Wexos: Imported from avsys wiki

2024-05-01T17:59:18Z

Imported from avsys wiki

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'''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:

{| class="wikitable"
|-
! 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:

{| class="wikitable"
|-
! Offset !! Type !! Description
|-
| 0x00 || UInt32 || '''Number of [[#Directory|directories]]'''.
|-
| 0x04 || UInt32 || '''Offset''' to the first [[#Directory|directory]]. Relative to the start of this block.
|-
| 0x08 || UInt32 || '''Total number of [[#Node|nodes]]'''.
|-
| 0x0C || UInt32 || '''Offset''' to the first [[#Node|node]]. Relative to the start of this block.
|-
| 0x10 || UInt32 || Length of the whole '''[[#String Table|string table]]'''.
|-
| 0x14 || UInt32 || '''Offset to [[#String Table|string table]]'''. Relative to the start of this block.
|-
| 0x18 || UInt16 || Next available '''[[#Node|node ID]]'''.
|-
| 0x1A || UInt16 || 1 indicates that the '''node ID''' of each [[#Node|node]] equals the index of the [[#Node|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.

{| class="wikitable"
|-
! 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|string table]].
|-
| 0x08 || UInt16 || '''[[#Hash|Hash]]''' of the directory name.
|-
| 0x0A || UInt16 || '''Number of [[#Node|nodes]]''' in this folder.
|-
| 0x0C || UInt32 || '''First [[#Node|node]] index'''. This is the index of the first [[#Node|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|directory]]. Otherwise it links to file data. Each entry is a 0x14 bytes structure.

{| class="wikitable"
|-
! Offset !! Type !! Description
|-
| 0x00 || UInt16 || '''Node ID'''.
|-
| 0x02 || UInt16 || '''[[#Hash|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''' x'''EFG''': 
* '''A''': Sets the compression type, if the file is compressed. 0 = [[Yay0]], 1 = [[Yaz0]].
* '''B''': 1 indicates that the file data should be loaded from the DVD whenever it's needed.
* '''C''': 1 indicates that the file data should be preloaded into ARAM.
* '''D''': 1 indicates that the file data should be preloaded into MRAM.
* '''E''': 1 indicates that the file is compressed. 
* '''F''': 1 indicates that this node is a '''folder'''. If it is a folder, node index and all compression flags are ignored.
* '''G''': 1 indicates that this node is a '''file'''.
|-
| 0x05 || UInt24 || '''Offset to a string''' into the [[#String Table|string table]]. Relative to the start of the [[#String Table|string table]].
|-
| 0x08 || UInt32 || '''File''': Offset to file data, relative to the start of the file data. 
'''Folder''': Index of the [[#Directory|directory]] that represents this folder.
|-
| 0x0C || UInt32 || '''File''': Length of the file data in bytes. 
'''Folder''': Unknown, always 0x10.
|-
| 0x10 || UInt32 || {{Unknown-left|'''Unknown'''.}}
|}

=== Special Nodes ===
There are two special folder nodes presented at the end of each folder, included in the count in the [[#Directory|directory]] owner. The first one is ".", and it links to current [[#Directory|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|info block]].

== Hash ==
In all [[#Directory|directory]] and [[#Node|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:

<pre>
public static ushort CalculateHash(string Name)
{
ushort Hash = 0;

for (int i = 0; i < Name.Length; i++)
{
Hash *= 3;
Hash += Name[i];
}

return Hash;
}
</pre>

= Tools =
The following tools can handle RARC files: 
* [http://www.wiibrew.org/wiki/ARCTool ARCTool], by [http://www.wiibrew.org/wiki/User:Tpw_rules Tpw_rules]
* [[Wexos's Toolbox]], by [[Wexos]]

[[Category:GameCube File Formats]]
[[Category:Wii File Formats]]

RARC (File Format) - Revision history

Wexos: Imported from avsys wiki