Spiff

#define BITCOUNT(x) (((BX_(x)+(BX_(x)>>4)) & 0x0F0F0F0F) % 255)
#define BX_(x) ((x) - (((x)>>1)&0x77777777) \
- (((x)>>2)&0x33333333) \
- (((x)>>3)&0x11111111))

-- really weird C code to count the number of bits in a word
--

Around computers it is difficult to find the correct unit of time to measure progress. Some cathedrals took a century to complete.
Can you imagine the grandeur and scope of a program that would take as long?
-- Epigrams in Programming, ACM SIGPLAN Sept. 1982