// the find
QuantumLeaps/qpc
QP/C Real-Time Event Framework/RTOS implements event-driven Active Object (Actor) model combined with Hierarchical State Machines. Specifically designed for embedded systems (e.g., ARM Cortex-M MCUs).
QP/C is a mature active-object framework for bare-metal and RTOS-hosted embedded C, built around Miro Samek's hierarchical state machine (HSM) model from his book. It's for firmware engineers who want structured concurrency on ARM Cortex-M (and others) without rolling their own event queues and state dispatch. Not for web/app developers; this is firmly in the MCU world.
Port coverage is genuinely broad — ARM Cortex-M/R, MSP430, RISC-V, Zephyr, FreeRTOS, ThreadX, embOS, Win32, POSIX — so you can run the same application logic across wildly different targets without touching it. The HSM implementation is proven and well-documented, with a companion book and 20+ years of production use in safety-critical systems. Three schedulers (QV cooperative, QK preemptive, QXK dual-mode) let you pick the right tradeoff for your hardware without rewriting application code. The SafeQP commercial variant with IEC/ISO certification artifacts is a legitimate path to functional safety certification, which most OSS frameworks can't offer.
The useful parts — QS spy tracing, QXK kernel, MISRA compliance scripts, full test suite — are locked behind a commercial license. The open-source GPL release is usable but hobbled for any serious product. Bug tracking and support are on SourceForge in 2026, which signals organizational priorities. The framework's design predates C11 generics and modern toolchain features heavily, so the API leans on macros and conventions that feel dated next to something like Zephyr's native actor primitives; new firmware engineers will hit a steep learning curve before writing a single state transition.