MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Betriebsanweisung PDF herunterladen (Seite 178)

4 Guidelines for Writing C MEX S-Functions

4-12

* mdlInitializeSampleTimes - indicate that this S-function runs

*at the rate of the source (driving block)

static void mdlInitializeSampleTimes(SimStruct *S)

{

ssSetSampleTime(S, 0, INHERITED_SAMPLE_TIME);

ssSetOffsetTime(S, 0, 0.0);

}

* mdlOutputs - compute the outputs by calling my_alg, which

*resides in another module, my_alg.c

static void mdlOutputs(SimStruct *S, int_T tid)

{

InputRealPtrsType uPtrs = ssGetInputPortRealSignalPtrs(S,0);

real_T *y = ssGetOutputPortRealSignal(S,0);

*y = my_alg(*uPtrs[0]);

}

* mdlTerminate - called when the simulation is terminated.

static void mdlTerminate(SimStruct *S)

{

}

#ifdef MATLAB_MEX_FILE /* Is this file being compiled as a MEX-file? */

#include “simulink.c” /* MEX-file interface mechanism */

#else

#include “cg_sfun.h” /* Code generation registration function */

#endif

The S-function routine mdlOutputs contains a function call to my_alg,whichis

the C function that contains the algorithm that the S-function performs. This

isthecodefor

my_alg.c:

#include "tmwtypes.h"

real_T my_alg(real_T u)

{

return(u * 2.0);

}

The wrapper S-function (wrapsfcn) calls my_alg, which computes u * 2.0.To

build

wrapsfcn.mex, use the following command:

mex wrapsfcn.c my_alg.c

Place the call to

my_alg in

mdlOutputs.

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MATLAB SIMULINK 7 - DEVELOPING S-FUNCTIONS Betriebsanweisung Seite 178