RtlIntPtrToInt - NtDoc

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

#define RtlIntPtrToInt 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)
//
// INT_PTR -> INT conversion
//
#ifdef _WIN64
// ...
#else

_Must_inspect_result_
__inline
NTSTATUS
RtlIntPtrToInt(
    _In_ INT_PTR iOperand,
    _Out_ _Deref_out_range_(==, iOperand) INT* piResult)
{
    *piResult = (INT)iOperand;
    return STATUS_SUCCESS;
}

#endif
#endif
#endif
View code on GitHub