Compiling occam into Field-Programmable Gate Arrays

We describe a compiler which maps programs expressed in a subset of occam into netlist descriptions of parallel hardware. Using Field-Programmable Gate Arrays to implement such netlists, problem-specific hardware can be generated entirely by a software process. Inner loops of time-consuming programs can be implemented as hardware and the less intensively-used parts of the program can be mapped into machine code by a conventional compiler. Software investment is protected since the same program can run entirely in software, entirely in hardware, or in a mixture of both. A single program can thus result in many implementations across a potentially wide costperformance range. The compilation system has been used to generate innerloops, hardware interfaces to real-world devices, systolic arrays, and complete microprocessors. In the near future we hope to have a proven version of the compiler, enabling us automatically to generate provably correct hardware implementations, including microprocessors, from higher-level specifications.