reactor-uc

reactor-uc is a task scheduling runtime implementing the reactor model-of-computation target at embedded and resource-constrained systems.

Getting started

NB: reactor-uc is still work-in-progress and sevearal reactor features are not supported yet. Moreover, the runtime has not been thoroughly tested so if you find any bugs or issues, please report them.

Setup the environment

source env.bash

Initialize submodules

git submodule update --init

Compile and run unit tests:

make test

Examples

Linux/POSIX

make examples
build/examples/posix/timer_ex

Zephyr

Compile and run a simple test on Zephyr. This requires a correctly configured Zehyr environment, with West installed in a Python virtual environment which is activated. Inspect .github/actions/zephyr/action.yml for an example of how to setup your Zephyr workspace.

First a simple HelloWorld on the qemu_cortex_m3 target:

cd examples/zephyr/hello
west build -b qemu_cortex_m3 -p always -t run

Then a simple blinky targeting NXP FRDM K64F. This will run with most boards supporting Zephyr that has a user LED.

cd examples/zephyr/blinky
west build -b frdm_k64f -p always
west flash

For more information on running LF programs using the reactor-uc runtime on Zephyr take a look at this template: https://github.com/lf-lang/lf-west-template/tree/reactor-uc

RIOT

Compile and run a simple blinky example on RIOT. This requires a correctly configured RIOT environment. Make sure that the environment variable RIOTBASE points to a RIOT codebase.

cd examples/riot/blinky
make BOARD=native all term

Pico

Download pico-sdk and define PICO_SDK_PATH as an environmental variable.

cd examples/pico
cmake -Bbuild
cd build
make

Lingua Franca

NB: We are currently not keeping lfc up-to-date. We will probably do so again when the APIs have stabilized.

We have copied a very limited version of the Lingua Franca Compiler (lfc) into ~/lfc of this repo. In the future, the reactor-uc specific code-generation will be merged back upstream. By sourcing env.bash or env.fish the Lingua Franca Compiler will be aliased by lfcg for Lingua Franca Generator since this limited version mainly oes does code-generat

cd examples/lf
lfcg src/HelloUc.lf

Since a target platform is not specified, we will target POSIX in which case lfc will generate a main function and invoke CMake directly on the generated sources. Run the program with:

bin/HelloUc

Goals

• Incorporate unit testing and test-driven development from the start
• Optimized for single-core 32-bit systems
• Backend for LF
• Standalone library
• Use clang-format and clang-tidy to write safe code from the start.
• CMake-based
• Optimized for single-threaded runtime, but support for federated execution which enable distributed embedded systems.
• Avoid malloc as much as possible (or entirely?)

References

reactor-uc draws inspiration from the following existing open-source projects:

• reactor-cpp
• reactor-c
• qpc
• ssm-runtime

Troubleshooting

Formatting

We are using clang-format version 18.1.3 which is default with Ubuntu 24.04 for formatting in CI.

LFC

If you get the following CMake error when calling lfc/bin/lfc-dev

CMake Error at CMakeLists.txt:7 (message):
  Environment variable REACTOR_UC_PATH is not set.  Please source the
  env.bash in reactor-uc.

Please source env.bash or env.fish.