bithacks.h - bit hacks header file - good coders code, great reuse
http://www.catonmat.net/blog/bit-hacks-header-file/

This header file is called “bithacks.h” and it contains various macros for bit manipulations. I also wrote tests for all the macros in the “bithacks-test.c” program. The most beautiful part of “bithacks.h” is the “B8” macro that allows to write something like ” x = B8(10101010) ” and turns it into ” x = 170 ” (because 10101010 in binary is 170 in decimal). I have not yet added B16 and B32 macros but I will add them when I publish the article on advanced bithacks. The credit for the B8 idea goes to Tom Torfs who was the first to write it.