[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: gEDA-dev: Newbie developer guidelines.
On Tuesday 24 April 2007 15:07, Sven Wilhelmsson wrote:
> On Tue, 2007-04-24 at 14:35 -0400, Stuart Brorson wrote:
> > 2. Alternately, just choose a project you think you'd like
> > (for example implementing JFET models), make it work, and
> > then send Al the patches.
>
> Note that gnucap-2007-02-21 and later can run models from
> ngspice as plugins. I have tried the JFET model and it seems
> to work. Therefore the priority is lowered for the JFET model
> IMHO. (Maybe there are still reasons for doing it. ??? )
Two reasons I can think of ....
Licensing .. There is a need for a GPL jfet model that can be
distributed by default with the core. The Spice model is
licensed under one of the many variants of the old Berkeley
license which is not GPL compatible. With plug-ins, the
license incompatibility only means that the models must not be
in the same tarball as the simulator core, and you can't
legally distribute a static linked executable with code from
mixed licenses.
Performance ... The performance of native models is better than
Spice models with the wrapper. There is overhead in the
wrapper.
Reasons not to do it ...
The way to do it that is consistent with old stuff is a ".model"
file. This format is being phased out in favor of Verilog-A,
but the tools are not ready.
Users want standard models. When you make a new implementation
there will be subtle differences, making it deviate slightly
from what users think is the standard. This is why gnucap is
moving to being able to use unmodified models from others,
rather than having its own.
There are 3 (at least) jfet models now .. one is in the
spice3f5 models tarball, two are in the ngspice models tarball.
The one in the spice3f5 models tarball is probably preferred
because it is most standard. There is another one in older
versions of spice that I have not packaged yet. This will
probably be the "spice3c-models" tarball .. for those who need
the exact bugs of the old models.
_______________________________________________
geda-dev mailing list
geda-dev@moria.seul.org
http://www.seul.org/cgi-bin/mailman/listinfo/geda-dev