Function read_raw_data_zerocopy 

pub fn read_raw_data_zerocopy<'a>(
    file_data: &'a [u8],
    layout: &DataLayout,
    dataspace: &Dataspace,
    datatype: &Datatype,
) -> Result<Option<&'a [u8]>, FormatError>

Zero-copy read of contiguous raw data, returning a borrowed slice.

For contiguous layouts, returns a direct &[u8] slice into file_data. For compact or chunked layouts, returns Ok(None) — the caller should fall back to read_raw_data for those.