The GNU C Library, known as glibc, is a free and open source version of the C standard library. If you've used open source software, then you've probably used a program built using this library.

Among the many other tools provided by this library is a Linear Congruential Generator. This generator uses bit masking to return only the last 31 bits of the Seed.

// This code is adapted from the source code
// of GLIBC found here:
//
// https://sourceware.org/git/glibc.git

// The current state value
state = 1138;

// Our constants
a = 1103515245;
c = 12345;

// random number generator
function RandomNumber() {

	// Run the function
	state = ((a * state) + c) AND $7FFFFFFF;

	// Return the new value
	return state;

}