C++ 内存映射

HANDLE hFile = NULL;HANDLE hFileMap = NULL;const viewmapsize = 8 * 1024 * 1024;//8mDWORD highsize,lowsize,fileoffsetlow,fileoffsethigh,mapsize;_int64 filesize,offset,remain;int dwError;do {//打开文件hFile= CreateFile("g:\\1289527402.png",GENERIC_READ,FILE_SHARE_READ|FILE_SHARE_WRITE,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL);if ( hFile == INVALID_HANDLE_VALUE ){CString cs;cs.Format("打开文件失败:%d",GetLastError());AfxMessageBox(cs);break;}lowsize = GetFileSize(hFile,&highsize);if ( lowsize == 0xFFFFFFFF && ( dwError = GetLastError() ) != NO_ERROR ){CString cs;cs.Format("获取文件大小失败:%d",dwError);AfxMessageBox(cs);break;}//文件大小filesize = highsize<<32 lowsize="" hfilemap="CreateFileMapping(hFile,NULL," page_readonly="" highsize="" lowsize="" null="" if="" hfilemap="=" null="" cstring="" cs="" cs="" format="" createfilemapping="" :="" d="" getlasterror="" afxmessagebox="" cs="" break="" offset="0;" mapsize="(int)(filesize"> viewmapsize ? viewmapsize : filesize);fileoffsethigh = (int)(offset >> 32);fileoffsetlow = (int)(offset / viewmapsize * viewmapsize);LPVOID lpmap;while ( filesize > offset && ( lpmap = MapViewOfFile(hFileMap,FILE_MAP_READ,fileoffsethigh,fileoffsetlow,mapsize) ) != NULL ){offset += mapsize;remain = filesize - offset;mapsize = (int)(remain > viewmapsize ? viewmapsize : remain);fileoffsethigh = (int)(offset >> 32);fileoffsetlow = (int)(offset);UnmapViewOfFile(lpmap);}if ( lpmap == NULL ){CString cs;cs.Format("建立MapViewOfFile失败:%d",GetLastError());AfxMessageBox(cs);break;}elseUnmapViewOfFile(lpmap);if ( filesize == offset )AfxMessageBox("映射文件结束");}while (0);if ( hFileMap )CloseHandle(hFileMap);if (hFile)CloseHandle(hFile);