code: private static int nextPowerOfTwo(int v) {
          assert v >= 0;
          v--;
          v |= v >> 1;
          v |= v >> 2;
          v |= v >> 4;
          v |= v >> 8;
          v |= v >> 16;
          v++;
          return v;
      }
docs: taken from http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2