untwist is a collection of PRNG's from .NET, Free Pascal, Turbo Pascal, Python.

Python and Free Pascal use the Mersenne Twister as a randomization source. Turbo Pascal and Java are using a linear congruential generator (LCG). .NET is using a modified version of Donald E. Knuth's subtractive random number generator algorithm.

Given the same input (seed) they generate the same values as the ones in the respective languages.

Also, besides their normal use, I have added functions to go backward. The Mersenne Twister and LCG's are reversible. Also, LCG's and subtractive generators are trivial to revert.

I got the idea of reversing the generators from several places, after I had to break the seed of some generator, in order to reduce the size of the archived dataset.

There are some cases in which the reverse does not work as expected. Try not to mix next and prev versions of the methods as you might run into strange situations. Some of the situations are captured by unit tests which are currently marked as ignored. Most of the time things go well.

Nevertheless, use it at your own risk. This library comes with no guarantees.

<dependency>
    <groupId>ro.derbederos</groupId>
    <artifactId>untwist</artifactId>
    <version>0.5</version>
</dependency>

compile 'ro.derbederos:untwist:0.5'

Enjoy using them!