操作系统实验_动态分区存储管理方式的主存分配回收.doc

?操作系统实验_动态分区存储管理方式的主存分配回收 ////////////////////////////////////////////////////////////// 功能://?? 《计算机操作系统》实验//?? 首次适应性算法//?? 摸拟 动态分区 存储管理方式的主存 分配 和 回收// 时间://?? 2005-11-14//////////////////////////////////////////////////////////// ? #include iostream.h#include iomanip.h #define ERR_NOFREEAREA 1#define ERR_NOADEQUACYAREA 2#define ERR_ALLOCATED 4 #define ERR_NOJOBS 1#define ERR_NOSUCHJOB 2#define ERR_RECLAIMED 4 typedef struct tagUsedNode{?long address;?long length;?int flag;?//作业名?struct tagUsedNode *next;} USED_AREA , *USED_TABLE; typedef struct tagFreeNode{?long address;?long length;?struct tagFreeNode *next;} FREE_AREA , *FREE_TABLE; //空闲区、作业区链表USED_TABLE usedTable = NULL;FREE_TABLE freeTable = NULL; //给作业分配空间//jobname: 作业名//jobsize: 作业所需空间大小int Allocate( int jobname , long jobsize ){?//如果没有空闲区?if( freeTable == NULL )??return ERR_NOFREEAREA;?FREE_TABLE p = freeTable;?FREE_TABLE q = p;?//找首次适应空闲区?while( p != NULL p-length jobsize )?{??q = p;??p = p-next;?}?//如果找不到有足够空间的分区?if( p == NULL )??return ERR_NOADEQUACYAREA; ?USED_TABLE x = new USED_AREA;?x-address = p-address;?x-length = jobsize;?x-flag = jobname;?x-next = NULL; ?//如果该分区大于作业需求，空间大小减去作业大小?if( p-length jobsize )?{??p-length -= jobsize;??p-address += jobsize;?}?//如果该分区等于作业大小，删除该分区?else?{??if( p == freeTable )???freeTable = NULL;??else???q-next = p-next;??delete p;?}?//作业加入“作业表”中?USED_TABLE r = usedTable;?USED_TABLE t = r; ?while( r != NULL r-address x-address )?{??t = r;??r = r-next;?}??if( usedTable == NULL )??usedTable = x;?else?{??x-next = r;??t-next = x;?} ?return ERR_ALLOCATED;} //回收作业空间//jobname: 作业名int Reclaim( int jobname ){?if( usedTable == NULL )??return ERR_NOJOBS;?USED_TABLE p = usedTable;?USED_TABLE q = p;?while( p != NULL p-flag != jobname )?{??q = p;??p = p-next;?}?//如果没有该作业?if( p == NULL )??return ERR_NOSUCHJOB;?//回收后的空间加入到空闲区?FREE_TABLE r = freeTable;?FREE_TABLE t = r;?FREE_TABLE x;?whil