@ Unict

During 2008 a couple of students of the University of Catania in collaboration with Simply RISC developed an AMBA Bridge for the S1 Core as their graduation thesis.

Their original intent was to take part in the OpenSPARC Community Innovation Awards Contest but they did not meet the deadline for the submission of their work to the contest - just for a few days.

They were very disappointed on September 21 when they heard that a very similar project (developed by Gaisler Research) was awarded two prizes for a total of 75K USD.

We have put to Salvatore Cammisuli (on the left) and Nunzio Di Paola (on the right) just a couple of questions:

Simply RISC: Salvatore, have you seen the AMBA bridge developed by Gaisler Research? According to you, what is the main difference with the bridge designed by Nunzio and you?

Salvatore Cammisuli: The two bridges share a similar background; both are based upon the infrastructure provided by the environment of the Simply RISC S1 Core that simplifies very much the build of one of the SPARC Cores of the OpenSPARC T1.

But the very first obvious thing that a developer would notice is that Gaisler has developed the bridge in VHDL while ours is written in Verilog. And being all the rest of the OpenSPARC code written in Verilog this means that we can easily simulate our design with free tools such as Icarus Verilog, while a mixed-language simulation is much more difficult and requires at least some commercial tool.

SR: Nunzio, there is something else that you want to add about your bridge?

Nunzio Di Paola: For the work that we have done for our graduation thesis we had to ensure that our bridge was 100% compliant with the AMBA 3 AHB-Lite specification. To accomplish this task we had to adapt the official AXI protocol checker into the design and we considered completed our work only when we were able to eliminate the 100% of the warning messages printed by the checker.

If we had not used the protocol checker probably now we had a bridge that was only 99% compliant... and perhaps we had 75K USD more!

SR: Salvatore, are you going to release your work anyway for free?

SC: Of course. We are providing under the GPL2 license all the code that we have developed. We just had to remove the source of the AXI protocol checker, that is copyrighted by ARM, and several files of the Open Verification Library required by the checker and copyrighted by Accellera.

SR: Nunzio, what next?...

NDP: Now that we hold a M.Sc. in Computer Engineering summa cum laude we hope to find a job for us in Sicily: we don't want to emigrate.

But we can't stop thinking about the contest... the philosopher Friedrich Nietzsche used to say that That which does not kill us makes us stronger...

Footnote: The AMBA Bridge for the S1 Core is now available for download from the Simply RISC website.