implementation of rand()

Question

I am writing some embedded code in C and need to use the rand() function. Unfortunately, rand() is not supported in the library for the controller. I need a simple implement

Answer 1

I found this: Simple Random Number Generation, by John D. Cook.

It should be easy to adapt to C, given that it's only a few lines of code.

Edit: and you could clarify what you mean by "relatively high-quality". Are you generating encryption keys for nuclear launch codes, or random numbers for a game of poker?