主存回收函数实现：有上邻空闲区和下邻空闲区，它们与回收区的合并；有上邻空闲区，无下邻空闲区，回收区与上邻空闲区的合并；无上邻空闲区，有下邻空闲区，回收区与下邻空闲区的合并。-Main memory to achieve recovery of function: there are o-free zones and free zones under the neighborhood, which combined with the recovery area have on adjacent