Virtually every system designed today is an amalgam of hardware and software. Unfortunately, software and circuits that communicate across the hardware/software boundary are tedious and error-prone to create. This suggests a more automatic way to synthesize them. This paper presents the SHIM language, which combines imperative C-like semantics for software and RTL-like semantics for hardware to allow a unified description of hardware/ software systems. Hardware processes and software functions

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... ommunicate through shared variables, hardware for which is automatically synthesized by the SHIM compiler, which generates C and synthesizable VHDL. I demonstrate the effectiveness of the language by reimplementing an I2C bus controller. The SHIM source is half the size of an equivalent manual implementation, slightly faster, and has a smaller memory footprint. Partial and complete hardware implementations in SHIM are also presented, showing that SHIM is succinct and effective.