RtlULongPtrMult - NtDoc

#ifndef _NTINTSAFE_H_INCLUDED_
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES)
//
// ULONG_PTR multiplication
//
#ifdef _WIN64

#define RtlULongPtrMult    RtlULongLongMult

#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 multiplication
//
#ifdef _WIN64
// ...
#else

_Must_inspect_result_
__inline
NTSTATUS
RtlULongPtrMult(
    _In_ ULONG_PTR ulMultiplicand,
    _In_ ULONG_PTR ulMultiplier,
    _Out_ _Deref_out_range_(==, ulMultiplicand * ulMultiplier) ULONG_PTR* pulResult)
{
    ULONGLONG ull64Result = UInt32x32To64(ulMultiplicand, ulMultiplier);
    
    return RtlULongLongToULongPtr(ull64Result, pulResult);
}

#endif
#endif
#endif
View code on GitHub