Accessing Arduino registers like DDRX and PINX

Hi everyone. Trying to access some registers like PORTX, PINX, etc. on Arduino.

A practical example why;

To set multiple digital pins at once using PORTX, or

To get multiple digital pins' values at once by reading PINX.

For instance, I have an external 8bits counter and want to get that 8 bits data all at once, not just reading 8 bits one by one and do maths to combine them.

Normally I would get this just by reading PIND register for ex. How could I do this in Matlab and/or Simulink?

Thanks