Structure defining a page table (PT) entry in IA-32e paging.

pte.c

typedef struct _PTE
{
    union
    {
        struct
        {
            ULONG64 Present : 1;              // Must be 1, region invalid if 0.
            ULONG64 ReadWrite : 1;            // If 0, writes not allowed.
            ULONG64 UserSupervisor : 1;       // If 0, user-mode accesses not allowed.
            ULONG64 PageWriteThrough : 1;     // Determines the memory type used to access the memory.
            ULONG64 PageCacheDisable : 1;     // Determines the memory type used to access the memory.
            ULONG64 Accessed : 1;             // If 0, this entry has not been used for translation.
            ULONG64 Dirty : 1;                // If 0, the memory backing this page has not been written to.
            ULONG64 PageAccessType : 1;       // Determines the memory type used to access the memory.
            ULONG64 Global: 1;                // If 1 and the PGE bit of CR4 is set, translations are global.
            ULONG64 Ignored2 : 3;
            ULONG64 PageFrameNumber : 36;     // The page frame number of the backing physical page.
            ULONG64 Reserved : 4;
            ULONG64 Ignored3 : 7;
            ULONG64 ProtectionKey: 4;         // If the PKE bit of CR4 is set, determines the protection key.
            ULONG64 ExecuteDisable : 1;       // If 1, instruction fetches not allowed.
        };
        ULONG64 Value;
    };
} PTE, *PPTE;
static_assert(sizeof(PTE) == sizeof(PVOID), "Size mismatch, only 64-bit supported.");