[wavemode]

I mean, you've linked to a function performing md5 hashing. That's pretty much exactly what I would expect such code to look like.

Case in point: https://github.com/postgres/postgres/blob/master/src/common/...

[f311a]

It's not idiomatic implementation in Rust, just translation from C. A few Rust macros simplify implementation and cut the code in half.