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虚拟内存的按需调拨

windows C++ 虚拟内存的按需调拨

虚拟内存的按需调拨

/*------------------------------------------------------------------------24-SEHAndMemory.cpp演示虚拟内存的按需调拨-----------------------------------------------------------------------*/
#include <windows.h>
#include <tchar.h>
#include <locale.h>#define PAGELIMIT 80
LPBYTE lpNxtPage;
DWORD dwPages = 0;
DWORD dwPageSize;//页面大小,一般为4KBINT PageFualtExceptionFilter(DWORD dwCode) {LPVOID lpvResult;//不是非法访问内存if (dwCode != EXCEPTION_ACCESS_VIOLATION) {//线程试图读写一个虚拟内存地址，但在这个地址它并不具备相应权限return EXCEPTION_EXECUTE_HANDLER;//执行except块的异常处理程序代码}//当超过指定的页面数时if (dwPages >= PAGELIMIT) {return EXCEPTION_EXECUTE_HANDLER;//执行except块的异常处理程序代码}//非法访问内存，则为预订的空间提交下一页物理存储器lpvResult = VirtualAlloc((LPVOID)lpNxtPage, dwPageSize, MEM_COMMIT, PAGE_READWRITE);if (lpvResult == NULL) {return EXCEPTION_EXECUTE_HANDLER;//执行except块的异常处理程序代码}//提交成功dwPages++;lpNxtPage += dwPageSize;_tprintf(_T("第%d页提交成功！\n"), dwPages);return EXCEPTION_CONTINUE_EXECUTION; //重新执行触发异常的那条CPU指令
}int main() {_tsetlocale(LC_ALL, _T("chs"));LPVOID lpvBase; LPTSTR lpPtr; BOOL bSuccess;SYSTEM_INFO sSysInfo;GetSystemInfo(&sSysInfo);dwPageSize = sSysInfo.dwPageSize;_tprintf(_T("CPU页面大小为%dKB.\n"), sSysInfo.dwPageSize / 1024);//预订存储器lpvBase = VirtualAlloc(NULL, PAGELIMIT*dwPageSize, MEM_RESERVE, PAGE_NOACCESS);lpPtr = (LPTSTR)(lpNxtPage = (LPBYTE)lpvBase);for (DWORD i = 0; i < PAGELIMIT*dwPageSize / sizeof(TCHAR); i++) {__try {lpPtr[i] = _T('a');//写入一个字节的数据}__except (PageFualtExceptionFilter(GetExceptionCode())) {_tprintf(_T("异常被处理\n"));//ExitProcess(GetLastError());}}bSuccess = VirtualFree(lpvBase, 0, MEM_RELEASE);_tprintf(_T("释放操作%s.\n"), bSuccess ? _T("成功") : _T("失败"));_tsystem(_T("PAUSE"));return 0;
}