code: @Override
      protected int msd(Integer a, Integer b) {
          /*
           * Value equal
           */
          if (a.intValue() == b.intValue()) {
              return -1;
          }
          /*
           * This is a fast way to compute floor(log_2(a xor b)).
           */
          float axorb = a ^ b;
          return Math.getExponent(axorb);
      }
docs: {@inheritDoc}