StackOverflow exception when using Matlab Coder ?

Hello,

I'm a new user of Matlab Coder and I try to translate my Matlab code in C. My matlab code uses the Image toolbox, and in the entry-point function, I have a buffer of 1920*1080 pixels. So, when I generate the C code, the function has "const unsigned int buffer[2073600]" as an entry-point and I think that is the cause of the exception. So, how can I said to matlab coder to not write in the stack and take a pointer in entry-point ? Thank you for this community,

Baptiste

[Walter Roberson]

I suspect you might need to use coder.varsize

http://www.mathworks.com/help/fixedpoint/ug/defining-variable-size-data-for-code-generation.html

Answer 1

[Baptiste PERRIN]

Hi Vidya, Thank you for your answer. I actually solved my problem: in a function we cannot have a temporary variable with a memory allocation bigger than 4Kb (I think), and I had 1920*1080 images. So I found the option of dynamic allocation in the settings of Matlab Coder and now it works.

Thank you,

Baptiste

Answer 2

[Vidya Viswanathan]

Hi Baptiste,

As per my understanding, arrays are always passed by reference in C programming (by default). For example, consider the following code that is generated from a MATLAB function that accepts a matrix of size 1920 x 1080 as input and returns a matrix of the same size:

void MultBy2(const double u[2073600], double y[2073600])
{
int i0;
for (i0 = 0; i0 < 2073600; i0++) {
  y[i0] = u[i0] * 2.0;
}
}

Although the argument in the function is of the form "const double u[2073600]" rather than "const double* u[2073600]", the function that calls "MultBy2" (after creating an array of dimensions 1920 x 1080 and passing the name of the array) would still pass the array by reference (because the name of the array is a pointer to the first location of the array). Therefore, I feel that there would be no variable created in the stack.

I am not sure if this answers your question. I apologise if I have misunderstood your query. It would be very helpful if you could post the exact error message that you are receiving.

Regards,

Vidya