FPACker

Tool to pack and unpack FPAC (.pac) files used in Trails in the Sky 1st Chapter / Sora no Kiseki the 1st

Usage

Run ./FPACker for help

Note that if you are on Windows, you must either run this program from a msys2 shell, or have msys-2.0.dll in the same directory as the executable.

Features

• Unpack all files
• Pack directory (Does not currently always make 1:1 FPACs with the originals, but they should still work ingame)

Supported Games

• Trails in the Sky 1st Chapter / Sora no Kiseki the 1st

How to Build

Clone this repository, then install gcc, make and cmake, then run the following commands

mkdir build_release
cd build_release
cmake ..
cmake —build . —config release

If you are on Windows, you must use Msys2.

Thanks to

• lowpolysnake for vector.h
• Martin Pool for strnatcmp.c / .h
• The sharun dev team
• The people on the Kiseki Modding Discord server.

The FPAC file format

This is a quite simple archive format. No compression is used.

Header

char fpac_magic[4]  //File signature, value is 1128353862 / 0x46504143 (FPAC)
u32 n_of_files //Number of files in the archive
u32 first_file_address //Address of the 1st file's 1st data section byte
u32 unk_magic //Unknown u32, seems to always be set to 1

File Entry

File entries are sorted by filename_crc32 in ascending order.

u32 filename_crc32 //crc32 hash of the filename string (excluding null terminator) XOR'd with 0xFFFFFFFF (thanks to hell259 for figuring this out)
u32 padding //Literally nothing, set to 0
u64 filename_string_address //Address of the first char of the filename string.
u64 file_size //Size of the file in bytes
u64 file_data_address //Address of the first byte of the file's data section

File

Both filename strings and files' data sections are sorted with seemingly natural sorting. However, this doesn't seem to actually matter ingame.

char* filename //NULL-terminated string that represents the full path of the file.
u8 data[file_size] //Uncompressed data of the file