Issue when converting between multiple data types

calling somebody else's code a mess was what I meant by not being too helpful.

I'm a bit of a purist and using an unsigned type just to avoid typing is not a good reason (to me). But using an unsigned for the lsb an msbd makes sense, then again the source and destination are perfectly represented by a std_logic_vector. Now alegomaster is developing an Alu (I believe) so the lsb and msb are probably slices of an std_logic_vector, so it comes down to deciding where to put the conversion function, at the 'slicing them' of at 'using them'.