Java RNG

public class JavaRandom {
        private static ulong Mask = (1UL << 48) - 1UL;
        private static ulong Multiplier = 0x5DEECE66DUL;
        private static ulong AddEnd = 0xBUL;
        private static ulong Seed = 0UL;

        public JavaRandom(ulong seed) {
            SetSeed(seed);
        }

        public void SetSeed(ulong seed) {
            Seed = (seed ^ Multiplier) & Mask;
        }

        public int Next(int bits) {
            ulong oldseed, nextseed;
            do {
                oldseed = Seed;
                nextseed = (oldseed * Multiplier + AddEnd) & Mask;

                if (Seed == oldseed) {
                    Seed = nextseed;
                    break;
                }
            } while (true);

            return (int)(nextseed >> (48 - bits));
        }

        public int NextInt(int max) {
            if ((max & -max) == max)
                return (int)((max * (long)Next(31)) >> 31);

            int bits, val;
            do {
                bits = Next(31);
                val = bits % (int)max;
            } while (bits - val + (max - 1) < 0);
            return val;
        }

        public long NextLong() {
            return ((long)Next(32) << 32) + Next(32);
        }
    }