gistfile1.java

public class BitCollissionDetector {

    private final int[] cdi_map;
	
    public BitCollissionDetector(final int[] cm ) {
	this.cdi_map = cm;
    }

    public boolean test(final int x, final int y ) {
	final int column_bit_mask = 1<<(x>>5); //get proper constant, configurable?
	final int row = y>>5;
	return (this.cdi_map[row]&column_bit_mask) == column_bit_mask;
    }

}