Function RtlUpcaseUnicodeToOemN 

pub unsafe extern "system" fn RtlUpcaseUnicodeToOemN(
    OemString: PCHAR,
    MaxBytesInOemString: ULONG,
    BytesInOemString: PULONG,
    UnicodeString: PCWCH,
    BytesInUnicodeString: ULONG,
) -> NTSTATUS