.HOG archives¶

The game's assets live in .HOG files, which use Electronic Arts' BIGF container. A 16-byte header is followed by a directory, then the members packed back to back with no padding and no alignment.

Every integer in the container is big-endian.

sltool hog info <archive>              # size, member count, how much is compressed
sltool hog ls <archive>                # offset, stored size, real size, name
sltool hog extract <archive> <dir>     # decompressing by default; --raw to keep members as stored
sltool hog pack <dir> <archive>        # pack a folder's files; --store: compress only what must be;
                                       # --checksum: write <archive>.sha256 beside it
make assets                            # extract resource.hog and pilots.hog into game/assets

Header¶

Directory¶

Entries follow the header at offset 16, packed with no alignment:

Entries are variable-length, so the directory can only be read by walking it; there is no index.

Names form a flat namespace with no directories and no path separators, and are not normalised:

• Case is inconsistent. interpal.TGA and interpal.tga are different members of resource.hog.
• Names may contain spaces, for example Boridin gun dest.SHP.
• Names are not unique. Some names in resource.hog appear twice, and the two members are usually different sizes, so they are different assets rather than redundant copies. sltool hog extract gives the later member a ~2 suffix before its extension so nothing is lost, including where two names differ only by case and would collide on a case-insensitive filesystem.

Trailing filler¶

Two of the five shipped archives, msspeech.hog and pilots.hog, count one more entry in their header than their directory holds.

The extra record is 0xCD filler, the pattern MSVC writes over uninitialized memory, and it sits past the end of the real directory. The members themselves are unaffected: in every archive they form one contiguous run from the header's data offset to the last byte of the file, with no gaps. A reader should validate each entry and stop at the first one that is not a plausible record, rather than trusting the count.

The shipped archives¶

The game opens the discs' archives one at a time, as it needs them (cd_hog_open, Movies), and Bink reads a movie from one as it is stored (hog_locate).

OpenReliant's mods, which are archives in this format or folders of files, replace the files with the same names in any of these archives and among the game's loose files (Modding).

resource.hog's members by extension: .shp models, .spr sprites, .tga images, .dte missions, .fat sound banks, .fnt fonts, .ccb colour tables, and five .bin files: the four stat tables and profile.bin.

Writing an archive¶

hog.build lays an archive out as the shipped ones are: the header, a record and a name for each member in the order given, then the members back to back from the header's data offset to the end of the file, with no trailing filler. A name is one or more bytes of printable ASCII, as the directory's reader takes it (hog.validName). Names are not made unique.

sltool hog pack makes an archive of every file of a folder, each a member of its own name, in name order. It stores each member as hog.packMember finds best:

• A RefPack stream (compressing) where one is smaller and the game can expand it in place, and otherwise, or with --store, the file as it is, which the game reads verbatim.
• A file that begins 10 FB, whatever the packing: the game takes it for a stream. It goes in as it is only where it is one that expands to its declared size in place (refpack.loadsInPlace), as sltool hog extract --raw gives a packed member. A stream over the bound, from another tool say, would overwrite the heap as the game loads it, so what it expands to is packed in its place. A file that is no such stream but only begins as one is compressed, having no form the game reads as it is. Where no stream of it loads, the pack fails.
• Movies (.bik) and face films (.fm8) as they are, whatever they begin with: the game reads both where they lie. Bink opens a movie in the archive once hog_locate (0x004C83F0) has found it, and hudmovie_play (0x0048D120) finds a film with hog_seek (0x004C8370) and reads it from the archive's file where the seek leaves it. Neither goes through hog_read_file, the one path that expands a packed member.

The ~N suffix extract gives a repeated name stays in the member's name.

With --checksum, pack also writes a checksum file next to the archive, named after the archive plus .sha256, in the format sha256sum uses. OpenReliant checks a mod's archive against it when it loads the mod (Modding).

RefPack compression¶

Compressed members begin with 10 FB and are decompressed transparently by sltool hog extract. The codec is EA's RefPack, also called QFS, and named FB10 after those two bytes. See refpack.md.

Compression is per member, not per archive, and is a property of the archive rather than of the file type: the same extensions appear compressed in resource.hog and uncompressed on the discs.