Re: gEDA-user: discussion on what busses *mean*

[DJ Delorie <dj@xxxxxxxxxxx>]

Right, when we have a signal-pin-symbol relation, we have a bunch of
information:

* net name
* pin number
* pin sequence
* pin label
* physical pin location

If I have a bus A[1:3] connected to pin EN[0:2] at pin number 4,8,7 -
I mean the same as if I had connected net A1 to pin EN0 at 4, A2 to
EN1 at 8, and A3 to EN2 at 7.

If in PCB I decide I need to swap EN0 and EN2 to get the routing the
way I want, I need to do a pin swap.  Normally we'd just change the
pin numbers on the symbol (slotting, pin mapping) or reconnect the
nets in gschem.  But "reconnect the nets" is difficult if they're not
independent (i.e. they're a bus) so you have to do it with pin
numbers, but a "bus pin" doesn't have *a* number, it has a *list* of
numbers, so you have to swap within the list.

Or between a number in one list, and another number elsewhere, if the
swap map allows it.


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