CityHash provides hash functions for strings.  The functions mix the
input bits thoroughly but are not suitable for cryptography.  See
"Hash Quality," below, for details on how CityHash was tested and so on.

Functions by CityHash:

- CityHash32() returns a 32-bit hash.
- CityHash64() and similar return a 64-bit hash.
- CityHash128() and similar return a 128-bit hash and are tuned for
strings of at least a few hundred bytes.  Depending on your compiler
and hardware, it's likely faster than CityHash64() on sufficiently long
strings.  It's slower than necessary on shorter strings, but we expect
that case to be relatively unimportant.
- CityHashCrc128() and similar are variants of CityHash128() that depend
on _mm_crc32_u64(), an intrinsic that compiles to a CRC32 instruction
on some CPUs.  However, none of the functions we provide are CRCs.
- CityHashCrc256() is a variant of CityHashCrc128() that also depends
on _mm_crc32_u64().  It returns a 256-bit hash.

All members of the CityHash family were designed with heavy reliance
on previous work by Austin Appleby, Bob Jenkins, and others.
For example, CityHash32 has many similarities with Murmur3a.