RtlLongPtrToInt - NtDoc

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

#define RtlLongPtrToInt    RtlLongLongToInt

#endif
#endif
#endif
View code on GitHub

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

_Must_inspect_result_
__inline
NTSTATUS
RtlLongPtrToInt(
    _In_ LONG_PTR lOperand,
    _Out_ _Deref_out_range_(==, lOperand) INT* piResult)
{
    C_ASSERT(sizeof(INT) == sizeof(LONG_PTR));
    *piResult = (INT)lOperand;
    return STATUS_SUCCESS;
}   

#endif
#endif
#endif
View code on GitHub