Mersenne twister (Java)

From LiteratePrograms
Jump to: navigation, search
Other implementations: C | Java

This program is a code dump.
Code dumps are articles with little or no documentation or rearrangement of code. Please help to turn it into a literate program. Also make sure that the source of this code does consent to release it under the CC0 license.


This program implements the Mersenne twister algorithm for generation of pseudorandom numbers. The original code was written by Michael Brundage and has been placed in the public domain. [1]

<<MT.java>>=
public final class MT {
    private int mt_index;
    private int[] mt_buffer = new int[624];

    public MT() {
        java.util.Random r = new java.util.Random();
        for (int i = 0; i < 624; i++)
            mt_buffer[i] = r.nextInt();
        mt_index = 0;
    }

    public int random() {
        if (mt_index == 624)
        {
            mt_index = 0;
            int i = 0;
            int s;
            for (; i < 624 - 397; i++) {
                s = (mt_buffer[i] & 0x80000000) | (mt_buffer[i+1] & 0x7FFFFFFF);
                mt_buffer[i] = mt_buffer[i + 397] ^ (s >> 1) ^ ((s & 1) * 0x9908B0DF);
            }
            for (; i < 623; i++) {
                s = (mt_buffer[i] & 0x80000000) | (mt_buffer[i+1] & 0x7FFFFFFF);
                mt_buffer[i] = mt_buffer[i - (624 - 397)] ^ (s >> 1) ^ ((s & 1) * 0x9908B0DF);
            }
        
            s = (mt_buffer[623] & 0x80000000) | (mt_buffer[0] & 0x7FFFFFFF);
            mt_buffer[623] = mt_buffer[396] ^ (s >> 1) ^ ((s & 1) * 0x9908B0DF);
        }
        return mt_buffer[mt_index++];
    }
}
Download code
hijacker
hijacker
hijacker
hijacker