def countContigClusters(clus)
      cur = clus; nxt = 0
      loop do
        nxt = getFatEntry(cur)
        break if nxt != cur + 1
        cur = nxt; redo
      end
      raise "Damaged cluster in cluster chain" if nxt == CC_DAMAGED
      cur - clus + 1
    end
def countContigClusters(clus)
      cur = clus; nxt = 0
      loop do
        nxt = getFatEntry(cur)
        break if nxt != cur + 1
        cur = nxt; redo
      end
      raise "Damaged cluster in cluster chain" if nxt == CC_DAMAGED
      cur - clus + 1
    end
Count the number of continuous clusters from some beginning cluster.