Andreas Klein wrote:
Dear admin.
I am trying to post to the boost-mailing list. I get a replay that the message was recived, but it do not appear on the list. Can you help me?
Best wishes Andreas Klein
------------------------------------------------------------------------ Dear boost developers,
I checked the implementation of boost::dynamic_bitset::count
and find that it uses a table look up.
This is not optimal.
First on 64-bit machines divide-and-conquer algorithms are faster than table look up and save even memory.
Second if the bitset contains several words, there are for both 32 and 64 bit machines population count algorithms that are faster than the simple loop over all words used by boost.
Together with Y. Edel I developed a new version,which saves 60% against the simple algorithm. We put the code online (http://cage.ugent.be/~klein/popc.html). A disadvantage of our implementation is that we relay on aggressive optimization (-O3) of the compiler.
If you are searching a compromise between speed and code complexity. The first iteration of the Harley-Seal-method (25% faster than the simple loop) would be a candidate.
You find this and other population count algorithms on our homepage, too.
If there is interest I can add one of the advance algorithms in boost.
Best wishes Andreas Klein
Hi, Andreas. The message that you are reposting here successfully arrived first time. You must have "Receive your own posts to the list?" flag turned off. You can turned it on through the web interface. Here http://lists.boost.org/mailman/options.cgi/boost HTH, Dmitry