http://www.hackersdelight.org/
http://www.inwap.com/pdp10/hbaker/hakmem/hakmem.html
(We recently had to grab the C standards in order to bust out some integer under/overflow macros that wouldn't be brittle.)
And my faviourite bit hack question on SO: https://stackoverflow.com/questions/14537831/isolate-specifi...
I would guess one of the reasons it's here though is that it's almost required reading for Google interviews, #DetermineIfPowerOf2 is a particular favorite.
http://aggregate.org/MAGIC/
https://hn.algolia.com/?q=bit+twiddling+hacks#!/story/foreve...
We put 2005 on it, though the Internet Archive says there were earlier versions.
http://www.hackersdelight.org/
http://www.inwap.com/pdp10/hbaker/hakmem/hakmem.html
(We recently had to grab the C standards in order to bust out some integer under/overflow macros that wouldn't be brittle.)