On 6/17/07, Ron Johnson <ron.l.johnson@cox.net> wrote:
> On 06/16/07 17:05, Alexander Staubo wrote:
> > On 6/16/07, Ron Johnson <ron.l.johnson@cox.net> wrote:
> >> > Hardware acceleration for quickly counting the number of
> >> > set/unset/matching bits?
> >>
> >> x86 doesn't already do that?
> >
> > I don't think so. The fastest way, I believe, is to use precomputed
> > lookup tables. Same for finding the least/most significant set/unset
> > bit, and other operations useful for dealing with bit vectors.
>
> A couple of new AMD Barcelona opcodes might help do that:
>
> http://www.anandtech.com/showdoc.aspx?i=2939&p=6
Very cool. Thanks for the pointer.
Alexander.
