Copilot is a realtime programming language and Runtime Verification framework. It allows users to write concise programs in a simple but powerful way using a stream-based approach.

Programs can be interpreted for testing, or translated C99 code to be incorporated in a project, or as a standalone application. The C99 backend ensures us that the output is constant in memory and time, making it suitable for systems with hard realtime requirements.

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-- Raw temperature from sensor, range -50.0C to 100.0C.
temp :: Stream Word8
temp = extern "temperature" Nothing

-- Transform the temperature to Celsius.
ctemp :: Stream Float
ctemp = (unsafeCast temp) * (150.0 / 255.0) - 50.0

-- Bind two triggers with a 3.0C hysteresis.
spec = do
  trigger "heaton"  (ctemp < 18.0) [arg ctemp]
  trigger "heatoff" (ctemp > 21.0) [arg ctemp]

News

Release 3.20 – 2024-07-07

We are pleased to announce the release of Copilot 3.20, a stream-based DSL for writing and monitoring embedded C programs, with an emphasis on correctness and hard realtime requirements. Copilot is typically used as a high-level runtime verification framework, and supports temporal logic (LTL, PTLTL and MTL), clocks and voting algorithms.

Among others, Copilot is being used at the Safety Critical Avionics Systems Branch of NASA Langley Research Center for monitoring test flights of drones.

This release introduces support to upload the values of fields in structs, and add support for GHC 9.8. We also remove deprecated functions from copilot-language that had been renamed in prior versions for compatibility with newer versions of GHC.

Details are available here, and here.

Current emphasis is on introducing support to update the values of elements in arrays, improving the codebase in test coverage, removing unnecessary dependencies, hiding internal definitions, and formatting the code to meet our new coding standards. We also plan to add extensions to be able to visualize streams. Users are encouraged to participate by opening issues and asking questions via our github repo.

License

Copilot is distributed under the BSD-3-Clause license, which can be found here.

Acknowledgements

We are grateful for NASA Contract NNL08AD13T to Galois, Inc. and the National Institute of Aerospace, which partially supported this work.

Additionally NASA Langley contracts 80LARC17C0004 and NNL09AA00A supported further development of Copilot.

We would like to thank Kaveh Darafsheh (NASA Langley Research Center) for his help with testing Copilot. In addition numerous people have helped with smaller things, reporting bugs etc. Thanks to all of them!