RtlULongPtrToUInt - NtDoc

#ifndef _NTINTSAFE_H_INCLUDED_
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES)
//
// ULONG_PTR -> UINT conversion
//
#ifdef _WIN64

#define RtlULongPtrToUInt  RtlULongLongToUInt

#endif
#endif
#endif
View code on GitHub

#ifndef _NTINTSAFE_H_INCLUDED_
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES)
//
// ULONG_PTR -> UINT conversion
//
#ifdef _WIN64
// ...
#else

_Must_inspect_result_
__inline
NTSTATUS
RtlULongPtrToUInt(
    _In_ ULONG_PTR ulOperand,
    _Out_ _Deref_out_range_(==, ulOperand) UINT* puResult)
{
    C_ASSERT(sizeof(ULONG_PTR) == sizeof(UINT));
    *puResult = (UINT)ulOperand;    
    return STATUS_SUCCESS;
}

#endif
#endif
#endif
View code on GitHub