The MMIO access framework consists of an abstraction for a contiguous
MMIO area with a base address set dynamically. Within this class 'Mmio'
are declarations for 'Register' and 'Subreg'. These two can be
parameterized statically via template parameters to create arbitrary
MMIO structures.
Whereas 'Register' relies to a POD like subregion of 'Mmio', 'Subreg'
relies to a MMIO region within a specific 'Register' and therefore is
smaller or equal then the storage type of its superior 'Register'.
Furthermore with 'Reg_array' and 'Subreg_array', there exists the
possibility to handle arrays of uniform contiguous registers or subregs
by index. 'Subreg_array' therefore abstracts from the width boundary of
its superior 'Register' and handles a steady distance between its
members in addition. Both also check array size limits.
Related to issue #69.
