Exactly. Libraries won't even help here. They're typically bound to non-commercial and/or copyleft licenses. And then you'd need one for every language imaginable. ROM hackers are extraordinarily diverse in their choice of programming languages. We have C, C++, C#, VB.NET, Java, Pascal, Delphi, PHP, etc etc.

An algorithm that requires mastering a thesis to implement (xdelta, bsdiff) fails right off the bat. Nobody else can implement that.

You guys have been really patient with the patching business. I pretty much put my format on hold to rewrite xkas. Now that this is finished, I'm back to just one open project, so I have room for a second.

UPS is basically IPS with XOR instead of NEW byte storage, making the format two-way. It also has a simplistic packed pointer approach that allows for infinite growth, and a smarter RLE than IPS. Throw in filesizes and CRCs of the source, dest and patch file itself, and that's it.

The idea would be for the patcher to enforce a rule to ignore headers that do not affect emulators, and to force headers that do. Eg SNES headers are out, NES headers are in. Supporting NES vs UNIF differences et al are beyond the scope of the patcher. When you force the patching algorithm to accommodate the infinite stream of systems out there, you'll never end up with complete implementations. Better to make a generic format and enforce rules (eg here, as well as in most patch creators, which can be changed in the future -- unlike the patch spec itself) to prevent header hell. The CRCs will greatly assist in detecting errors, and it's easy to make a patcher that auto-removes headers if you want.

Of course, I've had the spec ready for a long time now. Just been really busy with a lot of stuff. I suppose I can just post the spec again if anyone really wants to kickstart the process.

Just check out PPF Studio, you can make a "General" PPF patch with it. That can be used on any files.

I just made a PPF patch of my Famicom Wars translation, and applied the PPF to a fresh Japanese rom, so I know it works.

I just use PPF-O-Matic 3.0. All you have to do is change the drop down box to "All Files"

great. tested PPF yesterday with a GBA game, and it seems that it worked perfectly!

but, It became bigger than IPS. PPF patch got ~700kb. IPS only 310kb.

It's a better choice for platforms that IPS system don't work. I'll test it with DS later.

I totally agree on that matter, especially because I'm sooo lazy. xD My custom patch format for ToP is so simple it can make any serious programmer laugh. Probably the only interesting feature is the possibility to unpack archived files, patch the segments, and rebuild the new file. And each patch segment is huffman compressed, so even if the format wastes A LOT of space (you can have 9 bytes only to patch a 1 byte sequence xD) it doesn't really matter as huffman solves the issue.

This is off-topic, but there seems to be a little bit o’ corruption at the end of the document.

Back on-topic, even simple patching formats aren’t so bad. You could easily stopgap IPS by allotting more bytes for addresses (call it, say, IPS+ or something and use IFF for silliness!). The main problem seems to be that everyone wants to roll the “latest and greatest”, and the additional complexity does have that fun effect of making people not work on it or use it for whatever reason.

(byuu, the UPS format you mentioned has piqued my curiosity... could you post the spec, please?)