MathWorks Simulink Stateflow

fsmc provides native ingestion and roundtrip serialization for MathWorks Simulink Stateflow models exported to XML or JSON formats. This enables fsmc to act as an open-source, vendor-independent bridge from Simulink Stateflow designs to zero-allocation C++17/20, formal model checkers, and MBSE specifications without requiring commercial code generation toolboxes.

---

1. Supported Stateflow Elements

fsmc maps the core hierarchical statechart constructs of MathWorks Stateflow directly into its unified FsmIr:

Stateflow Construct	XML Representation	fsmc Semantic Mapping
Chart Root	<Stateflow><machine><chart name="...">	Root FsmIr model and state machine class
Exclusive State (OR)	<state name="..." decomposition="EXCLUSIVE_OR">	Standard atomic or composite state
Parallel State (AND)	<state name="..." decomposition="PARALLEL_AND">	Orthogonal parallel execution region
History Junction	<junction type="HISTORY">	Deep history pseudostate (DeepHistory)
Transitions	<transition><src id="..."><dst id="...">	Directed TransitionEdge
Transition Label	<labelString>Event [Guard] / { Action }</labelString>	Trigger, guard condition, and action effect
Temporal Logic	after(N, sec), after(N, msec)	Deterministic timed transition (TimeTrigger)
State Actions	en: entryAction(); du: during(); ex: exit();	State entry, continuous step, and exit actions

---

2. Transition Label Syntax & Temporal Logic

Stateflow utilizes a compact, expressive label format for transitions:

trigger [guard] / { action }

fsmc automatically decomposes this label format: * Trigger: Event name (e.g., EvArmed, StepTick). * Guard: Boolean expression enclosed in square brackets (e.g., [in.sensor_altitude > 1000.0]). * Action Effect: C-like assignment or routine call enclosed in curly braces (e.g., /{ reg.mode = 1; }).

Temporal Logic Triggers

Simulink Stateflow's temporal operators are natively recognized and translated into deterministic timer triggers:

• after(500, msec) or after(0.5, sec): Translated into a TimeTrigger with duration 500ms.
• During execution, the synchronous runtime steps these timers deterministically using sm.tick(dt).

---

3. Lossless Directives in Stateflow Models

To enrich Stateflow models with hardware I/O ports, range bounds, enums, structs, and formal temporal properties (LTL/CTL), fsmc supports embedding directives inside standard XML comments:

<?xml version="1.0" encoding="UTF-8"?>
<Stateflow>
  <machine name="FlightControllerMachine">
    <!-- @fsm:enum name=FlightMode values=Idle,Arming,Cruising,Emergency -->
    <!-- @fsm:port name=sensor_altitude type=float dir=in min=0.0 max=50000.0 unit="[m]" -->
    <!-- @fsm:port name=thrust_cmd type=float dir=out min=0.0 max=100.0 unit="[%]" -->
    <!-- @fsm:register name=cycles_elapsed type=uint32_t init=0 -->
    <!-- @fsm:property name=SafeCeiling kind=Safety ltl="G (sensor_altitude < 50000.0)" -->

    <chart name="FlightController" initial="Preflight">
      <state name="Preflight" SSID="1">
        <labelString>en: out.thrust_cmd = 0.0;</labelString>
      </state>

      <state name="InFlight" SSID="2">
        <labelString>en: out.thrust_cmd = 75.0;</labelString>
      </state>

      <transition SSID="10">
        <src name="Preflight"/>
        <dst name="InFlight"/>
        <labelString>EvArm [in.sensor_altitude >= 0.0] / { reg.cycles_elapsed = 0; }</labelString>
      </transition>

      <transition SSID="11">
        <src name="InFlight"/>
        <dst name="Preflight"/>
        <labelString>after(30, sec)</labelString>
      </transition>
    </chart>
  </machine>
</Stateflow>

---

4. CLI Workflow & Roundtrip Serialization

Ingesting Stateflow and Generating C++ Code

fsmc automatically detects Stateflow models by extension (.slx, .sfx, .stateflow, .xml) or by inspecting file contents:

# Ingest native MathWorks Simulink .slx package directly
fsmc -i Model.slx -o Model.hpp --target cpp

# Ingest Stateflow XML and emit zero-allocation C++20 header
fsmc -i FlightController.xml -o FlightController.hpp --target cpp

# Generate C++ with active object asynchronous wrapper and MC/DC harness
fsmc -i FlightController.xml -o FlightController.hpp --emit-test-harness FlightController_mcdc_test.cpp

Direct .slx OPC Container Ingestion

fsmc includes native OPC (Open Packaging Convention) / ZIP container extraction with built-in Deflate decompression. It reads .slx models directly from disk without requiring MATLAB, Simulink, or external decompression tools like unzip: - Automatically locates and inspects simulink/stateflow.xml and simulink/blockdiagram.xml. - Streams compressed block XML and extracts charts, states, junctions, and transitions into FsmIr.

Exporting Any Model to Stateflow

You can translate models from any supported format (SysML v2, SCXML, PlantUML, Mermaid, Cameo XMI) into Stateflow XML:

# Transpile SysML v2 to MathWorks Stateflow XML
fsmc -i FlightController.sysml --export stateflow -o FlightController_sf.xml

The resulting XML can be directly imported into MathWorks Simulink or round-tripped back through fsmc without loss of structure or metadata.