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Speakers challenge APIs for EDA interoperability

Posted: 03 May 2004 ?? ?Print Version ?Bookmark and Share

Keywords:api? eda tool? c language?

A standard API and database implementation may not be the best approach to EDA tool interoperability, according to Synopsys speakers at the Electronic Design Processes (EDP-2004) workshop here Monday (April 26, 2004). The speakers challenged advocates of the OpenAccess coalition by proposing alternatives that don't rely on C language APIs.

But the OpenAccess Coalition, which has developed a standard API and reference database implementation, had its supporters as well. Speakers from Hewlett-Packard and LSI Logic described their adoption of OpenAccess, and Sumit das Gupta, VP of technology for the Silicon Integration Initiative (Si2), provided the latest roadmap for the OpenAccess effort.

Although the OpenAccess Coalition has backing from a number of key user companies, its database technology comes from Synopsys rival Cadence Design Systems, and Synopsys has declined to join the initiative. However, Synopsys is working with the coalition to build an API-based "bridge" between the Synopsys Milkyway and OpenAccess databases.

Dwight Hill, principal engineer at Synopsys, outlined an approach to interoperability based on the Tcl scripting language, the Synopsys Common Command Interpreter (CCI), and "collections," which provide a way to represent large groups of objects. "The primary interface for most users is scripts, so let's standardize on that," he said.

CCI was developed by the PrimeTime group inside Synopsys. Hill said that it provides "consistent, easy-to-use commands" and can provide a layer on top of Tcl. Collections are internal data structures representing ordered lists of objects. The combination would provide easy access to the different underlying tool databases, Hill said.

Hill noted that C/C++ APIs can be extremely lengthy, require memory management, and don't guarantee privacy. "All timers use SDC [Synopsys Design Constraints] as a command language," he said. "If another tool wants to access a timer, you don't need an API, just write a command."

Because Hill's plan lacks a unified database, there's no foundation underneath, das Gupta told EE Times. "It's like trying to take off without going down the runway," he said.

In a separate presentation, Noel Strader, product marketing manager for Milkyway at Synopsys, said there are three approaches to interoperability. The first is file read/write, second is extension languages such as Tcl or Skill, and the third is a compiled language API.

Of these, he said, APIs are primarily used by CAD interoperability engineers for linking proprietary or third-party tools into design systems. He estimated there are perhaps 300 of these engineers in the world, a figure immediately challenged by audience members from IBM, Hewlett-Packard, and other companies.

"Interoperability is needed at three levels, and talking about one misses the point," he said. "For most users and developers, extension languages provide the most productivity. The C API is needed for a diminishing set of applications."

But presenters from LSI Logic and Hewlett-Packard disagreed. Scott Peterson, director of RapidChip design methodology at LSI Logic and chair of the OpenAccess Coalition, detailed his company's implementation of a structured ASIC toolset based on the OpenAccess database.

Peterson also described a Milkyway-to-OpenAccess bridge based on Python, and said he was looking forward to a link that will allow in-memory transfers. He said LSI has "always been pro-API" and has requested Synopsys' Milkyway API, in addition to embracing OpenAccess.

Jim Wilmore, CAD systems architect at Hewlett-Packard, described HP's development of a 90nm design flow based on OpenAccess. What it allows, he said, is an integrated, best-in-class flow. "This is essential for nanometer design," Wilmore said. "We have reached a point where the effects in nanometer processes can't be decoupled."

Wilmore offered a vision in which "engines" from academia, industry, and in-house development all operate on one run-time database, using the OpenAccess API. These engines would, presumably, carry far less overhead than standalone tools. But the transition from tools to engines involves some difficult business issues, he acknowledged.

"In today's world, power and signal integrity require really tight cooperation," replied Synopsys' Strader. "I don't see that as being provided by engines in any way that we describe them today."

Synopsys' Hill questioned whether a consortium such as OpenAccess can really provide a solution to tough problems like power analysis for multi-Vdd, multi-mode chips. "I'm optimistic," Wilmore replied. "The working groups I've been involved in have come up with better solutions than I, or anyone in the company, has had."

What's up next for OpenAccess, said das Gupta, is the 2.2 release in September 2004, which will come with X routing support, constraint modeling, and a Milkyway-to-OpenAccess translator.

EDP-2004 presentations will be available in May at the web site.

- Richard Goering

EE Times

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