Old Engine/File Archive

This file format was used by RS2 and RSC. Files are compressed using BZip2.

The BZip2 signature (4 bytes) is intentionally left out to save space, and it must be prepended before decompressing.

File Header

Purpose	Data Type
Unpacked size	SWord
Packed size	SWord

If the unpacked size and the packed size do not match, decompress the archive now.

Archive Header

Purpose	Data Type
File count	Word
... for N files: ...
File hash	DWord
File uncompressed size	SWord
File compressed size	SWord

When reading the file, if the archive was not decompressed before, decompress the file once it's read.

Example:

this.unpackedSize = readSWord(src);
this.packedSize = readSWord(src);

if (this.packedSize != this.unpackedSize) {
	let data = bz2.decompress(concatenate(Uint8Array, BZ2_HEADER, src.buffer.slice(src.offset)));
	src = { buffer: data, offset: 0, length: data.length };
}
this.data = src;

this.fileCount = readWord(src);
this.fileHash = [];
this.fileSizeInflated = [];
this.fileSizeDeflated = [];
this.fileOffset = [];

let offset = src.offset + (this.fileCount * 10);
for (let file = 0; file < this.fileCount; file++) {
	this.fileHash[file] = readDWord(src);
	this.fileSizeInflated[file] = readSWord(src);
	this.fileSizeDeflated[file] = readSWord(src);
	this.fileOffset[file] = offset;
	offset += this.fileSizeDeflated[file];
}