WAD64

WAD64 is a modern version of the classic DOOM archive format. It is more or less an identical archive file format, with larger fields.

Features

• Full random access to individual lumps
• 64-bit file offsets
• Up to 2^63 - 1 directory entries
• 255 byte long lump names

Differences between classic DOOM WAD and WAD64

• WAD64 lump names should be encoded as UTF-8. If a lump name contains any null bytes, the must appear last. Also, the lump name must end with a null byte. That is why only 255 bytes are allowed. The last byte must always be a null byte.

• WAD64 forbids overlapping lumps. Note however, that a file of zero length, may have the same start offset as any other file. This is similar to the [[no_unique_address]] attribute in C++.

Common archive features that are not supported nativly

• Hierarchical directory structures. However, since it is possible to have longer lump names, it can be emulated by following some convention. For example, it is possible to us / in lump names. Another possibility is to have WAD:s inside WAD:s. This works, because the file format allows full random access. The utility application wad64 uses the first approach because it is simpler to implement.

• Compression/encryption. It is possible to add compressed/encrypted lumps (in fact, a lump can contain anything), provided that the reader knows what compression/encryption scheme is used. The directory cannot be compressed/encryption, because then it is not possible to find the data.

• File metadata. If desired, a special file such as a medadata.json file can be added to the archive

• Any checksums. If desired, this can also be added by adding a special file to the archive