There are plenty, such as FCEUX, Nintendulator, and Nestopia. It's just that most are copylefted, and copyleft requires distribution of complete corresponding source code for the emulator.Bregalad wrote:Interesting. I am however surprised by the lack of "features", i.e. have to require to game-specific hacks for raster timing and playing OGG files for audio. It sounds quite chep, there's probably some emulators with GNU licences allowing re-use without asking anyone for permission... or isn't there any ?!
Mostly I've seen that in descriptions of obscure Japan-only mappers. (If an article that isn't about a Japan-only mapper uses "FCEUX's code does this", let me know and I'll evaluate it.) If a particular mapper implementation is the only GPL code in your project, and you remove that mapper from a branch of an emulator designed to support only a particular game that does not use that mapper, you no longer have to release your emulator under GPL. This means you can make a GPL version with all mappers and a permissive or LGPL version with few mappers, much as FFmpeg does with its configuration switches that enable use of GPL libraries.Sour wrote:There is so much information, even on the wiki (How many times have you read "FCEUX's code does this", "Nestopia's code does that" while reading the wiki?) that is extracted from the source of current GPL-licensed emulators
Copying an idea, process, or method of operation, as opposed to its expression, is not restricted by copyright. This means that if a particular piece of hardware is observed to do something, and the sequence and structure of your code is determined by that behavior, and you don't copy variable names or other "window dressing", it does not infringe.Sour wrote:that it pretty much makes it impossible to not release an emulator as GPL (unless you just ignore the license's restrictions).