C++语言实现系统内存分配与回收.docx

C+语言实现系统内存分配与回收#include#include#define Free 0 /空闲状态#define Busy 1 /已用状态#define OK 1 /完成#define ERROR 0 /出错#define MAX_length 640 /最大内存空间为640KBtypedef int Status;int flag;typedef struct freearea/定义一个空闲区说明表结构long size; /分区大小long address; /分区地址int state; /状态ElemType;/ 线性表的双向链表存储结构typedef struct DuLNodeElemType data;struct DuLNode *prior; /前趋指针struct DuLNode *next; /后继指针DuLNode, *DuLinkList;DuLinkList block_first; /头结点DuLinkList block_last; /尾结点Status alloc(int);/内存分配Status free(int); /内存回收Status First_fit(int);/首次适应算法Status Best_fit(int); /最佳适应算法Status Worst_fit(int); /最差适应算法void show();/查看分配Status Initblock();/开创空间表 Status Initblock()/开创带头结点的内存空间链表block_first = (DuLinkList)malloc(sizeof(DuLNode);block_last = (DuLinkList)malloc(sizeof(DuLNode);block_first-prior = NULL;block_first-next = block_last;block_last-prior = block_first;block_last-next = NULL;block_last-data.address = 0;block_last-data.size = MAX_length;block_last-data.state = Free;return OK;/分配主存Status alloc(int ch)int request = 0;cout request;if (request0 | request = 0)cout 分配大小不合适，请重试！ endl;return ERROR;if (ch = 2) /选择最佳适应算法if (Best_fit(request) = OK) cout 分配成功！ endl;else cout 内存不足，分配失败！ endl;return OK;if (ch = 3) /选择最差适应算法if (Worst_fit(request) = OK) cout 分配成功！ endl;else cout 内存不足，分配失败！ endl;return OK;else /默认首次适应算法if (First_fit(request) = OK) cout 分配成功！ endl;else cout 内存不足，分配失败！ data.size = request;temp-data.state = Busy;DuLNode *p = block_first-next;while (p)if (p-data.state = Free & p-data.size = request)/有大小恰好合适的空闲块p-data.state = Busy;return OK;break;if (p-data.state = Free & p-data.sizerequest)/有空闲块能满足需求且有剩余temp-prior = p-prior;temp-next = p;temp-data.address = p-data.address;p-prior-next = temp;p-prior = temp;p-data.address = temp-data.address + temp-data.size;p-data.size -= request;return OK;break;p = p-next;return ERROR;/最佳适应算法Status Best_fit(int request)int ch; /记录最小剩余空间DuLinkList temp = (DuLinkList)malloc(sizeof(DuLNode);temp-data.size = request;temp-data.state = Busy;DuLNode *p = block_first-next;DuLNode *q = NULL; /记录最佳插入位置while (p) /初始化最小空间和最佳位置if (p-data.state = Free & (p-data.size = request)if (q = NULL)q = p;ch = p-data.size - request;else if (q-data.size p-data.size)q = p;ch = p-data.size - request;p = p-next;if (q = NULL) return ERROR;/没有找到空闲块else if (q-data.size = request)q-data.state = Busy;return OK;elsetemp-prior = q-prior;temp-next = q;temp-data.address = q-data.address;q-prior-next = temp;q-prior = temp;q-data.address += request;q-data.size = ch;return OK;return OK;/最差适应算法Status Worst_fit(int request)int ch; /记录最大剩余空间DuLinkList temp = (DuLinkList)malloc(sizeof(DuLNode);temp-data.size = request;temp-data.state = Busy;DuLNode *p = block_first-next;DuLNode *q = NULL; /记录最佳插入位置while (p) /初始化最大空间和最佳位置if (p-data.state = Free & (p-data.size = request)if (q = NULL)q = p;ch = p-data.size - request;else if (q-data.size data.size)q = p;ch = p-data.size - request;p = p-next;if (q = NULL) return ERROR;/没有找到空闲块else if (q-data.size = request)q-data.state = Busy;return OK;elsetemp-prior = q-prior;temp-next = q;temp-data.address = q-data.address;q-prior-next = temp;q-prior = temp;q-data.address += request;q-data.size = ch;return OK;return OK;/主存回收Status free(int flag)DuLNode *p = block_first;for (int i = 0; i next;elsereturn ERROR;p-data.state = Free;if (p-prior != block_first & p-prior-data.state = Free)/与前面的空闲块相连p-prior-data.size += p-data.size;p-prior-next = p-next;p-next-prior = p-prior;p = p-prior;if (p-next != block_last & p-next-data.state = Free)/与后面的空闲块相连p-data.size += p-next-data.size;p-next-next-prior = p;p-next = p-next-next;if (p-next = block_last & p-next-data.state = Free)/与最后的空闲块相连p-data.size += p-next-data.size;p-next = NULL;return OK;/显示主存分配情况void show()int flag = 0;cout n主存分配情况:n;cout next;cout 分区号t起始地址t分区大小t状态nn;while (p)cout flag+ t;cout data.address tt;cout data.size data.state = Free) cout 空闲nn;else cout next;cout +nn;/主函数void main()int ch;/算法选择标记cout 请输入所使用的内存分配算法：n;cout ch;while (ch3)cout ch;Initblock(); /开创空间表int choice; /操