DB access from C++: Skill functions required in pcells not found

Hi all,

I'm using the itkDB interface to access my layout information from C++.
Everything works fine except when I come across a PCell that uses
external skill functions.
For example the PMOS from UMC requires pcExprToString. I get the
folllowing error:

*WARNING* Pcell evaluation for UMC_18_CMOS/P_18_MM/layout has the
following error(s):
*WARNING* ("eval" 0 t nil ("*Error* eval: undefined function"
pcExprToString))
*WARNING* Error kept in "errorDesc" property of the label
"pcellEvalFailed" on layer/purpose "marker/error" in the submaster.

and the cellview of the instance is empty. I can open the layout without
any problems from icfb, so I assume that this is because I haven't
loaded the skill library that contains the function definition.

How do I make pcExprToString available to my program?

Michael

 

On Thu, 23 Jun 2005 16:42:04 +0200, Michael Ritzert wrote:
This sounds interesting!
How can you access to a cadence cdb at all using c++ ?
Where can I start on that ?

 

Michael,

First make sure that your itkDB code calls:

ilInitClients(&argc, argv, NULL, 0);

after the call to dbInit().

Any additional code that a pcell needs should get loaded via a library
libInit.il.

I think though if you use ilInitClients, the pcExprToString should get
auto-loaded from the context file it's in.

Regards,

Andrew.

 

Thank you. That did it.
You might consider adding this hint to the itkDB reference guide. How
can anybody do without pcells...?

(It seems ilInit is called automatically?)

Michael

 

Search the comp.cad.cadence archives for this 1994 jewel below.
I made some notes (e.g., CMAN is no longer an option) but this decade
old information still stands for most of what Ian wrote below.

From: (Ian Dobinson)
Subject: Re: Interfacing C with SKILL
Organization: Cadence Spectrum Services
Date: Tue, 15 Nov 1994 16:14:57 GMT

There are a number of things you can do, depending on the level of
integration you require & the amount of data that needs to be passed
back & forth.

1) SKILL 'system' or 'csh'
2) IPC
3) CMAN
4) ITK-DB

1) You could fire off a 'system' or 'csh' call from SKILL to call C
programs:

This is the simplest level. The idea is to have a SKILL program
write
out a data file which is used by your program, then have your
program
read that & write an output program which the SKILL program reads
when the system command has finished executing.

The disadvantage is that it is reasonably slow to start a system
command;
& that the CIW is blocked while waiting for the system command to
finish.

2) You could use IPC to run your program:

This is the SKILL inter-process communications level. This will
allow a C
& SKILL program to communicate through shared pipes. So, your SKILL
process writes out strings which the C program reads & vice versa.

The advantage is that you have better control of the C process from
SKILL.
You can also run this in a background (asynchronous) mode with data
handlers. Disadvantage is that the time required to pass data is
slow,
& you can of course only pass strings back & forth.

3) Use CMAN:
NOTE: CMAN is no longer documented nor supported by Cadence!

The Cadence Communications Manager. This is a message-based system
for
passing data between programs. I don't know a massive amount about
this
(haven't had a chance to use it much yet) but it is apparently
faster than
IPC, & you can pass more complex structures, but it requires more
customization on both the C & SKILL sides.

4) Use ITK:
The Cadence Integrators Toolkit. You would need to speak to your
Cadence
AE and/or salesman about this. I am not certain of the current
status of
this tool. Basically, what it allows (allowed?) was for you to write
your
own C procedures & have them compiled in to the Cadence executables
(icfb, cds3, opus0 etc.) The idea is that you also have a SKILL
wrapper,
so that your C procedure becomes callable from the SKILL level, &
since
it is a compiled in procedure it runs just as any C procedure would.

The disadvantage is that you need to pay for ITK, & it requires a
GREAT
DEAL of effort on your part to learn the system. You also have to
then
distribute the new executables to all your users, & maintain
releases of
what you have done, including re-integration to furture Cadence
releases.

Hope this information helps.
Cheers,
Ian Dobinson,

 

Jim,

Some comments on this:

In fact it's no longer available (and hasn't been for quite a few releases).

Unfortunately Ian wasn't quite correct (I'll forgive him since it was 11 years
ago). ITK doesn't allow you to link with DFII executables. It allows you to
create a standalone executable which accesses the database from C (or C++),
but you'd have to invoke that executable via IPC if you want to start it from
DFII.

You can't write a SKILL wrapper (in C) and have it linked with DFII. I don't
recall this ever being possible (perhaps it was 11 years ago - I've only been
with Cadence 10 years...)

Regards,

Andrew.