Issue 164 in toped: feature request: net or pin name attribute read/write support for GDS2

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Status: New
Owner: analogc...@gmx.net
Labels: Type-Enhancement Priority-High OpSys-All Component-Interfaces
Usability

New issue 164 by analogc...@gmx.net: feature request: net or pin name
attribute read/write support for GDS2
http://code.google.com/p/toped/issues/detail?id=164

background:
By generating ready-to-use GDS2 files one expects a LVS clean layout. For
this certain attributes per geometry-shape are needed. I'm not sure if this
is defined in any standard but some of the EDA companies are using this to
retain the pin name when doing successively streaming-out and/or
streaming-in GDS-data.




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Comment #1 on issue 164 by krustev....@gmail.com: feature request: net or

pin name attribute read/write support for GDS2
http://code.google.com/p/toped/issues/detail?id=164

I will need a bit more info here. Some thoughts...
- GDS is owned theese days by Cadence if I'm not wrong and compliance is a
bit of a dream. I'm not aware of a formal test file approved by the
owner/maintainer.
- Not sure I can get the latest "official" format description from them
unless I buy some of their products. It's not like a standard, to buy it
legaly for ~100 bucks from IEEE. A plenty of references on the web of
course - so anybody can pick and choose...
- The original Calma GDS format contains a plenty of fields which were
either hardly used ever or not used anymore. All the format versions after
that in the majority of the cases reduce the record types.

I can continue of course, but let's get to the point:- I'll appreciate
either a formal description of the requested attributes/properties in terms
of GDS records or (even better and I believe easier) a very short example
file.
The second point will be - some help when it comes to the validation of the
feature.

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Comment #2 on issue 164 by edo...@gmail.com: feature request: net or pin

name attribute read/write support for GDS2
http://code.google.com/p/toped/issues/detail?id=164

From my experience GDS does not store any data on shapes (like pin names,
directions, etc.). LVS is supported by saving TEXT records (not in BOUNDARY
or PATH) on some designated layers which then are recognized by
verification tool.

Also, GDSII not being "standardized" is a commonly accepted truth.

[ASIC]

There are by sure a lot of possibilities in the well know verification tools to
check the GDS file against their associated schematics. But I think the golden
way is already predetermined by the most-known/used layout editor. If you insert
a pin a rectangular area will be drawn with additional (hidden) properties.
These properties (or at least one) can be transfered to the GDS2-stream if you
want. If you do not attach the information the checker tool will not recognize
the pin name of the again streamed-in GDS2-file anymore -- LVS is not clean!.

Attaching properties to geometric shapes is of course not standardized but I
assume since this is the way done by the king of layout-editors 80% of the
design- and layout-engineers are familiar with this kind of work-flow. However,
I didn't found another way to keep the pin-information in the GDS-file when
using the standard stream-out procedure..

The way you suggested could be very possible if the fab supports this and
defines some specific rules in the checker tools. It would be great to hear
about the experience of other ASIC designers. I'm always open for new ways to
get things to work ;)

best
armin

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