code: private static void vswap(int[] fmap, int p1, int p2, int n) {
          n += p1;
          while (p1 < n) {
              int t = fmap[p1];
              fmap[p1++] = fmap[p2];
              fmap[p2++] = t;
          }
      }
docs: /*--
  LBZ2: The following is an implementation of
  an elegant 3-way quicksort for strings,
  described in a paper "Fast Algorithms for
  Sorting and Searching Strings", by Robert
  Sedgewick and Jon L. Bentley.
  --