RtlULongLongAdd - NtDoc

#ifndef _NTINTSAFE_H_INCLUDED_
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES)

//
// ULONGLONG addition
//
_Must_inspect_result_
__inline
NTSTATUS
RtlULongLongAdd(
    _In_ ULONGLONG ullAugend,
    _In_ ULONGLONG ullAddend,
    _Out_ _Deref_out_range_(==, ullAugend + ullAddend) ULONGLONG* pullResult)
{
    NTSTATUS status;

    if ((ullAugend + ullAddend) >= ullAugend)
    {
        *pullResult = (ullAugend + ullAddend);
        status = STATUS_SUCCESS;
    }
    else
    {
        *pullResult = ULONGLONG_ERROR;
        status = STATUS_INTEGER_OVERFLOW;
    }
    
    return status;
}

#endif
#endif
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