http://3cbzkrvakrpetjjppdwzbzqrlkmzatjs7jbyazap5gwutj32gcltjpqd.onion
This can be done largely branch-free, so in a sense, you only
have a single loop, you just keep reloading and reloading until
the end. (There are at least two ways to do this reloading;
you can reload only at the top, or you can reload the entire
64-bit word and mask out the bits you just read.