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Understanding list returned by geGetHierMemInst

PatrikOsgnach

Hello,

I am working on a task which involves keeping track of the history of descents into a hierarchy, but now I am a bit puzzled by the behaviour of geGetHierMemInst.

As an example, let's begin at the top cell. As expected, if I call geGetHierMemInst((getCurrentWindow)) I get nil.

The top cell has an instance named "A". If I descend into it and call (getCurrentWindow)~>cellView~>instances~>name I get all the names of instances contained in the cellView of instance "A", which is what I expect. Also, (caar geGetHierMemInst((getCurrentWindow)))~>name returns "A", as expected.

Now, what I find odd is that, if I call (caar geGetHierMemInst((getCurrentWindow)))~>cellView~>instances~>name I get a result that, not only is different from what (getCurrentWindow)~>cellView~>instances~>name returns, but it is equal to the names of all instances contained in the top cell.

What am I missing?

To be more clear about what I need to do, let's assume that I am at level 3 of this hierarchy A->"B"->"C" (A is a top cell and "B" and "C" are instance names down the hierarchy). If I select a wire in instance "C" that is connected to a pin, I want to know how this pin is connected at the level of instance "B". To do this at level "C", I use geGetHierMemInst to get to "B" and I look at all instances contained in "B" until I find an instance named "C". The I explore how wires are connected to the symbol of "C" contained in the cell view of instance "B"

Thank you.

Patrik

  • Andrew Beckett

    Hi Patrik,

    This is not surprising. If you call getCurrentWindow()~>cellView, this is the same as what geGetWindowCellView() returns - i.e. the cellView id of what is in the current window (not the top cellView, that would be geGetTopLevelCellView()) - these functions all take an optional window id, BTW.

    If you call caar(geGetHierMemInst(hiGetCurrentWindow())) then this is going to return the instance id of the instance you've descended into. If you then retrieve the ~>cellView attribute, it will get the cellView in which that instance is placed - not the cellView of the view you've switched into. Since the instance is placed in the top level, caar(geGetHierMemInst(hiGetCurrentWindow()))~>cellView will return the top level cellView Id. You could use the ~>master instead but this would tell you the cellView ID of the symbol (if it's a schematic hierarchy). You'd have to use some kind of view-switching approach to find the master cellView, or easier would just be to use the ~>cellView attribute of the next instance in the hierarchical chain (or if at the leaf, use geGetWindowCellView() or geGetEditCellView()). That way you don't have to worry about view switching (and it would work if you had a config or had switched down via some non-default route).

    Put another way - looking at a particular entry in the list returned will tell you about the instance. To find out the view you've switched into after that you need to look at the ~>cellView attribute of the subsequent instance in the list to see what that's contained within. If there are no further instances in the hierarchical chain, then it's the current cellView you want.

    Hope that's clear (ish!)

    Regards,

    Andrew

  • PatrikOsgnach

    Hello Andrew,

    Thank you for the explanation. As of now, I'm getting the cell view I need by using dbOpenCellViewByType(current_instance~>libName current_instance~>cellName "schematic"). This seems to be working fine. The approach followed by geGetHierMemInst() is bit counter-intuitive

  • Andrew Beckett

    The only downside of that is the assumption that the view is called schematic. You might have had a view called something else (e.g. "schematicNew" or "schematicFixed" - who knows what it was called?) that you switched into.

    geGetHierMemInst() is returning what it's supposed to return - the list of instance ids by which you got to here. Unfortunately there's not an API to tell you the set of cellViews that you switched into - hence the slightly convoluted approach I suggested to derive this info from what geGetHierMemInst returns.

    Regards,

    Andrew.

  • PatrikOsgnach

    Mmm... yes, it is not an assumption I can make. So, let's see if I got you:

    geGetHierMemInst() gives me this list '(A B C)

    I want to know the list of instances contained in the schematic of B. Therefore, I should do something like C~>cellView~>instances

    If I want to do the same to instance C (the last of the list and the instance I now descended into), I should do geGetWindowCellView()~>instances

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