Fast Bit Counting

description:: > From: W.Baden (wilbaden@netcom.com) > Subject: Re: Counting bits... > Newsgroups: comp.lang.forth > Date: 1995-02-26 06:12:45 PST : count-bits ( number -- bits ) [ HEX ] DUP 55555555 AND SWAP 1 RSHIFT 55555555 AND + DUP 33333333 AND SWAP 2 RSHIFT 33333333 AND + DUP 0F0F0F0F AND SWAP 4 RSHIFT 0F0F0F0F AND + [ DECIMAL ] 255 MOD ; > From: Michael Pr"umm (mip@wa.oche.de) > Subject: Re: bit counting algorithm > Newsgroups: comp.lang.forth > Date: 1994-07-28 00:54:03 PST > > And here is another one: octal > : ones ( uint32 - numbits) dup 1 RSHIFT 33333333333 and dup 1 RSHIFT 33333333333 and + - dup 3 RSHIFT + 30707070707 and 77 mod ;