REXIS (Real-time EXecutive for Intelligent Systems) is a message passing executive kernel. Its main features are:

  1. Round robin priority based preemptive scheduling, providing fast real-time performance.
  2. Message passing primitives provide synchronizing and interprocess communication capabilities, minimizing the problem with asynchronous events and data copying.
  3. Mutex for exclusive resource access.
  4. Both message passing and mutex use priority inheritance to prevent deadlocks due to priority inversion.
  5. Efficient use of Cortex MCU resources. Kernel functions run in handler mode with the system stack, and tasks run in thread/user mode with each task having its own process stack.
  6. Includes memory allocator with resource automatically tracked by the executive, and allocated resource can be reclaimed via a single kernel call.
  7. Kernel calls done with SVC instructions.

More information will be available shortly. The API is documented here: 

REXIS API in browseable Doxygen format V0.10 2018/4/11 available here.