ESP: A language for programmable devices

This paper presents the design and implementation of Event-driven State-machines Programming (ESP) - a language for programmable devices. In traditional languages, like C, using event-driven state-machines forces a tradeoff that requires giving up ease of development and reliability to achieve high performance ESP is designed to provide all of these three properties simultaneously. ESP provides a comprehensive set of features to support development of compact and modular programs. The ESP compiler compiles the programs into two targets - a C file that can be used to generate efficient firmware for the device; and a specification that can be used by a verifier like SPIN to extensively test the firmware. As a case study, we implemented VMMC firmware that runs on Myrinet network interface cards using ESP. We found that ESP simplifies the task of programming with event-driven state machines. It required an order of magnitude fewer lines of code than the previous implimentation. We also found that model-checking verifiers like SPIN can be used to effectively debug the firmware. Finally, our measurements indicate that the performance overhead of using ESP is relatively small.