PAC format

Introduction

This page describes the package file format used by the original Imperium Galactica. The hu.openig.utils.PACFile class contains the routines to process a .PAC file.

Details

The file starts with a word, which specifies the number of entries (N) in the file.

Following N x 20 bytes contains the directory listing for each internal file, size and offsets within the file:

Offset	Description
00	The length of the following file name, up to 13 bytes
01 - 0D	The file name, unused bytes contain the dot (0x2E) characters
0E - 0F	The length of the file
10 - 13	The absolute start offset within the file

Unfortunately, this file format does not allow storing files larger than 64KB. Therefore, lot of the building images are stored splitted into two separated files within a package. The file format allows the file data to be non-contignous or not in the same order as the directory entries. The file is in little endian format.