RE: Analog function question

Shalom,

> Re the statement that “you cannot set a parameter value (of a 
> function) from the outside”, 
> I think there are 2 ways that you CAN do it:
> 
> 1. defparam

You're right, but I think defparam has fallen in disfavor with
at least the SV community and it is not widely supported by
simulators.

> 2. Use a parameter which is defined in the module enclosing the 
> function. That parameter value CAN be overridden.

But then it is not longer the same parameter anymore, it is just
a local parameter which happens to share the same name. Per 4.6.1
it can only reference local variables or variables passed in as
arguments; the whole paragraph does not mention parameters
anywhere.

Or, is this what you mean:

module test_me (a, b);
parameter integer n = 2 from [0:inf);
inout[0:n-1] a, b;
electrical[0:n-1] a, b;

  analog function integer some_array_manip;
  parameter integer n = n;
  inout[0:n-1] a;

  ...

  endfunction

  ...

endmodule

The reference to parameters of the enclosing module is not mentioned
in 4.6 explicitly, but the above looks acceptable to me.

I stand corrected :-)

Regards,
Marq


> 
> Shalom
> 
> 
> 
> From: owner-verilog-ams@eda.org [mailto:owner-verilog-ams@eda.org] 
> On Behalf Of Marq Kole
> Sent: Friday, September 16, 2005 10:28 AM
> To: verilog-ams
> Subject: Re: Analog function question
> 
> 
> Oops, need to correct a small mistake below: 
> 
> > Sri, Arpad, 
> > 
> > > In strict accordance to the BNF it cant be done yet. I think it was 
> > > an oversight/bug in the BNF and the intent was to put it in there.
> > 
> > In accordance with the BNF, the input declaration is mentioned as a 
> > digital_input_declaration in Annex A, so its actual definition is in 
the 
> > IEEE 1394-1995 standard. See Mantis item #870. 
> > 
> > For array arguments see Mantis item #869 describing the problem - it 
is 
> > rather an issue of documentation (explanation + example) than a 
missing 
> > item in the standard. 
> > 
> > > 
> > > regards,
> > > Sri
> > > 
> > > Muranyi, Arpad wrote: 
> > > Sri,
> > > 
> > > I just saw your 2nd reply, but since I had this almost finished,
> > > I will send it out anyway...  So according to your 2nd message,
> > > this can't be done (yet)?
> > > ----------------------------
> > > Thanks for the quick answer.  Sorry, but I am still not sure
> > > about it.  The sections you quoted from the LRM seem to allow
> > > the array inside the function as a block item, but I still
> > > don't see how I can pass an array into the function (and
> > > pass it as a real variable array, not as a parameter array).
> > 
> > Parameter arrays in functions wouldn't help you anyway, as you 
> > cannot set them from outside the function, and once initialized, 
> > you cannot alter them from inside the function either. 
> > 
> > > Would you be so kind and help me with an example?  If the
> > > input "in1" is an array, how would you declare it in the
> > > function?
> > > 
> > > analog function real myFunctionName;
> > > input in1;
> > > real  in1[1:5];    <--------- How would I know the size?
> > 
> > You'd know the size as the above analog function declaration tells 
> > you the size. There is at this moment no way to make an array argument 

> > with parameter-controlled size in an analog function in Verilog-AMS -- 

> 
> I mean an argument-controlled size given the fact that you cannot set 
> a parameter value from the outside. So a call: 
> 
>   myArrayFunction(myArraySize, myArray); 
> 
> Where myArraySize argument carries the length of the myArray argument 
> cannot be handled in current Verilog-AMS. 
> 
> > we need to check what System-Verilog does to resolve that for a future 

> > LRM, I think. 
> > 
> > > begin
> > > ...
> > > ...
> > > end
> > > endfunction
> > > 
> > > 
> > > Thanks,
> > > 
> > > Arpad
> > 
> > Marq Kole
> > Competence Leader Analog Simulation, Philips ED&T