Enhancement: RmwNorFlash

[MathiasKoch]

This PR implements RMW helpers for Nor flashes.

It was extracted from the previous PR #12, in order to land the traits and release them faster.

[Sympatron]

I like the approach. Especially that the merge_buffer does allow you to offload the merge process off the stack.

I am not a big fan of the overlaps() function, because it is not very readable / unclear what's going on at first. On the other hand it makes the implementation quite concise. So I have no strong opinion either way.

Currently every write out of bounds is just ignored. Returning an error might be better, but I think you would have to wrap the Storage's Error type to do that.

[MathiasKoch]

I am not a big fan of the overlaps() function, because it is not very readable / unclear what's going on at first. On the other hand it makes the implementation quite concise. So I have no strong opinion either way.

I have the exact same reservation, thus the remark here:

embedded-storage/src/iter.rs

Line 34 in abcbd3d

// TODO: This might be possible to do in a smarter way?

So anything cleaner or easier to read is more than welcomed!

[MathiasKoch]

Could we merge and release this PR as is? Or do any of you have any objections, nit-picks or similar?
@Dirbaio @eldruin @Sympatron

[Sympatron]

I'd say we can. My main concern was that writes out of bounds are just silently ignored, but this could probably be fixed in a separate PR.