How can I generate a C function from a subsystem?

Hi everyone!

I want to create a C function from a subsystem. The goal is to create a nice GUI application in C/C++ for control applications, while using Simulink to create the PID regulators.

But let's just say that the subsystem contains a discrete integrator, and its sample time is set to 0.1s. How can I generate, or rather call the function that Simulink Coder generates?

Let the blocks name be MyIntegrator.

I checked Treated as atomic and packaging as Reusable function.

I want to generate a function, something like:

double MyIntegrator(double input)

and when called, it would return the current output of the integrator block.

Of course I would be responsible for calling it with the period.

How can I achieve this functionality using Simulink Coder?

Do I need to call the ..._step() fuction periodically, while updating the ..._U - input block? And then read the ..._Y block for the output?