Dynamic memory allocation in C++ S_functions

Hey there, My question is pretty straightforward: Is it possible/allowed to reallocate Memory in S-functions written in C++. I have an array in my S-Function that buffers data for me and I was wondering if I need to allocate the buffer big enough in my mdlStart function or if I could start off with a small buffer and use realloc() to make it bigger if needed at run-time. While researching this Problem I found some unclear answers to that. Some say, that dynamic allocation is not allowed in Simulink, but I couldn't find any specific Information about this in the documentation. Thanks in advance

[Dhruvesh Patel]

One option could be to use the PWORK Vector . You would need to allocate/reallocate (using malloc/realloc) in your C++ code and give the pointer to this memory to PWORK Vector which will hold on to it throughout the simulation. Refer to (2) of the following answer.

How can I dynamically grow the work vector in my level 2 MATLAB file S-function in Simulink 6.5 (R2006b)?

Please provide some example code describing what you intend to archive. It would lead to a more precise answer.

[Lukas Abelt]

Hello Dhruvesh,

This is basically what I am currently doing. I am allocating my Array in the mdlStart function, store the pointer in the PWork vector and access this pointer in my mdlOutputs.

I just wanted to get some Information if the Simulink engine allows dynamic Memory (re)allocation during Simulation as some sources I found during my Research on this topic state explicitely, that dynamic Memory (re)allocation during Simulation is not allowed.

Can I assume from your post, that there are no limitations (despite the usual ones) on using malloc/realloc during Simulation?

I am attaching a snippet of my code how I allocate my buffer and store/Access it from the PWorks vector in my current Version. If possible I would like to adapt this code to dynamically allocate a greater buffer if needed (and not just use a big buffer from the beginning)

#define BUFFERSIZE 65535
...

static void mdlStart(SimStruct *S){
    ...
    /* Allocate memory for PWork values */
    void *data_buffer = calloc(BUFFERSIZE, sizeof(char));    
    ...
    ssSetPWorkValue(S, DATA_BUFFER, data_buffer);  
}
...

static void mdlOutputs(SimStruct *S){
...
char *data_buffer = (char *)ssGetPWorkValue(S, DATA_BUFFER);
//Do something with data_buffer
}

//Of course free() the allocated memory in mdlTerminate()

Thank you in advance!

Lukas