2005 Articles

SHIM: A Deterministic Model for Heterogeneous Embedded Systems

Edwards, Stephen A.; Tardieu, Olivier

Typical embedded hardware/software systems are implemented using a combination of C and an HDL such as Verilog. While each is well-behaved in isolation, combining the two gives a nondeterministic model whose ultimate behavior must be validated through expensive (cycle-accurate) simulation. We propose an alternative for describing such systems. Our SHIM (software/hardware integration medium) model, effectively Kahn networks with rendezvous communication, provides deterministic concurrency. We present the Tiny-SHIM language for such systems and its semantics, demonstrate how to implement it in hardware and software, and discuss how it can be used to model a real-world system. By providing a powerful, deterministic formalism for expressing systems, designing systems and verifying their correctness will become easier.