specific because the number of
taps and their names might be specific to each model which
is hard to make Reserved.

Regarding the "removed functionality", I do not intend to
do that.  This is in the brain storming stage at this
point.  However, the second example indicates that there
might be ways to come up with syntax that includes Range,
Increment, List, and the like.  I don't see a limitation
there, we would just have to define each of these
representations in the spec.

Thanks,

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

From: Walter Katz [mailto:wkatz@xxxxxxxxxx]
Sent: Monday, December 12, 2011 1:32 PM
To: Muranyi, Arpad; ibis-macro@xxxxxxxxxxxxx
Subject: RE: [ibis-macro] How to make tap coefficients Reserved Parameters with 
Table

Arpad,

What you are proposing does not give any additional functionality to what is in 
BIRD 5.0, and in fact removes functionality.

The existing structure allows List, Increment, ... for each Tap. This is 
important because taps does have constrained values. Also taps be InOut or Out. 
Although Table now support "Out", they return the full table, not just the tap 
value.

What in your proposal adds functionality to what already is in IBIS 5.0?

Walter

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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