> And the description of str doesn't specify any rotation.  To be
> honest, I'm not sure what the expected behaviour there is (though
> actually doing an unaligned store might be hard for the CPU -- and
> strh special-cases the odd case).

Its architecturally undefined.  Many implementations of STR just put the 
word out on the data bus with no rotation, but there is no requirement for 
it to be like this.