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> Wouldn't it change in some cases? Where you have schematic with signal nets > drawn to show flow of signal through a system? And where your symbols for slot parts > do not go down to single sections? I define swapping at layout as a modification that doesn't change the geometry of the schematic, partly because it's too hard to annotate but mostly because layout isn't a schematic capture tool. So the scope of layout-based pin/gate swapping is: changes that can be reflected only by changing the pinnumber= attribute (and optionally, if we can figure out how, the refdes= one) on an existing symbol. So you can rearrange the eight data pins of a RAM chip, but not move half of them to a different chip. You can swap the two inputs of a NAND gate, or swap two NAND gates, but not swap a NAND for a NOR or use part of an N+1 input NAND gate elsewhere. > In that case, nets drawn to not overlap and "appear" simple and > streamlined might have to change to crossing over some to allow for > a decision made based on layout goals. Shouldn't have to. If you have two schematic lines going to a NAND gate, but they cross on the layout, you do a pin swap. This swaps the physical pins on the layout, but *renumbers* the pins on the schematic. I.e. if the top pin was "1" before, the top pin migh be "2" after swapping. > Strategy might not get executed all the way in real life. I don't > assume changing the pinnumber= attribute on existing symbols is all > that will ever be needed, even if it handles most cases. I'm limiting it to that anyway, because that's the case we can handle. If you need something more complicated, you do it in capture instead of layout.
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