Category:FastFiles

FastFiles are the CoD engine's way of storing Zone files. FastFiles (FFs) almost always have some sort of RSA2048 signature, a zlib compression along the way, and then on later CoDs some encryption. The Zones are a library of assets. Every FF in every CoD game starts the same way...

So by reading the version of the input FF, you can tell what system and game the FF is from. Note that pre-alpha versions of Call of Duty 4 are missing the version integer, and must be handled specially. Also keep in mind that the Quantum of Solace FFs are missing the magic in the struct above.

Stream Blocks

After the Zone (XFile) is extracted from the fastfile, you read the block sizes of each g_streamBlock allocation. This determines how much memory to allocate to each stream to read data into. Each block stream has a specific role in the data that is read and it goes as follows:

One distinction is that PC uses virtual for a load of loading where PS3 mainly uses large.

Pointers in Zone Files

Pointers can be classified as one of the following:

• 0: null, no data follows
• -1: inline, data follows after the struct, usually in order but NOT ALWAYS
• -2: insert, space is allocated in the stream block and inserted into later
• else: everything else is an encoded offset, it contains which block and offset it's pointing too.

For encoded offsets the first 4 bits (or 3 bits in BO2) are extracted and used as an index for the g_streamBlocks array. The other bits are the offset and is added to the data pointer in g_streamBlocks.

Encoding

int EncodeOffset(int blockIndex, int offset)
{
    return (blockIndex << 28) | (offset + 1);
}

The offset is only correct after the zone file has been loaded in memory. This is because some data is relocated (aligned) which changes the size of the zone. Some differences:

• strings are aligned by 4 bytes
• asset headers are stored in pools
• sound, image, and shader programs are stored in pools
• zone header is removed