MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Guide de l'utilisateur télécharger pdf (Page 91)

Overview of the C MEX S-Function Routines

3-47

This code retrieves the FILE pointer from the pointer-work vector and passes it

fclose to close the file:

static void mdlTerminate(SimStruct *S)

{

if (ssGetPWork(S) != NULL) {

FILE *fPtr;

fPtr = (FILE *) ssGetPWorkValue(S,0);

if (fPtr != NULL) {

fclose(fPtr);

}

ssSetPWorkValue(S,0,NULL);

}

Note If you are using mdlSetWorkWidths, then any work vectors you use in

your S- function should be set to

DYNAMICALLY_SIZED in mdlInitializeSizes,

even if the exact value is known before

mdlIntializeSizes is called. The size

to be used by the S-function should be specified in mdlSetWorkWidths.

The synopsis is:

#define MDL_SET_WORK_WIDTHS /* Change to #undef to remove function. */

#if defined(MDL_SET_WORK_WIDTHS) && defined(MATLAB_MEX_FILE)

static void mdlSetWorkWidths(SimStruct *S)

{

}

#endif /* MDL_SET_WORK_WIDTHS */

For an example, see matlabroot/simulink/src/sfun_dynsize.c.

Memory Allocation

When creating an S-function, itis possiblethat theavailableworkvectors don’t

provide enough capability. In this case, you will need to allocate memory for

each instance of your S-function. The standard MATLAB API memory

allocation routines (

mxCalloc, mxFree) should not be used with C MEX

S-functions. The reason is that these routines are designed to be used with

MEX-files that are called from MATLAB and not Simulink. The correct

approach for allocating memory is to use the

stdlib.h (calloc, free) library

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MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Guide de l'utilisateur Page 91