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've made a collection of random number generators, "simplerandom", that are compact and suitable for embedded systems. The collection is available in C and Python.

I've looked around for a bunch of simple and decent ones I could find, and put them together in a small package. They include several Marsaglia generators (KISS, MWC, SHR3), and a couple of L'Ecuyer LFSR ones.

All the generators return an unsigned 32-bit integer, and typically have a state made of 1 to 4 32-bit unsigned integers.

Interestingly, I found a few issues with the Marsaglia generators, and I've tried to fix/improve all those issues. Those issues were:

• SHR3 generator (component of Marsaglia's 1999 KISS generator) was broken.
• MWC low 16 bits have only an approx 2^29.1 period. So I made a slightly improved MWC, which gives the low 16 bits a 2^59.3 period, which is the overall period of this generator.

I uncovered a few issues with seeding, and tried to make robust seeding (initialisation) procedures, so they won't break if you give them a "bad" seed value.