typedef struct _MAPPED_FILE_SEGMENT
{
    CONTROL_AREA *ControlArea;
    unsigned long TotalNumberOfPtes;
    SEGMENT_FLAGS SegmentFlags;
    unsigned __int64 NumberOfCommittedPages;
    unsigned __int64 SizeOfSegment;
    union
    {
        MMEXTEND_INFO *ExtendInfo;
        void *BasedAddress;
    };
    EX_PUSH_LOCK SegmentLock;
} MAPPED_FILE_SEGMENT, *PMAPPED_FILE_SEGMENT;