Test.java

import java.util.Random;

public final class Test {

    public static long getKey(final int x, final int y, final int z) {
        return ((long)x & 0x7FFFFFF) | (((long)z & 0x7FFFFFF) << 27) | ((long)y << 54);
    }
    
    public static int getX(final long key) {
        return (int) ((key << 37) >> 37);
    }
    
    public static int getY(final long key) {
        return (int) (key >>> 54);
    }
    
    public static int getZ(final long key) {
        return  (int) ((key << 10) >> 37);
    }
    
    public static void test(final int x, final int y, final int z) {
        final long key = getKey(x, y, z);
        
        final int decx = getX(key);
        final int decy = getY(key);
        final int decz = getZ(key);
        
        if (decx != x || decy != y || decz != z) {
            throw new RuntimeException("Encoding error for coordinates (" + x + "," + y + "," + z + "): " +
                    "Encoded value: " + Long.toHexString(key) + ", decoded coordinates: (" + decx + "," + decy + "," + decz + ")");
        }
        
    }
    

    public static void main(final String[] args) {
        final Random random = new Random(0x4C4541463E414C4CL);
        
        for (long i = 0; i < 100_000_000; ++i) {
            final int x = random.nextInt(67_108_864*2) - 67_108_864;
            final int y = random.nextInt(1024);
            final int z = random.nextInt(67_108_864*2) - 67_108_864;
            test(x, y, z);
        }
        
        
        test(0, 0, 0);
        test(30_000_000, 0, 30_000_000);
        test(-30_000_000, 0, -30_000_000);
        test(-30_000_000, 0, 0);
        test(0, 0, -30_000_000);
        test(-1, 255, -1);
        test(-30_000_000, 255, -30_000_000);
        test(30_000_000, 255, 30_000_000);
        
        test(-67_108_864, 1023, -67_108_864);
        test(67_108_863, 1023, 67_108_863);
        
        
        System.out.println("Passed without incident");
    }

}