Foone🏳️⚧️
Bad idea: build a captcha library that embeds DOSBox so it can make you beat levels/puzzles from DOS games to continue.
Prove you're a human! Beat Lifewater Oasis from Commander Keen 4! Defeat the Yeti in Kings Quest 5! Make sure 15 lemmings survive! Get the sword in Prince of Persia!
Foone🏳️⚧️
Honestly just making it do The Incredible Machine puzzles would be hilarious
Foone🏳️⚧️
Same form lemmings... God, is it just all puzzle games?
Foone🏳️⚧️
I have thought about adapting Simon Tatham's puzzle collection to a captcha. Like it just gives you a puzzle with no instructions.
Foone🏳️⚧️
!
Where in the world is Carmen Sandiego!
You catch the culprit of the current case, using the clues and your geographic knowledge and Encyclopedia!
Foone🏳️⚧️
Oregon Trail would also be funny.
To prove you are a human, get to Oregon.
Foone🏳️⚧️
We use geo-ip to automatically allow anyone showing up as accessing the site from the state of Oregon, of course.
Foone🏳️⚧️
(that is only one slight degree sillier than something I have done professionally for a website)
Foone🏳️⚧️
Chip's Challenge levels would also be funny.
Foone🏳️⚧️
The edutainment puzzles from the doors in Super Solvers: Gizmos and Gadgets!
Osmose
@foone brb adding an error handler that says BUMMER whenever the API returns a 401
Foone🏳️⚧️
You know, I was just thinking yesterday I should reverse engineer that game, but I don't really have a reason to.
Now I do.
Foone🏳️⚧️
"have a population of at least 20,000 within 5 years in this game of SimCity 2000"
Foone🏳️⚧️
Just throwing surfers randomly in point and click adventures and then telling them to find an item would also be funny.
Do you know where to get the Cloaking Belt in Space Quest 3? How about the box of electronic bunnies in Full Throttle?
Where's the Old Book on Hugo 3: Jungle of Doom?
Foone🏳️⚧️
@gryzor madness!
Martin Marconcini
@foone how about an incredible machine *with* lemmings?
Foone🏳️⚧️
@itec yes but running the actual game
![itec [☎️4832]](https://social.076.moe/avatar/134544-48-20241125082439.webp){kind=small}
itec [☎️4832]
@foone something like doom captcha?
https://vivirenremoto.github.io/doomcaptcha/
Foone🏳️⚧️
@lritter that'd be fun! significantly more likely to get your ass sued off, sadly.
Leonard Ritter
@foone warioware but as captcha
Foone🏳️⚧️
Seems Gizmos and Gadgets is a 16-bit EXE compiled with Borland Turbo C++ (no floating point support)
Foone🏳️⚧️
oh goody my favorite, OVERLAYS!
as if segmented code wasn't enough of a pain, where you don't know where a pointer points to unless you see how it's used, now you don't know what code is CURRENTLY loaded at that position, because it changes!
Foone🏳️⚧️
step up: find the fade out.
see the game fades out when you go into a door. find where that code is, then see what gets called next.
finding a fade out should be easy: look for when they reprogram the VGA palette registers to dim every color to black.
Foone🏳️⚧️
@gh oh that'd be fun.
Graeme Hamilton
@foone Or for the non-gamers: “Edit these CONFIG.SYS and AUTOEXEC.BAT files so that you have both CD-ROM access and mouse driver working, while also having 600KB of available conventional memory.”
We’d need anti-cheat to prevent the use of MEMMAKER though…
Foone🏳️⚧️
found 5 places the palette is reprogrammed
and all are in overlays. ugh.
Foone🏳️⚧️
OKAY realistically this is a game that features several different games you can play, and games between games. they're just gonna make each one a separate overlay.
so I need to figure out how it shifts overlays and how to track which overlay is active
Foone🏳️⚧️
looks like the separate game engines are called puzzler, electric, and simple.
Foone🏳️⚧️
I love when games use __FILE__ in their assertions. please tell me all your filenames please
Foone🏳️⚧️
can I not set an I/O breakpoint in dosbox-x's debugger? I forget.
Foone🏳️⚧️
@enno mean
but yeah, clearly.
Enno Rehling
@foone some of these could probably do double duty as age verification challenges .
Foone🏳️⚧️
oh sweet laser jesus I found the upload palette function and THEY UNROLLED IT
Foone🏳️⚧️
why do:
for(int i=0;i<256;i++){
upload_color(i,palette[i]);
}
when you can do
upload_color(0,palette[0]);
upload_color(1,palette[1]);
upload_color(2,palette[2]);
upload_color(3,palette[3]);
upload_color(4,palette[4]);
upload_color(5,palette[5]);
and just repeat 251 more times
Foone🏳️⚧️
the worst part is that this was done with a compiler from 1991 so there's no way it unrolled the loop itself. they did this manually
Foone🏳️⚧️
@saua it runs slightly faster. like a couple cycles per "iteration".
This is aiming at CPUs so slow that that might matter
saua
@foone Any idea why? I have extremely little experience with programming in that era, but I remember that code size was always a serious concern ... so unrolling it sounds like a bad idea, unless they really needed it for performance.
Foone🏳️⚧️
oh that's cute. their set_palette function takes two arguments: a pointer to the palette, and a number of extra palettes to apply.
so they could set up an array of palettes in decreasing brightness, and just do set_palette(&fade_pallets[0], 64) to go through them.
but the same function is a regular one-time set_palette if you just pass 1 for the second argument.
Foone🏳️⚧️
@simonzerafa in 1991? I don't think so. Not a for loop this big.
Simon Zerafa
No compiler flags that would do this? 🤔🤷♂️
Foone🏳️⚧️
"hey ghidra what calls set_palette?"
"I don't know! you're in 16bit segmented mode! pointers are MEANINGLESS
Foone🏳️⚧️
ahh, nope! I misidentified it.
the second parameter on set_palette is how many frames to set it for.
The same palette gets set.
it vsyncs every time so this is a set_palette that's also a timing function
Foone🏳️⚧️
or maybe not? it's too 2am to tell.
ANYWAY I'm currently debugging through a function that's 256 palette entry uploads and my debugger has no "run until return" function so I have to manually hit next instruction SO MANY TIMES
Foone🏳️⚧️
(approximately 1536 times)
Foone🏳️⚧️
@th yup
Trammell Hudson
@foone the only thing better than __FILE__ is __func__
Foone🏳️⚧️
this set_palette code got loaded into the segment 0BBC, one of the only 16-bit DOS segments marked red in shinigami eyes
Foone🏳️⚧️
interesting: the same function is called to fade a palette to blackness and to fade a palette to blackness.
I wonder if it's specialized to just be palette to black and vice versa, or if it does arbitrary fades between two palettes?
![Asta [AMP]](https://social.076.moe/theme/neo-hacker/default-avatar-stream.png){kind=avatar}
Asta [AMP]
@foone@digipres.club maybe they wanted to experience the joys of funroll-loops all by themselves
not much else going on in 91
Foone🏳️⚧️
@aud good point, it was a famously uneventful year
Foone🏳️⚧️
I'm staring at this code going "if it was less 2am, I could understand this math"
Foone🏳️⚧️
this math:
local_8 = (int)(0x3f / (long)param_1) + 1;
iVar6 = 0;
do {
uVar7 = (undefined2)((ulong)param_2 >> 0x10);
uVar8 = (undefined2)((ulong)param_4 >> 0x10);
iVar4 = (int)param_4;
uVar1 = (int)*(char *)(iVar4 + iVar6) - (int)*(char *)((int)param_2 + iVar6);
uVar2 = (int)uVar1 >> 0xf;
local_608[iVar6] = (char)((int)((uVar1 ^ uVar2) - uVar2) / local_8) + '\x01';
iVar6 = iVar6 + 1;
} while (iVar6 < 0x300);
Kee Hinckley
@foone Loop unrolling is older than that though. Although maybe not on these platforms, unless they were cross compiling?
It's in the "dragon book" on compiler design in the 70's. And by the 80's, in the workstation space, that and other techniques were common (my ex-wife worked on compiler optimization back then).
Foone🏳️⚧️
@nazgul I know it existed before, I just don't think DOS compilers of the time did it this much.
Foone🏳️⚧️
@oblomov FACK
yeah
Oblomov
@foone you also wouldn't have posted about fading the palette to blackness being the same function as fading the palette to blackness ;-) (I assume one of those was supposed to be whiteness and/or a from?)
Foone🏳️⚧️
found the INT31!
we've got OVERLAYS FOR SURE!
Foone🏳️⚧️
wasn't there some kind of tool that could flatten out an overlay'd file, at least enough for ghidra to load it?
Foone🏳️⚧️
https://github.com/NationalSecurityAgency/ghidra/issues/5543
oh this is more complicated than I can figure out at 2:42am
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