I am working with Matlab / Simulink, and I would need to copy/paste the SPI.h and wire.h for the Arduino Due.
I could retrieve it from Arduino github after looking for a while in my installation folder.
Some people suggest it is in C:\Program Files (x86)\Arduino\hardware\arduino\sam
However this folder has not been created once in installed the Arduino Due board via the board manager.
I was able to compile a dummy code from the Arduino IDE using the SPI.h library. So I presume that SPI.h was properly installed.