Neither, on Linux. 
More seriously, I have no idea for Windows, but the relevant code is in the ControllerInterface: https://github.com/dolphin-emu/dolphin/tree/master/Source/Core/InputCommon/ControllerInterface

More seriously, I have no idea for Windows, but the relevant code is in the ControllerInterface: https://github.com/dolphin-emu/dolphin/tree/master/Source/Core/InputCommon/ControllerInterface
