procedure sort( var r : ArrayToSort; lo, up : integer );

     var  i, j : integer;
          tempr : ArrayEntry;
     begin
     while up>lo do begin
          i := lo;
          j := up;
          tempr := r[lo];
          {*** Split file in two ***}
          while i<j do begin
               while r[j].k > tempr.k do
                    j := j-1;
               r[i] := r[j];
               while (i<j) and (r[i].k<=tempr.k) do
                    i := i+1;
               r[j] := r[i]
               end;
          r[i] := tempr;
          {*** Sort recursively, the smallest first ***}
          if i-lo < up-i then begin
                    sort(r,lo,i-1);
                    lo := i+1
                    end
               else begin
                    sort(r,i+1,up);
                    up := i-1
                    end
          end
     end;