[ibis-macro] Re: What happens when Init_Returns_Impulse = False?

  • From: "Todd Westerhoff" <twesterh@xxxxxxxxxx>
  • To: <Arpad_Muranyi@xxxxxxxxxx>, "'IBIS-ATM'" <ibis-macro@xxxxxxxxxxxxx>
  • Date: Thu, 22 Apr 2010 13:12:45 -0400 (EDT)



As I understand it, Init is expected to modify the impulse response in
place in memory.  The simulator passes the model a pointer to the impulse
response, and uses that same pointer to access the result when the Init
call returns control to the simulator.


If the model doesn't touch the impulse response at all, it's there in
memory just as the simulator supplied it.





Todd Westerhoff
VP, Software Products
6 Clock Tower Place, Suite 250
Maynard, MA 01754
(978) 461-0449 x24


From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
Sent: Thursday, April 22, 2010 12:00 PM
Subject: [ibis-macro] What happens when Init_Returns_Impulse = False?


I would like to get some ideas from the authors

of the AMI specification on what the intent was

when Init_Returns_Impulse = False.


I would also like to get some suggestions on what

the Init function should return when

Init_Returns_Impulse = False.




- return the same thing that was sent into Init

- return impulse response of the filter

- return uninitialized memory (garbage or noise)


It seems that either the first or second answer

may be the correct one if I consider that the

calculations are supposed to be done "in place",

i.e. in the same memory space where the input

was placed.  If nothing is done, the memory will

still contain the input data in that place.  If

something is done, like returning the filter only

impulse response, we will get that in that memory

space.  It is hard to turn that memory space into

uninitialized memory, unless we use a random number

generator to do something that can mimic that effect.







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