|Cross-link to the Ocarina of Time wiki: Filesystem|
Ocarina of Time, Majora's Mask, and all of their separate versions & ports use an identical filesystem. It's primary purpose is to provide an easy mechanism to locate files when the rom is compressed. The dmadata file consists of a table of records for every file in the game (including itself).
The first entry of the file table is always the "makerom" file, located at 0x00000000 to either 0x00001060 for most versions, or 0x00001050 for the iQue.
One entry for a file is 0x10 bytes, and of the following form:
|Virtual Address (VRom)||Physical Address (Rom)|
The virtual rom address assigns a file a virtual location, and sets the file's size. This virtual location represents the location at which the file will exist if all of the files in the rom were decompressed, and thus acts as an identifier for a file or a portion of it's data. In a fully decompressed rom, a file's virtual address will be the same as it's physical address. The physical rom address points to where the file is actually stored in rom. A physical address either points to an uncompressed file, a compressed file, or no file at all (Majora's Mask).
- If a file is compressed, the start and end physical addresses will be set to the start/end of the compressed file in the rom.
- If a file is not compressed, the start physical address will point to rom, but the end address will be 0.
- If a file does not exist, both start and end physical addresses will be FFFFFFFF.
Consider these examples:
<= COMPRESSED DATA => Offset 0x0001C1C0 in the debug ROM Virtual Mapping Physical Mapping 00A3A000 00A3EB80 009BA6B0 009BBA50 00A3F000 00A42300 009BBA50 009BD150 00A43000 00A4A780 009BD150 009C0310 <= DECOMPRESSED DATA => Offset 0x0001C1F0 in MM J Virtual Mapping Physical Mapping 00A4B000 00A4C310 009C0310 00000000 00A4C310 00A55660 009C1620 00000000 00A55660 00A68270 009CA970 00000000
As you can see in the decompressed data example, these three files are decompressed and mapped to a certain location, with their last pointer being set to 00000000. Since the file size of the file in the ROM is identical to the mapped one, the last pointer can be set to 00000000 without losing information. In short: the game calculates the size of the block via the virtual mapping (when dealing with decompressed data). In the compressed data example, however, the physical mapping points to a Yaz0 block in the ROM, which is then decompressed and mapped to the location in the first offset pair.
Majora's Mask Debug Rom has a filename table similar to Ocarina of Time's Debug Rom, but it only lists the names of the scene files, and some of the scenes it refers to are removed. In order to build a more complete filename list, Majora's Mask 3d was used to identify files.