Register facilities are defined in the
include/picolibrary/register.h/source/picolibrary/register.cc
header/source file pair.
The ::picolibrary::Register class is used to declare a microcontroller register that is
not reserved.
Register access is restricted to the following operations:
The ::picolibrary::Reserved_Register class is used to declare a microcontroller reserved
register.
Reserved registers cannot be accessed.