deep-c-rsc/mudclient204-headless/ISAAC.java

public class ISAAC {

    private int count;
    private int results[];
    private int memory[];
    private int a;
    private int b;
    private int c;

    public ISAAC(int seed[]) {
        memory = new int[256];
        results = new int[256];
        for (int i = 0; i < seed.length; i++)
            results[i] = seed[i];

        init();
    }

    public int getNextValue() {
        if (count-- == 0) {
            isaac();
            count = 255;
        }
        return results[count];
    }

    private void isaac() {
        b += ++c;
        for (int i = 0; i < 256; i++) {
            int x = memory[i];
            switch (i & 3) {
                case 0: // '\0'
                    a ^= a << 13;
                    break;

                case 1: // '\001'
                    a ^= a >>> 6;
                    break;

                case 2: // '\002'
                    a ^= a << 2;
                    break;

                case 3: // '\003'
                    a ^= a >>> 16;
                    break;
            }
            a += memory[i + 128 & 0xff];
            int k;
            memory[i] = k = memory[(x & 0x3fc) >> 2] + a + b;
            results[i] = b = memory[(k >> 8 & 0x3fc) >> 2] + x;
        }

    }

    private void init() {
        int i1;
        int j1;
        int k1;
        int l1;
        int i2;
        int j2;
        int k2;
        int l = i1 = j1 = k1 = l1 = i2 = j2 = k2 = 0x9e3779b9;
        for (int i = 0; i < 4; i++) {
            l ^= i1 << 11;
            k1 += l;
            i1 += j1;
            i1 ^= j1 >>> 2;
            l1 += i1;
            j1 += k1;
            j1 ^= k1 << 8;
            i2 += j1;
            k1 += l1;
            k1 ^= l1 >>> 16;
            j2 += k1;
            l1 += i2;
            l1 ^= i2 << 10;
            k2 += l1;
            i2 += j2;
            i2 ^= j2 >>> 4;
            l += i2;
            j2 += k2;
            j2 ^= k2 << 8;
            i1 += j2;
            k2 += l;
            k2 ^= l >>> 9;
            j1 += k2;
            l += i1;
        }

        for (int j = 0; j < 256; j += 8) {
            l += results[j];
            i1 += results[j + 1];
            j1 += results[j + 2];
            k1 += results[j + 3];
            l1 += results[j + 4];
            i2 += results[j + 5];
            j2 += results[j + 6];
            k2 += results[j + 7];
            l ^= i1 << 11;
            k1 += l;
            i1 += j1;
            i1 ^= j1 >>> 2;
            l1 += i1;
            j1 += k1;
            j1 ^= k1 << 8;
            i2 += j1;
            k1 += l1;
            k1 ^= l1 >>> 16;
            j2 += k1;
            l1 += i2;
            l1 ^= i2 << 10;
            k2 += l1;
            i2 += j2;
            i2 ^= j2 >>> 4;
            l += i2;
            j2 += k2;
            j2 ^= k2 << 8;
            i1 += j2;
            k2 += l;
            k2 ^= l >>> 9;
            j1 += k2;
            l += i1;
            memory[j] = l;
            memory[j + 1] = i1;
            memory[j + 2] = j1;
            memory[j + 3] = k1;
            memory[j + 4] = l1;
            memory[j + 5] = i2;
            memory[j + 6] = j2;
            memory[j + 7] = k2;
        }

        for (int k = 0; k < 256; k += 8) {
            l += memory[k];
            i1 += memory[k + 1];
            j1 += memory[k + 2];
            k1 += memory[k + 3];
            l1 += memory[k + 4];
            i2 += memory[k + 5];
            j2 += memory[k + 6];
            k2 += memory[k + 7];
            l ^= i1 << 11;
            k1 += l;
            i1 += j1;
            i1 ^= j1 >>> 2;
            l1 += i1;
            j1 += k1;
            j1 ^= k1 << 8;
            i2 += j1;
            k1 += l1;
            k1 ^= l1 >>> 16;
            j2 += k1;
            l1 += i2;
            l1 ^= i2 << 10;
            k2 += l1;
            i2 += j2;
            i2 ^= j2 >>> 4;
            l += i2;
            j2 += k2;
            j2 ^= k2 << 8;
            i1 += j2;
            k2 += l;
            k2 ^= l >>> 9;
            j1 += k2;
            l += i1;
            memory[k] = l;
            memory[k + 1] = i1;
            memory[k + 2] = j1;
            memory[k + 3] = k1;
            memory[k + 4] = l1;
            memory[k + 5] = i2;
            memory[k + 6] = j2;
            memory[k + 7] = k2;
        }

        isaac();
        count = 256;
    }
}