Difference between revisions of "Auto detection"

Note: I am not yet sure how to handle target_md5 here. Maybe we don't need it anymore, maybe it could be passed as a hint to <code> detectGames </code>.

The current file name substitution system, built around SubstResFileNames, tries to solve multiple goals at once: (TODO: Give a list here). This makes some things more complicated than necessary. Also, it can't do all that one would like to be able to do... for example, when used during detection, it should be possible to deduce language/platform information from those filenames (useful for the detector).

 

Also, there are some efficency issues: If we search through the full list of file name subsitutions for each game, we essentially arrive at a quadratical run time.

 

Taking a closer look at <code>substResFileNameTable</code>, one quickly notices that almost all entries in there really map a gameid to either a full fixed file name (usually for mac versions), or to a "pattern" filename (think of  GAME.LA0, GAME.LA1, GAME.LA2 etc.). The exception to this is the code to detect MM/Zak variants for NES and C64. If we add dedicated code for the latter, the table finally is reduced to what I just described: A map from gameids to file name "patterns".

 

Now, take a look at <code>ScummEngine::openRoom</code>. It actually also encodes a lot of knowledge about SCUMM filenames. This is duplicated knowledge. Instead of first putting effort into generating a "good" filename, and then putting more effort into trying to substitute that file name, and doing that over and over again -- wouldn't it be much better to check once which kinds of filenames are needed, and then always generate the right names immediately? In particular, the 'create' function already has to determine the file substitution required for that game... why throw that away?

Hence the idea is born to unify the knowledge / data found in <code>ScummEngine::openRoom</code> and <code>substResFileNameTable</code> into a single mechanism. This is why I wrote above that <code>detectGames</code> should return a SubstResFileNames (or equivalent recorde). We already pass that to the ScummEngine object. We simply extend this to allow to be used directly by <code>ScummEngine::openRoom</code> (and of course other methods) to generate suitable filenames from given data.

 

TODO: Finish this