public static string LookUpGameId(GameSourceBase gameSource)
{
string hash = CalculateGameChecksum(gameSource);
// Look it up!
GameRecord gameRecord;
GameRegistrar.gameDatabaseByCheckSum.TryGetValue(hash, out gameRecord);
// If we found a record, we're done!
if (gameRecord != null)
{
return(gameRecord.Id);
}
// (if we didn't, it gets messy...)
//////////////////////
// Try desperately to come up with a game ID to fill in for this unknown, rogue game.
// TODO: If at some point there's a nice (non-intrusive) way to let the user know
// that this game is unknown, then we should do it here. This code will only be able
// to come up with an Id that doesn't exist in the database. If there are two
// games out there that don't exist in the database, there's a chance that they'll
// use the same GameId, and therefore share save states. This isn't too likely, and
// if it happens, most users won't notice unless they play a lot of both offending
// games. That's why it would be good to notify users and hopefully get feedback
// early.
// But, of course, I really doubt this will ever be a problem.
// Start with the first 8 characters of the hash.
// (that's how the other items in the intial game database were made anyway).
string candidateId = null;
bool unique = false;
bool firstTry = true;
// As long as this game
do
{
if (firstTry)
{
candidateId = hash.Substring(0, 8);
}
else
{
candidateId = GetNextId(candidateId);
}
firstTry = false;
GameRecord existingRecord = null;
GameRegistrar.gameDatabaseById.TryGetValue(candidateId, out existingRecord);
unique = (existingRecord == null);
} while (!unique);
// Well, this key oughta do for now.
return(candidateId);
}
public static string CalculateGameChecksum(GameSourceBase gameSource)
{
//////////////////////
// Come up with MD5 hash of the first block of CD data.
byte[] checkSumSourceData = new byte[2048 * INITIAL_SECTORS_TO_READ];
for (int x = 0; x < INITIAL_SECTORS_TO_READ; x++)
{
unsafe
{
fixed(byte *dataPtr = &checkSumSourceData[x * 2048])
{
gameSource.ReadSector(new IntPtr((int)dataPtr), x);
}
}
}
return(GetHash(checkSumSourceData));
}