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re-worked "preemption-threshold" implementation

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QP Framework

What's New?

View QP/C Revision History at:

NOTE: If you're interested in the latest QP/C version from GitHub, it is recommened that you clone this repo like that:

git clone --recurse-submodules --depth 1

Alternatively, you can also download the latest QP/C Release.

Getting Started with QP/C

The most recommended way of obtaining QP/C is by downloading the QP-bundle, which includes QP/C as well as the QM modeling tool and the QTools collection. The main advantage of obtaining QP/C bundled together like that is that you get all components, tools and examples ready to go.

Getting Started Resources

About QP/C

QP/C (Quantum Platform in C) is a lightweight, open source Real-Time Embedded Framework (RTEF) for building modern embedded software as systems of asynchronous, event-driven active objects (actors). The QP/C framework is a member of a QP family consisting of QP/C and QP/C++ frameworks, which are strictly quality controlled, thoroughly documented, and commercially licensable.

Safer Model of Concurrency

The QP framework family is based on the Active Object (actor) design pattern, which inherently supports and automatically enforces the following best practices of concurrent programming:

  • Keep data isolated and bound to active objects' threads. Threads should hide (encapsulate) their private data and other resources, and not share them with the rest of the system.

  • Communicate among active object threads asynchronously via event objects. Using asynchronous events keeps the threads running truly independently, without blocking on each other.

  • Active object threads should spend their lifetime responding to incoming events, so their mainline should consist of an event-loop that handles events one at a time (to completion), thus avoiding any concurrency hazards within an active object thread itself.

This architecture is generally safer, more responsive and easier to understand and maintain than the shared-state concurrency of a conventional RTOS. It also provides higher level of abstraction and the correct abstractions to effectively apply modeling and code generation to deeply embedded real-time systems.

Hierarchical State Machines

The behavior of active objects is specified in QP/C by means of Hierarchical State Machines (UML statecharts). The framework supports manual coding of UML state machines in C as well as automatic code generation by means of the free QM modeling tool.

Built-in Real-Time Kernels

The QP/C framework can run on bare-metal single-chip microcontrollers, completely replacing a traditional RTOS. The framework contains a selection of built-in real-time kernels, such as the cooperative QV kernel, the preemptive non-blocking QK kernel, and the preemptive, blocking QXK kernel that provides all the features you might expect from a traditional RTOS. Native QP ports and ready-to-use examples are provided for major CPUs, such as ARM Cortex-M (M0/M0+/M3/M4/M7).

Traditional RTOS/OS

QP/C can also work with a traditional RTOS, such as ThreadX, FreeRTOS, embOS, uC/OS-II and TI-RTOS, as well as with (embedded) Linux (POSIX) and Windows.

Popularity and Maturity

With 20 years of continuous development, over 350 commercial licensees, and many times more open source users worldwide, the QP™ frameworks are the most popular such offering on the market. They power countless electronic products ranging from implantable medical devices to complex weapon systems.

QP/C Licensing

QP/C is licensed under the sustainable dual licensing model, in which both the open source software distribution mechanism and traditional closed source software distribution models are combined.

NOTE: If your company has a policy forbidding open source in your product, all QP frameworks can be licensed commercially, in which case you don't use any open source license and you do not violate your policy.

QP/C Documentation

The online HTML documention for the latest version of QP/C is located at:

The offline HTML documentation for this particular version of QP/C is located in the sub-folder html. To view the offline documentation, open the file html/index.html in your web browser.

How to Get Help?

How to Help this Project?

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