RARC (File Format)
RARC files are archive files used in some Wii and GameCube games, such as Super Mario Galaxy and Super Mario Galaxy 2. The directories are always stored inside a root directory.
File Format
Header
The file starts with a header that is 0x20 bytes long:
| Offset | Type | Description |
|---|---|---|
| 0x00 | Char[4] | File magic. Always RARC in ASCII. |
| 0x04 | UInt32 | Length of this file in bytes. |
| 0x08 | UInt32 | Length of this header in bytes. Always 0x20. |
| 0x0C | UInt32 | Offset to file data. Relative to the end of this header. |
| 0x10 | UInt32 | Total size of all file data. |
| 0x14 | UInt32 | Size of file data which is preloaded into MRAM. |
| 0x18 | UInt32 | Size of file data which is preloaded into ARAM. |
| 0x1C | Byte[4] | Padding. |
Info Block
Directly after the header comes the info block. It is a 0x20 bytes structure as follows:
| Offset | Type | Description |
|---|---|---|
| 0x00 | UInt32 | Number of directories. |
| 0x04 | UInt32 | Offset to the first directory. Relative to the start of this block. |
| 0x08 | UInt32 | Total number of nodes. |
| 0x0C | UInt32 | Offset to the first node. Relative to the start of this block. |
| 0x10 | UInt32 | Length of the whole string table. |
| 0x14 | UInt32 | Offset to string table. Relative to the start of this block. |
| 0x18 | UInt16 | Next available node ID. |
| 0x1A | UInt16 | 1 indicates that the node ID of each node equals the index of the node. |
| 0x1C | Byte[4] | Padding. |
Directory
A directory represents a folder. All files contains a root directory which links to all other files and folders. Each directory is a 0x10 bytes structure.
| Offset | Type | Description |
|---|---|---|
| 0x00 | Char[4] | Some kind of identifier. The root has ROOT, other nodes have their first 4 characters of the name in upper case. If the length of the node's name is less than 4, then the rest of this string is padded with spaces. |
| 0x04 | UInt32 | Name offset. Relative to the start of the string table. |
| 0x08 | UInt16 | Hash of the directory name. |
| 0x0A | UInt16 | Number of nodes in this folder. |
| 0x0C | UInt32 | First node index. This is the index of the first node that is part of this folder. |
Node
A node can either be a file or a folder. If it's a folder, then it refers to a directory. Otherwise it links to file data. Each entry is a 0x14 bytes structure.
| Offset | Type | Description |
|---|---|---|
| 0x00 | UInt16 | Node ID. |
| 0x02 | UInt16 | Hash of the node name. |
| 0x04 | Byte | Bit flag that specifies the node type and what this node contains. This is usually 0x02 for folders and 0x11 for files. ABCD xEFG:
|
| 0x05 | UInt24 | Offset to a string into the string table. Relative to the start of the string table. |
| 0x08 | UInt32 | File: Offset to file data, relative to the start of the file data. Folder: Index of the directory that represents this folder. |
| 0x0C | UInt32 | File: Length of the file data in bytes. Folder: Unknown, always 0x10. |
| 0x10 | UInt32 | Unknown. |
Special Nodes
There are two special folder nodes presented at the end of each folder, included in the count in the directory owner. The first one is ".", and it links to current directory. The second one is ".." and links to the parent directory.
String Table
The string table consist of null-terminated strings. The offset and length of this string table is stored in the info block.
Hash
In all directory and node. there is a hash of the name stored. To calculate the hash you need to loop through each character. Start with the hash as 0. For each character you multiply the hash by 3 and then add the character's value to the hash. The algorithm is demonstrated using the following C# code:
public static ushort CalculateHash(string Name)
{
ushort Hash = 0;
for (int i = 0; i < Name.Length; i++)
{
Hash *= 3;
Hash += Name[i];
}
return Hash;
}
Tools
The following tools can handle RARC files:
- ARCTool, by Tpw_rules
- Wexos's Toolbox, by Wexos
