akashaye:
You are right . ami model has to be sophisticated and must have

1. internal buffering
    yes you may have to collect data form multiple getwave before the model can do anything useful

2. in a realistic case you do not expect the wave_size to change between calls. But you are right, as it stands today the model is not guaranteed constant size form call to call.

also as you have already figured,  resampling is very crucial. Buffering and resampling merits careful attention from the ami model developer. Proper implementation of these two features is a must for robust eda-ami_model interaction.

I am of the view the sampling is internal to the model and EDA tool should not be doing something special thing for each model. Such an activity will only a promote a false sense of simplicity  and will end up reducing the robustness of both the eda tool and the model

 

Akshaye Sama <akshaye.sama@xxxxxx> wrote:

AMI experts,

As the wave_size is an input to the AMI_Getwave, I think the model should be capable of accepting any number for this parameter. Hence, it should also be capable of
1) collecting data from multiple calls if the data from one call is not sufficient for it to process - buffering. (no minimum specified, so theoretical cases of wave_size = 1 are also possible!)
2) dealing with this parameter varying with each call to the AMI_Getwave in a simulation. So, not assuming that the wave_size remains constant over the simulation.

A very related thing is that sample_interval is also an input to the AMI model (AMI_Init). Hence, any model must also be capable of interpolation, if it internally works on a constant sample_interval. Both for increasing or reducing the sample_interval for internal use. Practically, i can see that many Serdes RX models would be operating on a constant sample_interval internally.

Both the above complexities (buffering and possibly interpolation) will be in the AMI model (possibly, EACH AMI model). I'm thinking about additional model verification complexity because of the above two variables. To have these functions in the execution environment/EDA tool would be another possibility. Was it considered?

Thanks,
Akshaye

Muranyi, Arpad wrote:

Todd and Kumar,

 

Thanks for your messages.  My conclusion from your words

is that the intent was certainly to support multiple calls

to GetWave.  In fact, the whole purpose of architecting

Init, GetWave and Close the way it is seemed to have

happened to allow multiple calls to GetWave and then do

the Close when it is all over.

 

However, I can't seem to find much on this in BIRD104.1

and this bothers me.  Please tell me if I am missing

something, but if this is not explained in the BIRD,

consequently in the IBIS specification, we will get

all kinds of models in which people will forget to

write the additional code to make the multiple calls

work properly.

 

So I would suggest that if we all agree that this should

be a required feature for each AMI model, we should write

some text to spell it out (if this is indeed missing).

 

The above sentence made me think once again.  Does it

really have to be required?  After all, there is a

parameter called wave_size in the arguments.  But wave_size

and the total length of the waveform may not be the same.

So who decides what the wave_size is, the EDA tool, or

the model?  Seems like the EDA tool when it calls the

GetWave function.  If it was the model, then the model

could tell the EDA tool how to deal with multiple calls.

Should we do something along these lines?

 

On the other hand, if the capability of doing multiple

calls to GetWave is required, I would also request that

the Cadence Rx model should be updated with that feature

included.  We should set a good example in models which

are used to teach the newcomers to this not so easy

modeling task...

 

Thanks,

 

Arpad

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Akshaye Sama

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