optimized small key hashes by using bzhi instead of the switch construct

[octanico]

No description provided.

[sebres]

Endianness?

One could surely do that, but have to check __BYTE_ORDER (__BIG_ENDIAN__, __LITTLE_ENDIAN__, etc) or use htonll and co.
Just... good luck to implement it cross platform and compiler - for instance some compilers may lack __BYTE_ORDER and friends as well as probably unable to optimize constructs like this at compile time:

int n = 1; if(*(char *)&n) { /* Little Endian */ } else { /* Big Endian */ }