In the IO_GPOIOBase.h file, on line 127, instead of
uint16_t mask = 1 << pin;
it should be
uint64_t mask = 1 << pin;
to ensure the claimed (in line 30) support for up to 64 pins.
But what if I need a driver for a controller emulating an I2C expander with 128, 256, or more pins?