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Register Automation: A visit with Semifore

Gabe Moretti, Senior Editor

During the just passed DVCon U.S. I met with Richard Weber, CEO of Semifore (  When I was asked to meet with him by Jill Jacobs I thought she was introducing a new company.  I was wrong! Semifore was founded in 2006 and is an on-going healthy company that has now decided to be more open to the press.

Semifore is a small company, only seven full time employees, with the mission to develop technology that significantly reduces cost to develop and verify complete control register automation of complex ASIC, SoC, and FPGA-based design.  The company offers an advanced compiler for specification, verification, documentation, and implementation of configuration, status registers and address maps for complex designs.

Semifore is self-funded, profitable, and with a healthy list of customers that include a significant number of tier 1 companies.  It is not presently seeking third party funding, although I have pointed out that further significant expansion of the business will require a significant investment.  I put the company in the “life-style” bucket, a good group whose recent principal alumnus is Denali.

When Richard told me that Semifore had developed its own language, CSRSpec, all sorts of warning bells went off in my head.  Not another language! I was thinking.  What amount of work would be necessary to get it accepted?  It turned out that my fears were unfounded.  The language not only interfaces with industry standard busses, but also reads and writes SystemRDL, IP-XACT, and spreadsheets.  It produces RTL, firmware header files, verification data, and documentation in HTML, Word, FrameMaker, and others.  In other words, it fits seamlessly into a design flow with third party tools.

Figure 1 How CSRCompiler fits in the design flow

The limitations of IP_XACT are main reason for the new language.  Richard described it as “kicking IP_XACT up a notch (or 10)”.  Actually the description is not quite fair since IP_XACT, and IEEE 1685 its natural derivative, is a “Standard for IP-XACT, Standard Structure for Packaging, Integrating and Re-Using IP Within Tool-Flows” does not directly address total register automation.  It is more accurate to say that CSRSpec implements functions as a supplement of the capabilities of IP_XACT.  For sure CSRSpec does a much better job than SystemRDL, a de-facto standard developed by the SPIRIT consortium, whose further development has been ignored by the EDA community.  It is true that within the Accellera System Initiative, a SystemRDL Working Group was formed in 2012, but the group is still seeking members and, to my knowledge, has done no development work so far.

It is clear that niche companies can still find a way to contribute to EDA and in the process generate a respectable revenue stream.  But it takes both ingenuity and dedication.  Before founding Semifore Richard Weber and Jamsheed Agahi worked at Cisco and each have more than twenty years of design and verification experience.  Herb Winsted, VP of business development and Customer Care was a mask designer at AMD and then provided sales support at Cadence, Silicon Valley Research, and Silvar-Lisco.  Rob Callaghan, COO has more than 25 years of experience in the electronic industry, including a stint at Cadence.

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