GFA (File Format)

GFA (Good-Feel Archive) is an archive format developed by Good-Feel and used in some Nintendo 3DS games and software such as StreetPass Mii Plaza.

File Format

The file byte order is always little endian.

Header

Every GFA file begins with a 0x2C byte header structure.

Offset	Type	Description
0x00	Char[4]	File magic. Always GFAC in ASCII.
0x04	UInt32	Version number.
0x08	UInt32	Unknown. Always 1.
0x0C	UInt32	File Allocation Table offset.
0x10	UInt32	Size of File Allocation Table in bytes.
0x14	UInt32	GFCP offset.
0x18	UInt32	Size of GFCP in bytes.
0x1C	Byte[16]	Padding.

File Allocation Table

The Header is immediately followed by a File Allocation Table. It has the following structure:

Offset	Type	Description
0x00	Int32	Number of nodes.

Node

Followed by the number of nodes comes all node entries. Each entry has the following structure:

Offset	Type	Description
0x00	UInt32	File Hash.
0x04	UInt24	File name offset.
0x07	Byte	Unknown. Sometimes seen as 0x80.
0x08	UInt32	Size of the uncompressed file in bytes.
0x0C	UInt32	Uncompressed file offset, starting at the GFCP offset.

GFCP

The GFCP section contains file data. Its header has the following structure:

Offset	Type	Description
0x00	Char[4]	File magic. Always GFCP in ASCII.
0x04	UInt32	Unknown. Always 1.
0x08	Int32	Compression type: 0 = Uncompressed 1 = BPE 2 = LZ77 Wii Raw 10 3 = LZ77 Wii Raw 10 (as well?)
0x0C	UInt32	Uncompressed size.
0x10	UInt32	Compressed size.

After follows 4-byte aligned null-terminated strings that represent the filenames of the packed files.

File Data

The compressed data begins just after the the GFCP header.

Version List

Version	Found in
0.0.3.1	StreetPass Mii Plaza

Tools

The following tools can handle GFA files:

• (none)