code: public void setNull(long[] mask) {
  		for (int maskPos = 0, i = 0; i < this.numFields;) {
  			long currMask = mask[maskPos];
  			for (int k = 64; i < this.numFields && k > 0; --k, i++, currMask >>>= 1) {
  				if ((currMask & 0x1) != 0) {
  					internallySetField(i, null);
  				}
  			}
  		}
  	}
docs: Sets the fields to <code>null</code> using the given bit mask.
  The bits correspond to the individual columns: <code>(1 == nullify, 0 == keep)</code>.
  
  @param mask Bit mask, where the i-th least significant bit in the n-th bit mask represents the
  <code>(n*64) + i</code>-th field in the record.