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instance->master != dbOpenCellViewByType()

tweeksold

First post on the newfangled board! (I hope I'm not the only one who figured out how to get here...).

My question is simple: why are these not eq()?

    
    cellView = dbOpenCellViewByType("someLib" "someCell" "schematic")
    instance = car(cellView->instances)
    instance->objType
=> "inst"
    eq(instance->master dbOpenCellViewByType(instance->master->libName
                                                instance->master->cellName
                                                instance->master->viewName))
=> nil

--tom

  • instance->master is the master cellview for the instance.

    instance->cellView is the cellview in which the instance is placed.

    If instance is a nand placed in a cell called someCell, then instance->master->cellName will be "nand" and instance->cellView->cellName will be "someCell".

    -Derek

  • Hi Derek!

    Hey, thanks for reading, man. I get the part about instance->master vs. instance->cellView.  This is the part that confuses me:

    eq(instance->master dbOpenCellViewByType(instance->master->libName
                                         instance->master->cellName 
                                         instance->master->viewName))
=> nil

    Call me crazy, but shouldn't this return t, since they're the same cellView? 

      --tom

  • But wait--there's more!

    ; Select an instance in a layout window.
eq(css()->master dbOpenCellViewByType(css()->master->libName css()->master->cellName css()->master->viewName))
=> t

; Select an instance in a schematic window.
eq(css()->master dbOpenCellViewByType(css()->master->libName css()->master->cellName css()->master->viewName))
=> nil

    So this weirdness only happens in schematics.

      --tom

  • Sorry for my quick and inaccurate response last time. I thought you were checking equality between the cellview and the instance master.

    I think the problem is likely that you have selected a pcell. Check to see if the instance has a superMaster: css()->master->superMaster

    I tried your statement in a schematic and I got t for a non-pcell and nil  for a pcell. The reason is because pcell instances have a subMaster created at evaluation time. The dbOpenCellViewByType command will open the superMaster out of the library. When you instantiate a pcell, the parameters are evaluated and a subMaster of the pcell is created. If you create another instance with the same parameters, they will reference the same master (subMaster). However, if you change the parameter on one instance, a new subMaster will be created, althouth both subMasters will reference the same superMaster.

    -Derek

  • D'oh--I forgot about pcells!!

    ; With a schematic pcell selected...
eq(css()->master->superMaster dbOpenCellViewByType(css()->master->libName 
                                                   css()->master->cellName 
                                                   css()->master->viewName))
=> t

    Thanks Derek!!

      --tom

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