the best thing about ghidra is that no matter which version you're using, setting equates sometimes just doesn't work, but if you google it, you only find several bug reports which basically say "equates don't work" and then it's "closed, fixed in X.Y.Z" and that's a version you're upgraded way past

port_out(0x3c4,0xf02);

I SO WANT TO EQUATE 0x3C4 TO THE VGA SEQUENCER INDEX REGISTER BUT I CAN'T

the weird thing is the equates table says it's been set, says there's a reference to it at that address, but if I go to that address, there's nothing. just 0x3c4
OH GOODY I found a mistake in OSDEV
their docs on the PC gameport are incorrect
and I can't rename some local variables either!?
what the fuck, ghidra?

okay I've fixed OSDEV:
https://wiki.osdev.org/Game_port

They had the introduction of the gameport listed as "the PCjr" (it's from 1981, the PCjr came out in 1984... and didn't even have this gameport connector!) but more importantly, they had the order of the joystick axises wrong.

Game port - OSDev Wiki

and the IBM Game Control Adapter is mentioned in the August 1981 IBM PC Technical Reference, so IBM clearly had the gameport ready at day one of the IBM PC, even if it was an optional add-in.
mind you, on the IBM PC, just about everything is an optional add-in. You get a keyboard and a cassette port for free: you want graphics/text, floppies, hard drives, serial/parallel ports? that's extra.

god. Duke Nukem 1 has so much copy-pasted code.
Like, there's a ton of hint dialog boxes like "You need the key to open this door!" or "you get more points if you catch the balloon"

you'd think they'd just have ShowMessage() and pass it a different string, but nope. it's a different function.

LEARN TO WRITE REUSABLE FUNCTIONS

interesting. there's 12 hint-variables which are used to make sure you don't get hinted for something you've used before.

One of them is still maintained, but not used. So there must have been another hintable thing that got dropped

although I'm looking at DN1, episode 1. Maybe it does do something in DN1E2 or DN1E3?
because yeah this was also the era where you'd have 3 separate executables for 3 separate episodes of the same game

like, it has a function that loops through all 16 color indices and sets them to black. it takes one parameters, which tells it how long to wait between each color is set, so it'll fade slowly to black, instead of being instant.

there's also an identical function that does the same, but sets it to white, instead.

so instead of fade_screen(COLOR_BLACK) and fade_screen(COLOR_WHITE), it's two separate functions!

@foone If it was fading each index (slowly changing to the target, rather than just switching one palette entry at a time), then I could understand making it two functions, as it probably makes the code a bit simpler.

Of course, if it's just:

for(int i=0; i<16; i++) { palette[i] = 0; }

then separate functions are less attractive.

Who said old code was more efficient?