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Code interface packaging

Package generated code interface as reusable or nonreusable functions or as a C++ class

Model Configuration Pane: Code Generation / Interface


The Code interface packaging parameter specifies how the code generator packages generated C or C++ interface code.


Nonreusable function (default) | Reusable function | C++ class
Nonreusable function

Generates nonreusable code. The code generator allocates model data structures statically. Generated entry-point functions access the data structures directly.

This is the default setting when Language is set to C.

Selecting this value enables the Classic call interface parameter.

Reusable function

Generates reusable, multi-instance code that is reentrant.

  • The generated model.c source file contains an allocation function that dynamically allocates model data for each instance of the model.

  • The generated code passes the real-time model data structure in, by reference, as an argument to entry-point functions.

  • The code generator exports the real-time model data structure in the model.h header file.

Selecting Reusable function:

  • Enables the Multi-instance code error diagnostic parameter.

  • Does not change the code generated for function-call subsystems.

If the System target file parameter is set to an ERT-based system target file:

  • This Reusable function setting is not supported if the model is configured with a service code interface.

  • Selecting Reusable function enables parameters Use dynamic memory allocation for model initialization and Pass root-level I/O as.

    • Use Use dynamic memory allocation for model initialization to control whether to generate an allocation function.

    • Use Pass root-level I/O as to control how root-level input and output arguments are passed to the reusable model entry-point functions. You can include the arguments in the real-time model data structure that is passed to the functions, pass the arguments individually, or pass the arguments as references to input and output structures.

  • You can select Reusable function when generating a static ert_main.c module, if you do the following:

    • Select the Use dynamic memory allocation for model initialization parameter.

    • Set the Pass root-level I/O as parameter to Part of model data structure.

  • You cannot select Reusable function if you:

    • Customize the model_step function prototype of a model that passes root-level I/O as a structure reference or part of the model data structure.

    • Select subsystem block parameter Function with separate data.

    • Use a subsystem that:

      • Has multiple ports that share source.

      • Has a port that is used by multiple instances of the subsystem and has different sample times, data types, complexity, frame status, or dimensions across the instances.

      • Has output marked as a global signal.

      • For each instance contains identical blocks with different names or parameter settings.

C++ class

Generates a C++ class interface for the model. The generated interface encapsulates required model data into C++ class attributes and model entry point functions into C++ class methods.

To enable this value, set the Language parameter to C++. When Language is set to C++, this value is the default setting.

For a model configured with a service code interface, this parameter setting is not relevant and, therefore, is not supported.

Selecting C++ class:

  • Enables the Multi-instance code error diagnostic parameter.

  • Disables the Classic call interface parameter.


  • The code generator exports entry-point functions in model.h. To call the entry-point functions from user-written code, add an #include model.h directive to the code.

  • When you select Reusable function, the code generator generates a pointer to the real-time model object (model_M).

  • When you select Reusable function and set the Multi-instance code error diagnostic parameter to Warning or None, the code generator might generate code that compiles but is not reentrant. For example, if a signal, a DWork structure, or parameter data has a storage class other than Auto, the code generator produces global data structures.

Recommended Settings

DebuggingNo impact
TraceabilityNo impact
EfficiencyReusable function or C++ class
Safety precautionNo impact

Programmatic Use

Parameter: CodeInterfacePackaging
Type: character vector
Value: 'C++ class' | 'Nonreusable function' | 'Reusable function'
Default: 'Nonreusable function' if TargetLang is set to 'C'; 'C++ class' if TargetLang is set to 'C++'

Version History

Introduced in R2014a