D and memory mapped devices

[Rene Zwanenburg via Digitalmars-d-learn]

On Wednesday, 14 June 2017 at 08:10:57 UTC, Russel Winder wrote:
> but the bitfields mixin template appears to do more than add 
> all the bit twiddling functions to emulate the bitfields. This 
> would appear a priori to not allow for actual memory mapped 
> devices using it, or am I missing something?

I've casted void buffers to structs containing bitfields to read 
pre-existing binary files, and that worked just fine. I don't see 
why it would be different for memory mapped devices. What do yo 
mean by 'do more'?