xxHash is an extremely fast non-cryptographic hash algorithm, working at speeds close to RAM limits. It is proposed in two flavors, 32 and 64 bits.
TODO merge into xxhash-d TODO make endian-aware
Compute xxHash-64 of input string data, with optional seed seed.
Compute xxHash-64 of input data, with optional seed seed.
xxHash-64, based on Yann Collet's descriptions