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Integrate External C++ Object Methods

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Integrate legacy C++ object methods by using the Legacy Code Tool.

With the Legacy Code Tool, you can:

  • Provide the legacy function specification.

  • Generate a C++ MEX S-function that calls the legacy code during simulation.

  • Compile and build the generated S-function for simulation.

  • Generate a block TLC file and optional rtwmakecfg.m file that calls the legacy code during code generation.

Provide the Legacy Function Specification

Functions provided with the Legacy Code Tool take a specific data structure or array of structures as the argument. The data structure is initialized by calling the function legacy_code() using initialize as the first input. After initializing the structure, assign its properties to values corresponding to the legacy code being integrated. The definition of the legacy C++ class in this example is:

class adder {
  private:
      int int_state;
  public:
      adder();
      int add_one(int increment);
      int get_val();
};

The legacy source code is in the files adder_cpp.h and adder_cpp.cpp.

% sfun_adder_cpp
def = legacy_code('initialize');
def.SFunctionName = 'sfun_adder_cpp';
def.StartFcnSpec  = 'createAdder()';
def.OutputFcnSpec = 'int32 y1 = adderOutput(int32 u1)';
def.TerminateFcnSpec = 'deleteAdder()';
def.HeaderFiles   = {'adder_cpp.h'};
def.SourceFiles   = {'adder_cpp.cpp'};
def.IncPaths      = {'Lct_src'};
def.SrcPaths      = {'Lct_src'};
def.Options.language = 'C++';
def.Options.useTlcWithAccel = false;

Generate an S-Function for Simulation

To generate a C-MEX S-function according to the description provided by the input argument def, call the function legacy_code() again with the first input set to sfcn_cmex_generate. The S-function calls the legacy functions during simulation. The source code for the S-function is in the file sfun_adder_cpp.cpp.

legacy_code('sfcn_cmex_generate', def);

Compile the Generated S-Function for Simulation

After you generate the C-MEX S-function source file, to compile the S-function for simulation with Simulink®, call the function legacy_code() again with the first input set to compile.

legacy_code('compile', def);

### Start Compiling sfun_adder_cpp
    mex('-I/tmp/Bdoc24b_2725827_4048235/tp88aafc20/simulinkcoder-ex06428671/Lct_src', '-I/tmp/Bdoc24b_2725827_4048235/tp88aafc20/simulinkcoder-ex06428671', '-c', '-outdir', '/tmp/Bdoc24b_2725827_4048235/tp92af3f10_a09b_4d93_b2e8_3165c419dd33', '/tmp/Bdoc24b_2725827_4048235/tp88aafc20/simulinkcoder-ex06428671/adder_cpp.cpp')
Building with 'g++'.
MEX completed successfully.
    mex('sfun_adder_cpp.cpp', '-I/tmp/Bdoc24b_2725827_4048235/tp88aafc20/simulinkcoder-ex06428671/Lct_src', '-I/tmp/Bdoc24b_2725827_4048235/tp88aafc20/simulinkcoder-ex06428671', '-cxx', '/tmp/Bdoc24b_2725827_4048235/tp92af3f10_a09b_4d93_b2e8_3165c419dd33/adder_cpp.o')
Building with 'g++'.
MEX completed successfully.
### Finish Compiling sfun_adder_cpp
### Exit

Generate a TLC Block File for Code Generation

After you compile the S-function and use it in simulation, you can call the function legacy_code() again. Set the first input to sfcn_tlc_generate to generate a TLC block file that supports code generation through Simulink® Coder™. If the TLC block file is not created and you try to generate code for a model that includes the S-function, code generation fails. The TLC block file for the S-function is sfun_adder_cpp.tlc.

legacy_code('sfcn_tlc_generate', def);

Generate an rtwmakecfg.m File for Code Generation

After you create the TLC block file, you can call the function legacy_code() again. Set the first input to rtwmakecfg_generate to generate an rtwmakecfg.m file that supports code generation through Simulink® Coder™. If the required source and header files for the S-function are not in the same folder as the S-function, and you want to add these dependencies in the makefile produced during code generation, generate the rtwmakecfg.m file.

legacy_code('rtwmakecfg_generate', def);

Generate Masked S-Function Block for Calling the Generated S-Function

After you compile the C-MEX S-function source, you can call the function legacy_code() again. Set the first input to slblock_generate to generate a masked S-function block that is configured to call that S-function. The software places the block in a new model. You can copy the block to an existing model.

legacy_code('slblock_generate', def);

Show the Generated Integration with Legacy Code

The model LctExternalCodeImportCpp shows integration with the legacy code.

open_system('LctExternalCodeImportCpp')
sim('LctExternalCodeImportCpp')

ans =

    '
     ### Start Compiling sfun_adder_cpp
         mex('-I/tmp/Bdoc24b_2725827_4048235/tp88aafc20/simulinkcoder-ex06428671/Lct_src', '-I/tmp/Bdoc24b_2725827_4048235/tp88aafc20/simulinkcoder-ex06428671', '-c', '-outdir', '/tmp/Bdoc24b_2725827_4048235/tpa89cbee0_a040_4783_a0b8_35ee6a93b8eb', '/tmp/Bdoc24b_2725827_4048235/tp88aafc20/simulinkcoder-ex06428671/adder_cpp.cpp')
     Building with 'g++'.
     MEX completed successfully.
         mex('sfun_adder_cpp.cpp', '-I/tmp/Bdoc24b_2725827_4048235/tp88aafc20/simulinkcoder-ex06428671/Lct_src', '-I/tmp/Bdoc24b_2725827_4048235/tp88aafc20/simulinkcoder-ex06428671', '-cxx', '/tmp/Bdoc24b_2725827_4048235/tpa89cbee0_a040_4783_a0b8_35ee6a93b8eb/adder_cpp.o')
     Building with 'g++'.
     MEX completed successfully.
     ### Finish Compiling sfun_adder_cpp
     ### Exit
     '

See Also

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