Practical UML Statecharts in C/C++
Event-Driven Programming for Embedded SystemsBy
- Miro Samek, President, Quantum Leaps, Chapel Hill, NC, USA
Practical UML Statecharts in C/C++ Second Edition bridges the gap between high-level abstract concepts of the Unified Modeling Language (UML) and the actual programming aspects of modern hierarchical state machines (UML statecharts). The book describes a lightweight, open source, event-driven infrastructure, called QP that enables direct manual coding UML statecharts and concurrent event-driven applications in C or C++ without big tools.This book is presented in two parts. In Part I, you get a practical description of the relevant state machine concepts starting from traditional finite state automata to modern UML state machines followed by state machine coding techniques and state-machine design patterns, all illustrated with executable examples. In Part II, you find a detailed design study of a generic real-time framework indispensable for combining concurrent, event-driven state machines into robust applications. Part II begins with a clear explanation of the key event-driven programming concepts such as inversion of control (Hollywood Principle), blocking versus non-blocking code, run-to-completion (RTC) execution semantics, the importance of event queues, dealing with time, and the role of state machines to maintain the context from one event to the next. This background is designed to help software developers in making the transition from the traditional sequential to the modern event-driven programming, which can be one of the trickiest paradigm shifts. The lightweight QP event-driven infrastructure goes several steps beyond the traditional real-time operating system (RTOS). In the simplest configuration, QP runs on bare-metal microprocessor, microcontroller, or DSP completely replacing the RTOS. QP can also work with almost any OS/RTOS to take advantage of the existing device drivers, communication stacks, and other middleware. The accompanying website to this book contains complete open source code for QP, ports to popular processors and operating systems, including 80x86, ARM Cortex-M3, MSP430, and Linux, as well as all examples described in the book.
Embedded programmers; real-time system architects; code developers using C or C++
Published: October 2008
- Preface PART I STATECHARTS Chapter 1 Whirlwind Tour of Programming with Statecharts1.1 Why Bother?1.2 The Traditional Event-Action Paradigm1.3 State Machines – A Better Way of Programming1.3.1 The Time Bomb Example1.3.2 The Calculator Example1.5 Object-Oriented Analogy1.6 The Event-driven Framework1.6 SummaryChapter 2 A Crash Course in Statecharts 2.1 The Essence of Finite State Machines2.2 The Essence of UML Statecharts2.3 Examples of State Models2.4 SummaryChapter 3 Standard State Machine Implementations3.1 State Machine Interface3.2 Nested switch Statement3.3 State Table3.4 State Design Pattern3.5 Optimal FSM Implementation3.6 State Machines and C++ Exception Handling 3.7 Role of Pointer-to-Member Functions3.8 Implementing Guards, Junctions, and Choice Points3.9 Implementing Entry and Exit Actions3.10 Dealing with State Hierarchy3.11 SummaryChapter 4 QEP: A Minimal Hierarchical Event Processor4.1 General Structure of the QEP Event Processor4.2 An Annotated Example (QHsm)4.3 QEP Structure4.3.1 QEP Source Code Structure4.3.2 Internal Representation of a State Machine4.3.3 Initialization of a State Machine4.3.4 Dispatching Events to a FSM4.3.5 Executing a Transition in a FSM4.3.6 Dispatching Events to a HSM4.3.7 Executing a Transition in a HSM4.3.8 Static Transition Optimization in a HSM4.4 Porting and Configuring QEP4.5 Caveats4.6 SummaryChapter 5 Implementing State Machines with QEP5.1 Implementing a HSM with QEP5.1.1 Step 1: Enumerating Signals5.1.2 Step 2: Defining Events5.1.3 Step 3: Defining the QCalc State Machine5.1.4 Step 4: Declaring the QCalc States5.1.5 Step 5: Initializing the HSM5.1.6 Step 6: Implementing the State Handler Functions5.2 Implementing a FSM with QEP2.5 Pitfalls to Avoid While Coding State Machines with QEP2.5.1 Incomplete State Handlers 2-372.5.2 Confusing Statecharts with Flowcharts 2-382.5.3 Ill-Formed State Handlers 2-392.5.4 Suboptimal Signal Granularity 2-422.5.5 Violating the Run To Completion Semantics 2-424.6 SummaryChapter 6 State Patterns6.1 Ultimate Hook6.2 Reminder6.3 Deferred Event6.4 Orthogonal Component6.5 Transition to History6.6 SummaryPART II EVENT-DRIVEN FRAMEWORKChapter 7 QF: A Minimal Event-Driven Embedded Framework7.1 Conventional Approach to Multithreading7.2 Computing Model of QF7.3 Annotated Example7.3.1 The ?Airplane in the Tunnel? Game7.3.2 The Active Object Design7.3.3 The Implementation7.3.4 The Port for ARM Cortex-M37.3.5 Testing7.4 SummaryChapter 8 Design of QF8.1 Handling Errors and Exceptional Conditions8.2 Memory Management8.3 Mutual Exclusion and Blocking8.4 Active Objects8.5 Event Management in QF8.6 Event Delivery Mechanisms in QF8.9 Deferring and Recalling Events in QF8.7 Time Events8.8 SummaryChapter 9 Implementation of QF9.1 Code Organization9.2 Critical Section in QF9.3 General QF Policies Enforced by Assertions9.4 Active Object class9.5 Native QF Event Queue9.6 Native QF Memory Pool9.7 Native QF Priority Set9.8 Native QF SchedulerChapter 10 Porting QF10.1 QF Porting Guide10.2 QF on Bare-Metal Targets (the Vanilla Port)10.3 Using QF with a preemptive Real-Time Kernel (µC/OS-II)10.4 QF port to a POSIX-Compliant OS (Linux)10.5 SummaryChapter 11 Conclusion11.2 Rules for Developing Event-Driven Embedded Applications11.3 Heuristics11.4 Sizing Event Queues and Event Pools11.5 System Integration11.6 Summary of Key Elements11.7 An InvitationAppendix A QK: A Single-Stack Preemptive KernelA.2 Run-to-Completion ProcessingA.3 Synchronous and Asynchronous PreemptionsA.4 Stack UtilizationA.4 Comparison with a Traditional RTOSA.5 SummaryAppendix B QS: Software Tracing for Event Driven SystemsB.1 Software Tracing ConceptsB.2 Structure of QS Trace RecordsB.3 QS FiltersB.4 QS Data ProtocolB.5 QS Trace BufferB.6 Configuring and Porting QSB.7 SummaryAppendix C Inheriting Entire State Models in C++C.1 Statechart Refinement Example in C++C.3 CaveatsC.4 SummaryAppendix D Guide to Notation D.1 Class DiagramsD.2 Statechart DiagramsD.3 Sequence DiagramsD.4 Timing DiagramsAppendix E CD-ROME.1 Source Code StructureE.2 InstallationE.3 LicensingE.4 Answers to the ExercisesE.5 QP Reference Guide (Doxygen)E.6 Resources BibliographyIndex