This is a translation of the [official reference implementation][1] with
few other changes. The bad news is that the reference implementation is
designed for simplicity and not speed, so there's a lot of room for
performance improvement. The good news is that, according to the crypto
benchmark, the implementation is still fast relative to the other
hashing algorithms:
```
md5: 430 MiB/s
sha1: 386 MiB/s
sha256: 191 MiB/s
sha512: 275 MiB/s
sha3-256: 233 MiB/s
sha3-512: 137 MiB/s
blake2s: 464 MiB/s
blake2b: 526 MiB/s
blake3: 576 MiB/s
poly1305: 1479 MiB/s
hmac-md5: 653 MiB/s
hmac-sha1: 553 MiB/s
hmac-sha256: 222 MiB/s
x25519: 8685 exchanges/s
```
[1]: https://github.com/BLAKE3-team/BLAKE3