Print view Previous topic | Next topic

Topic Starter	Topic: [Q4] Checksum calculation?
Foo Timed Out Joined: 02 Aug 2000 Posts: 38064	Posted: 05-27-2006 04:11 AM                    Trying to calculate the checksum for PK4s manually (in PHP) but can't find any information on the kind of crc check which Q4 performs. It's not crc32, I get a different checksum than Q4 gets with the 'path' command on the same file. Any ideas? _________________ "Maybe you have some bird ideas. Maybe that’s the best you can do." ― Terry A. Davis
Top

kaffeedoktor Gibblet Joined: 09 Feb 2004 Posts: 24	Posted: 10-03-2006 06:20 AM                  Maybe I replay a bit late, but the checksum used to identify PK4s is an MD5, which you can create in PHP using the md5_file( ) method.
Top

Foo Timed Out Joined: 02 Aug 2000 Posts: 38064	Posted: 10-03-2006 06:22 AM                    The MD5 output I'm familiar with is a 128-bit hash, whereas the checksums listed for quake 4 are in the format 0xAC34CA, and soforth? _________________ "Maybe you have some bird ideas. Maybe that’s the best you can do." ― Terry A. Davis
Top

kaffeedoktor Gibblet Joined: 09 Feb 2004 Posts: 24	Posted: 10-03-2006 06:42 AM                  Sorry, I got sth wrong. For ingame usage Q4 uses an 8 byte MD5 blockchecksum, which is build as: val = digest[0] ^ digest[1] ^ digest[2] ^ digest[3]; (that's code from idlib, val & digest are unsigned long values). E.g. a 32 byte MD5 0x0123456789ABCDEF0123456789ABCDEF will get split into 0x01234567, 0x89ABCDEF, 0x01234567, 0x89ABCDEF These 4 parts will are used to calculate the resulting 8-byte blockchecksum using the OR operation.
Top

Quake3World.com | Forum Index | Programming Discussion