链表法页框的分配和去配

采用链表的方法模拟分页式存储空间的分配和去配 

MemManager.h

#pragma once #define MAX_MEM_LEN 512 class CMemManager { private: struct MemItem { struct MemItem* prior; struct MemItem* next; bool bFree; int nPos; int nLen; int nOwner; MemItem(MemItem* pri, MemItem* nxt, bool bfree, int nPosition, int nLength) { prior = pri; next = nxt; bFree = bfree; nPos = nPosition; nLen = nLength; nOwner = -1; } }; public: CMemManager(void); ~CMemManager(void); private: const static int m_csnMemBlock = MAX_MEM_LEN; int m_MemBlocks[MAX_MEM_LEN]; MemItem* m_pBase; public: void* GetMem(int nSize, int nOwner); void FreeMem(void* p); void Show(void); };

MemManager.cpp

#include <iostream> #include "MemManager.h" using namespace std; CMemManager::CMemManager(void) { m_pBase = new MemItem(0, 0, true, 0, m_csnMemBlock); } CMemManager::~CMemManager(void) { delete m_pBase; m_pBase = 0; } void* CMemManager::GetMem(int nSize, int nOwner) { MemItem* p = 0; for (MemItem* pTemp = m_pBase; pTemp; pTemp = pTemp->next) { if (pTemp->bFree && pTemp->nLen >= nSize) { int nLeft = pTemp->nLen - nSize; if (0 == nLeft) { pTemp->bFree = false; p = pTemp; } else { p = new MemItem(pTemp, pTemp->next, true, pTemp->nPos+nSize, nLeft); if (!p) { break; } if (pTemp->next) { pTemp->next->prior = p; } pTemp->next = p; pTemp->bFree = false; pTemp->nLen = nSize; p = pTemp; } p->nOwner = nOwner; break; } } return p; // fail } void CMemManager::FreeMem(void* p) { MemItem* pItem = static_cast<MemItem*>(p); pItem->bFree = true; bool bDelete = false; if (pItem->next && pItem->next->bFree) { MemItem* pTemp = pItem->next; pItem->next = pTemp->next; if (pTemp->next) { pTemp->next->prior = pItem; } pItem->nLen += pTemp->nLen; delete pTemp; } if (pItem->prior && pItem->prior->bFree) { pItem->prior->next = pItem->next; if (pItem->next) { pItem->next->prior = pItem->prior; } pItem->prior->nLen += pItem->nLen; delete pItem; } } void CMemManager::Show(void) { cout << endl << "------------------------------------" << endl; for (MemItem* p = m_pBase; p; p = p->next) { cout << "Free: " << (p->bFree ? "true " : "false") << " "; if (!p->bFree) { cout << "Owner: " << p->nOwner << " "; } cout << "Pos: " << p->nPos << " " << "Length: " << p->nLen << endl; } }

测试代码

#include <iostream> #include <ctime> #include "MemManager.h" using namespace std; CMemManager g_mem; int main() { int a; void* pArray[10] = {0}; srand((unsigned int)time(0)); while (cin >> a) { int i = rand() % 10; cout << "i = " << i; if (pArray[i]) { g_mem.FreeMem(pArray[i]); pArray[i] = 0; } else { int nLen = rand() % 128; cout << " nLen = " << nLen; pArray[i] = g_mem.GetMem(nLen, i); } g_mem.Show(); } return 0; }