Java - Simbolos &= ~

Que tal alguien me podria explicar que significan estas cosas?
((x + dx[d]) << 16)
maze[x + dx[d]][y + dy[d]] &= ~16;
x = todo[n] >> 16;
y = todo[n] & 65535;
maze[x][y] &= ~48;

les pongo todo el código para que lo vean . . . gracias (es un generador de laberintos)

import java.awt.*;
import java.applet.*;

public class Maze extends Applet {
int maze[][];

public void init () {
int x, y, n, d;
int dx[] = { 0, 0, -1, 1 };
int dy[] = { -1, 1, 0, 0 };
int todo[] = new int[400], todonum = 0;

/* We want to create a maze on a grid. */
maze = new int[20][20];

/* We start with a grid full of walls. */
for (x = 0; x < 20; ++x)
for (y = 0; y < 20; ++y)
if (x == 0 || x == 19 || y == 0 || y == 19) {
maze[x][y] = 32;
} else {
maze[x][y] = 63;
}

/* Select any square of the grid, to start with. */
x = (int) (1 + Math.random () * 18);
y = (int) (1 + Math.random () * 18);

/* Mark this square as connected to the maze. */
maze[x][y] &= ~48;

/* Remember the surrounding squares, as we will */
for (d = 0; d < 4; ++d)
if ((maze[x + dx[d]][y + dy[d]] & 16) != 0) {
/* want to connect them to the maze. */
todo[todonum++] = ((x + dx[d]) << 16) | (y + dy[d]);
maze[x + dx[d]][y + dy[d]] &= ~16;
}

/* We won't be finished until all is connected. */
while (todonum > 0) {
/* We select one of the squares next to the maze. */
n = (int) (Math.random () * todonum);
x = todo[n] >> 16;
y = todo[n] & 65535;

/* We will connect it, so remove it from the queue. */
todo[n] = todo[--todonum];

/* Select a direction, which leads to the maze. */
do
d = (int) (Math.random () * 4);
while ((maze[x + dx[d]][y + dy[d]] & 32) != 0);

/* Connect this square to the maze. */
maze[x][y] &= ~((1 << d) | 32);
maze[x + dx[d]][y + dy[d]] &= ~(1 << (d ^ 1));

/* Remember the surrounding squares, which aren't */
for (d = 0; d < 4; ++d)
if ((maze[x + dx[d]][y + dy[d]] & 16) != 0) {

/* connected to the maze, and aren't yet queued to be. */
todo[todonum++] = ((x + dx[d]) << 16) | (y + dy[d]);
maze[x + dx[d]][y + dy[d]] &= ~16;
}
/* Repeat until finished. */
}

/* One may want to add an entrance and exit. */
maze[1][1] &= ~1;
maze[18][18] &= ~2;
}

public void paint (Graphics g) {
int x, y;

for (x = 1; x < 19; ++x)
for (y = 1; y < 19; ++y) {
if ((maze[x][y] & 1) != 0)
g.drawLine (x * 10, y * 10, x * 10 + 10, y * 10);
if ((maze[x][y] & 2) != 0)
g.drawLine (x * 10, y * 10 + 10, x * 10 + 10, y * 10 + 10);
if ((maze[x][y] & 4) != 0)
g.drawLine (x * 10, y * 10, x * 10, y * 10 + 10);
if ((maze[x][y] & 8) != 0)
g.drawLine (x * 10 + 10, y * 10, x * 10 + 10, y * 10 + 10);
}
}
}