def METHOD_NAME(cls, read: MappaGBinReadContainer, pointer_beg, pointer_end):
    assert pointer_end > pointer_beg
    # The zeroth floor is just nulls, we omit it.
    empty = bytes(G_FLOOR_IDX_ENTRY_LEN)
    assert (
        read.data[pointer_beg : pointer_beg + G_FLOOR_IDX_ENTRY_LEN] == empty
    ), "The first floor of a dungeon must be a null floor."
    floors = []
    pointer_beg += 4
    for i in range(pointer_beg, pointer_end, 4):
        floor_data = read.data[i : i + G_FLOOR_IDX_ENTRY_LEN]
        floors.append(MappaGFloor.from_mappa(read, floor_data))
        if i >= read.dungeon_list_index_start:
            break
    return floors