Rainbow: Development, simulation and analysis tools for asynchronous micropipeline hardware design

Recently, there has been considerable interest in asynchronous design techniques, particularly at the chip level. New compositional approaches, such as Sutherland's micropipeline design philosophy, have greatly assisted development. However, sophisticated CAD systems for such specialized asynchronous systems are not yet widely available, hampering the development of asynchronous design. The Rainbow asynchronous design framework is based upon a high-level multi-view design representation for micropipelines. The system contains a collection of formally based design representation and support tools. The Green sub-language supports textual/schematic static dataflow descriptions. Yellow is an imperative, control-flow parallel language, with an Ada-like rendezvous. Tables allow concise definition of combined functional and dataflow control blocks. The sub-languages have common sets of data expressions, functions and types. The formal semantics for the Rainbow sub-languages is defined via a specialized process term language called APA, producing a compact, direct semantic representation with little unnecessary encoding. APA has micropipeline primitives, uses rich structured actions and an extended Ada-like rendezvous as its atomic communication. These features enable the semantics to be defined at a suitable high level of abstraction, i.e. micropipelines. The semantic representation acts as a basis for formal analysis tools, with the aim of extending their tractability. The Rainbow design system contains textual and graphical editors for design entry, and compilation and simulation tools, supporting animation of schematics. State generation tools provide an interface to external formal analysis systems. Rainbow currently incorporates a novel on-the-fly CTL* model checker. The MARBLE asynchronous bus design from the AMULET3 microprocessor is used as an example.