The link doesn’t really explain what it is but it does have the URL of a paper (in tiny text and not as a link). If I understand correctly, this is the example code from a paper that co,pares different hash-based PRNGs for use as entropy sources on a set of GPU-based algorithms.
Exactly. On the “Common” tab you can find GLSL implementations of all the functions, which makes this page a nice reference for these kinds of hashes. And you can directly visually compare them by commenting out the right lines on the other tab.