[ibis-macro] Re: What happens when Init_Returns_Impulse = False?
- From: "Todd Westerhoff" <twesterh@xxxxxxxxxx>
- To: <ibis-macro@xxxxxxxxxxxxx>
- Date: Fri, 23 Apr 2010 16:13:23 -0400 (EDT)
Arpad,
Sorry for the delay in reply.
Given: Use_Init_Output only applies to Time Domain simulation,
Then:
Init_Returns_Impulse = False, Use_Init_Output = False, Getwave_Exists =
True
and
Init_Returns_Impulse = True, Use_Init_Output = False, Getwave_Exists =
True
are functionally equivalent from a Time Domain simulation point of view.
Extra credit: the two cases are not the same from a Statistical simulation
point of view. The eye produced by the first case will not include the
model's equalization, while the eye produced by the second case will.
Therefore, models that conform to:
Init_Returns_Impulse = True, Use_Init_Output =
False, Getwave_Exists = True
Fully support both Statistical and Time Domain simulation. Is that the
answer to the question you were asking?
Todd.
________________________
Todd Westerhoff
VP, Software Products
SiSoft
6 Clock Tower Place, Suite 250
Maynard, MA 01754
(978) 461-0449 x24
twesterh@xxxxxxxxxx
www.sisoft.com
_____
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
Sent: Thursday, April 22, 2010 7:31 PM
To: IBIS-ATM
Subject: [ibis-macro] Re: What happens when Init_Returns_Impulse = False?
Todd,
In that case, how is Init_Returns_Impulse = False
different from Use_Init_Output = False?
I admit, I may have to brainwash myself now with
the recent revelations about section 2.3, but I
would appreciate your (or any one else's) insight
on this one...
Thanks,
Arpad
===================================================
_____
From: Todd Westerhoff [mailto:twesterh@xxxxxxxxxx]
Sent: Thursday, April 22, 2010 12:13 PM
To: Muranyi, Arpad; 'IBIS-ATM'
Subject: RE: [ibis-macro] What happens when Init_Returns_Impulse = False?
All,
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.
________________________
Todd Westerhoff
VP, Software Products
SiSoft
6 Clock Tower Place, Suite 250
Maynard, MA 01754
(978) 461-0449 x24
twesterh@xxxxxxxxxx
www.sisoft.com
_____
From: ibis-macro-bounce@xxxxxxxxxxxxx
[mailto:ibis-macro-bounce@xxxxxxxxxxxxx] On Behalf Of Muranyi, Arpad
Sent: Thursday, April 22, 2010 12:00 PM
To: IBIS-ATM
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.
Options:
- 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.
Thanks,
Arpad
======================================================
Other related posts:
