[Magic-dev] Importing GDS from Astro into Magic?

[R. Timothy Edwards]

Dear Mark and John,

> 3.  Magic 7.5.120  seems to handle the $$ file names OK when reading in the gds.  The issue
> is once you save, quit , restart magic.  Magic doesn't seem to be able to find the files
> starting with $$.  I ran across this 10 minutes ago!  So it seems the issue how load
> passes the string to the OS.

I should probably clarify that as long as Magic is running under Tcl/Tk, the
Tcl/Tk interpreter *will* attempt to convert anything beginning with "$"
into a variable if it is typed on the command line.  Thus, once you have
created such a cell name, you will have to start referring to it with
backslash character escapes (e.g., "\$\$M2_M1").  This is, of course,
all Cadence's fault.

> MY quick fix will be to rename the cells and corresponding magic files.
> Another fix would be to flatten the wires/vias.  

Which reminds me to mention another useful option I added to the "gds"
command, which is "gds flatten on".  This will check the GDS input for
cells with a trivial amount of geometry in them (defined as less than
10 rectangles) and flatten them on input.  By the way, if you want to
*generate* these kind of contacts (which are widely used because the
array record in GDS is very compact, but only subcells can be arrayed),
use the option "gds contacts true".

And while we're on the subject of obscure GDS options in Magic, don't
miss the option "gds merge true", which compiles all the tiles of
Magic's database into polygons.  This is very helpful when transferring
data between Magic and other EDA tools, none of which tend to deal well
with the millions of fractured tiles that Magic tends to output (we had
a particular problem with exporting geometry to the field-solver HFSS).
It's a bit slow, though.  I was thinking about offering $100 to anyone
who could speed up the algorithm by a factor of 2. . .

						---Tim

+--------------------------------+-------------------------------------+
| Dr. R. Timothy Edwards (Tim)   | email: tim at opencircuitdesign.com    |
| Open Circuit Design, Inc.	 | web:   http://opencircuitdesign.com |
| 22815 Timber Creek Lane        | phone: (301) 528-9364               |
| Clarksburg, MD 20871-4001      | cell:  (240) 401-0616               |
+--------------------------------+-------------------------------------+