Target Language Compiler

Noninlined Code Generation

1. Copy the tutorial directory tlctutorial/timestwo into your working directory. It contains a Simulink S-function, timestwo.c.

Note    The timestwo.c code is a level-2 S-function. For general information on level-2 S-functions, see the Simulink Writing S-functions documentation.

2. In the MATLAB command window, create a MEX-file for the S-function:

• mex timestwo.c
  

1. This is needed to avoid picking up the version shipped with Simulink.

3. Open the model sfun_x2.mdl, which uses the timestwo S-function. The block diagram looks like this.

4. Set up simulation parameters to use a fixed-step discrete solver with a step size of 0.01 and stop time of 10.0.
5. Go to the Advanced tab of the Simulation Parameters... dialog, and make sure that the Inline parameters box is not selected.
6. Select Generate code only from the Real-Time Workshop tab in the Simulation Parameters... dialog box. The text of the Build button will change to Generate code. Click on Generate code to generate C source for the model. In your editor, view the MdlOutputs and MdlTerminate portions of the resulting file, sfun_x2.c, shown below.

Note    In this and other code examples to follow, lines in bold type highlight statements that change significantly as you work the examples.

• ...
  /* Compute block outputs */
  void MdlOutputs(int_T tid)
  {
    /* This is a single rate system */
    (void)tid;
  
    /* Sin: '<Root>/Sine Wave' */
    rtB.Sine_Wave = rtP.Sine_Wave_Amp *
      sin(rtP.Sine_Wave_Freq * ssGetT(rtS) + rtP.Sine_Wave_Phase) +
      rtP.Sine_Wave_Bias;
  
    /* Level2 S-Function Block: <Root>/S-Function (timestwo) */
    {
      SimStruct *rts = ssGetSFunction(rtS, 0);
      sfcnOutputs(rts, tid);
    }
  
    /* Outport: '<Root>/Out1' */
    rtY.Out1 = rtB.S_Function;
  }
  
  /* Perform model update */
  void MdlUpdate(int_T tid)
  {
    /* (no update code required) */
  }
  
  /* Terminate function */
  void MdlTerminate(void)
  {
    /* Level2 S-Function Block: <Root>/S-Function (timestwo) */
    {
      SimStruct *rts = ssGetSFunction(rtS, 0);
      sfcnTerminate(rts);
    }
  }
  

1. Notice the overhead of calling the function that the S-function API necessitates (highlighted lines).

Inlining S-Functions with TLC

Why Use TLC to Implement S-functions?