Re: [myhdl-list] Introduction and Question

[Christopher F. <chr...@gm...>]

On 12/18/12 1:09 AM, Daryl Wasden wrote:
> Christopher Felton <chris.felton <at> gmail.com> writes:
>
>>
> snip
>>
>> It might be worth investigating if GHDL has updated the VPI/VHPI
>> interface in the latest version of GHDL.  I monitor the GHDL
>> mailing-list briefly and have not seen any updates.  I think the GHDL
>> developers have mainly focused on a move to mcode.  If the status of the
>> VPI/VHPI has not changed it will be some work to implement cosimulation
>> with GHDL.  It will require the missing VPI functions implemented in GHDL.
>>
> snip
>>
>> I created this page and it was intended to be a working page towards
>> GHDL co-simulation support.  The page lists which VPI functions are
>> supported in GHDL (as of 03-Feb-2010).  The VPI function list was not
>> complete enough to attempt a VPI port for GHDL.  I do not know if things
>> have changed.
>>
>
> Okay, I investigated this. I searched the current development repository for
> the VPI functions that you had listed as Unknown in the table. It seems that
> the following have at least some implementation (at least with the bleeding
> edge repository version of GHDL).
>
> vpi_get_time()
> vpi_put_value() [ has a comment FIXME, so maybe not working too well ]
>
> These were found in the file at the following URL:
> http://svn.gna.org/svn/ghdl/trunk/translate/grt/grt-vpi.adb
>
> However, vpi_free_object() and vpi_register_systf() are declared as dummy
> functions (I'm assuming this means that they are not implemented), and I
> could not find vpi_control() anywhere. I'm not an expert ADA programmer
> so I can't be certain that they are functioning 100% according to specs, but
> they have something there. I probably don't want to worry about
> implementing the missing functionality in ADA myself, so I'll have to take
> the route you suggested below.
>
>>
>> GHDL is not available for cosimulation.  But it is supported simulator.
>> The flow for using GHDL is to convert the testbenches and run a full
>> VHDL simulation that can be coordinated from Python.  See the following
>> for some more information.
>>
>> http://www.myhdl.org/doc/current/whatsnew/0.6.html#conversion-of-test-benches
>>
>> Regards,
>> Chris
>>
>
> Thanks for pointing this out to me. Sorry I missed it. I'll look through
> it and see what I can do. If need be, I can always just write VHDL test
> benches for later simulations, just thinking it might be nice to use python...
>
> Thanks,
> Daryl
>

There doesn't seem to be a free/open source VHDL simulator that fully 
supports VPI/VHPI.  But you might be able to get one of the commercial 
simulators working with VHDL cosimulation.  Because you are at a 
University, I don't think you will have issues getting a license/student 
version for free.  Aldec's Active-HDL appears to have the most complete 
implementation of VHPI.  Mentors Modelsim has their own FLI (foreign 
language interface) for VHDL cosimulation (not VHPI).

You might want to look into one of these.  At one point I started 
exploring Modelsim's interface (FLI not available with the Altera's free 
version, IIRC).  I did not have the time to follow through and make any 
significant progress.

We might want to poll the MyHDL community and see what the most popular 
VHDL simulator used is.  Might be easier to get more help :)

Here are a couple links to possibly get started.

Modelsims FLI for VHDL:
http://www.pldworld.com/_hdl/2/_ref/se_html/manual_html/c_vhdl32.html
http://homepages.cae.wisc.edu/~ece554/new_website/ToolDoc/Modelsim_docs
/docs/pdf/fli.pdf
https://ece.uwaterloo.ca/~ece327/protected/modelsim/htmldocs/modelsim_se_fli/a_fli_intro11.html
http://www.asic-world.com/specman/interface_simulator1.html

Active-HDL VHPI:
http://www.aldec.com/resources/manuals/Active-HDL/avh00452.htm
http://www.aldec.com/resources/manuals/Active-HDL/avh00302.htm
http://www.aldec.com/en/support/resources/documentation/articles/1456
http://www.aldec.com/en/support/resources/documentation/articles/1457
http://www.aldec.com/en/search?search_field=VHPI&search_button=



Regards,
Chris