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geomOr vs. geomCat

marcelpreda

Hi there,

We have to maintain some drc code and noticed that there is used geomCat() when logically geomOr() will make sense.
Reading the the documentation we understood that geomCat() is almost the same as geomOr(), except that teh shapes are not merged and the net/shape ids are preserved.

I guess that the previous implementer was using geomCat() instead of geomOr(), because I assume geomCat() is faster. Could be that the reason?

Any idea in which case geomCat() makes more sense than geomOr()?

Thank you,

Marcel

  • Andrew Beckett

    Marcel,

    There's occasionally a need to do some kind of check on the raw shapes rather than merged shapes, although this is fairly rare. For example, many years ago I worked for a company that had their own mask-making tools and these (for some bizarre reason) didn't merge the shapes first - and there was an undersize bias on the drawn shapes on certain metal layers. This meant that if you had two metal shapes on the same layer it wasn't sufficient to abut them, you had to overlap them by enough because otherwise when the shrink occurred you ended up with a small space between them - so I needed to check in this in Diva. Rather unusual though - but I have on occasion since other needs for looking at the raw data. If I remember rightly (I'm not quite online at the moment) the Diva drc command has a "raw" keyword which enables this - obviously though it's no good if you've had to combine some layers together before and they've all been or'd already - hence geomCat being useful.

    Yes, it's probably faster, but the result will probably get merged at some point anyway so it may not really save you anything.

    Andrew

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