When using bitwise operations in Stateflow blocks,

Normally, bitwise operations are not meaningful on signed integers. Undesired behavior can occur. For example, a shift operation might move the sign bit into the number, or a numeric bit into the sign bit.

By Task > Modeling Standards for MAAB > Stateflow > Check for bitwise operations in Stateflow charts

• IEC 61508-3, Table A.3 (3) 'Language subset'
  IEC 61508-3, Table A.3 (2) 'Strongly typed programming language'

• ISO/DIS 26262-6, Table 1 (b) 'Use of language subsets'
  ISO/DIS 26262-6, Table 1 (c) 'Enforcement of strong typing'

• DO-178B, Section 6.3.1b 'High-level requirements are accurate and consistent'
  DO-178B, Section 6.3.1e 'High-level requirements conform to standards'
  DO-178B, Section 6.3.1g 'Algorithms are accurate'
  DO-178B, Section 6.3.2b 'Low-level requirements are accurate and consistent'
  DO-178B, Section 6.3.2e 'Low-level requirements conform to standards'
  DO-178B, Section 6.3.2g 'Algorithms are accurate'

• MISRA-C:2004, Rule 12.7 'Bitwise operators shall not be applied to operands whose underlying type is signed'

To support bounded function call behavior, avoid using design patterns that include unbounded recursive behavior. Recursive behavior is bound if you do the following:

This rule only applies if a chart is a classic Stateflow chart. If hisf_0001: Mealy and Moore semantics is followed, recursive behavior is prevented due to restrictions in the chart semantics. Additionally, you can detect the error during simulation by enabling the Stateflow diagnostic Detect Cycles.

• IEC 61508-3, Table B.1 (6) 'Limited use of recursion'

• ISO/DIS 26262-6, Table 9 (j) 'No recursions'

• DO-178B, Section 6.3.1b 'High-level requirements are accurate and consistent'
  DO-178B, Section 6.3.1e 'High-level requirements conform to standards'
  DO-178B, Section 6.3.1g 'Algorithms are accurate'
  DO-178B, Section 6.3.2b 'Low-level requirements are accurate and consistent'
  DO-178B, Section 6.3.2e 'Low-level requirements conform to standards'
  DO-178B, Section 6.3.2g 'Algorithms are accurate'

• MISRA-C:2004, Rule 16.2

There are multiple patterns in Stateflow that can result in unbounded recursion.

Recursive Function Calls

When the default state A is entered, event Evn is broadcast in the entry action of A. Evn results in a recursive call of the interpretation algorithm. Since A is active, the outgoing transition of A is tested. Since the current event Evn matches the transition event (and because of the absence of condition) the condition action is executed, broadcasting Evn again. This results in a new call of the interpretation algorithm which repeats the same sequence of steps until stack overflow.

Recursive Function Calls

To enhance clarity and prevent the generation of unreachable code,

You can use this guideline to maintain a modeling language subset in high-integrity projects.

• DO-178B, Section 6.3.1b 'High-level requirements are accurate and consistent'
  DO-178B, Section 6.3.1d 'High-level requirements are verifiable'
  DO-178B, Section 6.3.1e 'High-level requirements conform to standards'
  DO-178B, Section 6.3.2b 'Low-level requirements are accurate and consistent'
  DO-178B, Section 6.3.2d 'Low-level requirements are verifiable'
  DO-178B, Section 6.3.2e 'Low-level requirements conform to standards'

Transitions that loop out of the parent of the source and destination objects are typically unintentional and cause the parent to deactivate.

You can use this guideline to maintain a modeling language subset in high-integrity projects.

• DO-178B, Section 6.3.1b 'High-level requirements are accurate and consistent'
  DO-178B, Section 6.3.1e 'High-level requirements conform to standards'
  DO-178B, Section 6.3.1g 'Algorithms are accurate'
  DO-178B, Section 6.3.2b 'Low-level requirements are accurate and consistent'
  DO-178B, Section 6.3.2e 'Low-level requirements conform to standards'
  DO-178B, Section 6.3.2g 'Algorithms are accurate'

To enhance traceability between generated code and a model,

Add comments to the following Stateflow objects:

In R2008b and higher:

• Transitions

In R2008a and lower:

• Transitions

• States

You can us this guideline to maintain a modeling language subset in high-integrity projects.

• DO-178B, Section 6.3.4e 'Source code is traceable to low-level requirements'

To avoid creating diagrams that are hard to understand,

You can use this guideline to maintain a modeling language subset in high-integrity projects.

In the following example, when Out_A is 4, both parent states (A_Parent and B_Parent) are reentered. Reentering the parent states resets the values of Out_A and Out_B to zero.

To avoid creating diagrams that are confusing and include transition paths without benefit,

You can use this guideline to maintain a modeling language subset in high-integrity projects.

• DO-178B, Section 6.3.1b 'High-level requirements are accurate and consistent'
  DO-178B, Section 6.3.1e 'High-level requirements conform to standards'
  DO-178B, Section 6.3.2b 'Low-level requirements are accurate and consistent'
  DO-178B, Section 6.3.2e 'Low-level requirements conform to standards'

To facilitate strong data typing,

Explicitly type cast variables and parameters of different data types in:

• Transition evaluations

• Transition assignments

• Assignments in states

The Stateflow software automatically casts variables of different type into the same data type. This guideline helps clarify data types of the intermediate variables.

• DO-178B, Section 6.3.1b 'High-level requirements are accurate and consistent'
  DO-178B, Section 6.3.1e 'High-level requirements conform to standards'
  DO-178B, Section 6.3.1g 'Algorithms are accurate'
  DO-178B, Section 6.3.2b 'Low-level requirements are accurate and consistent'
  DO-178B, Section 6.3.2e 'Low-level requirements conform to standards'
  DO-178B, Section 6.3.2g 'Algorithms are accurate'

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