Do you want the least significant 1 bit set? Then use trailing_zeros(x). (I use that a lot for packing floating point values, which are right justified in the word (if you consider the msb as being the rightmost bit). If you want the most significant 1 bit set, then leading_zeros(x) (which other people have already mentioned).
On Thursday, August 11, 2016 at 7:48:08 PM UTC+2, jw3126 wrote: > > I have a bitstype and want to know the number of ones in its bit > representation as well as the first bit. How to accomplish these in a > performant way? >
