pub fn map_dir_entry(dir: *Directory, page: u32, phys_addr: u10) void {
    var entry: *DirectoryEntry = &dir.entries[page];
    entry.accessed = false;
    entry.caching_disabled = false;
    entry.four_megabyte_pages = true;
    entry.available = 0;
    entry.present = true;
    entry.user_level = false;
    entry.writable = true;
    entry.write_through = true;
    entry.zero = 0;
    entry.page_phys_addr = phys_addr;
}