Trying to implement xorshift with deplorable results (PRNG)

Since i'm more of a unityscript guy, I'm having trouble since I only find the raw code for C/C++ versions of xorshift128, which actually provides no documentation as to what the variables mean.

Since from what i've read xorshift128 is what unity random.seed uses (but I don't want to use in case they change the implementation of random.seed and random.value), i'm trying to find a C# code to make what unity is doing with random.range, given a seed

The C# version I found doesn't work (gives me error and I really don't know why nor I can spend the time right now to make my brain understand the C# syntax as of now)

Thanks in advance