CountBitsSet

I was curious how much better the Algorithms, pointed out by BitTwiddling Hacks, perform than a simple Lookup Table approach...
Now I think, perhaps my little investigation is interesting for others too...

PS: the parallel counting Algo is about 35% faster on average on my computers than a simple LUT based solution. Also this shows nicely how different a human brain compatible solution is to a binary machine optimal solution :-)

In the meantime I added other Algorithms beside countbisset (hamming weight): ceil(log2()) + floor(log2()), bitreverse, ...

I also recommand to try the code with different compilers and / or plattforms.

PS: see result.txt in Code, to see various runs with different compilers and compiler switches