Commit Graph

8 Commits

Author SHA1 Message Date
nmlgc e55a48b700 [Decompilation] [th01] master.lib resident palette function reimplementations
Which store colors as GRB, as suggested by the structure's ID string.
Even master.lib's own functions add an additional XCHG AH, AL
instruction to get colors into and out of this format. MASTER.MAN
suggests that it's some sort of standard on PC-98. It does match the
order of ths hardware's palette register ports, after all.
(0AAh = green, 0ACh = red, 0AEh = blue)

Now we also know why __seg* wasn't used more commonly, as lamented in
c8e8e98. Turbo C++ simply doesn't support a lot of arithmetic on
segment pointers.

And then that undecompilable far call to a function within the same
segment, but inside a different translation unit…
Also, thanks again to Egor for the SCOPY@ hack that debuted in 0460072.
Would have probably struggled with this a lot more without that.

And *then* you realize that TH01 effectively doesn't even use the
resident palette. 😐

And yes, we're procrastinating the whole issue of potentially using
a single translation unit for all three binaries by using a common
segment name, because it *really* isn't that easy.

Completes P0066, funded by Keyblade Wiedling Neko and Splashman.
2020-01-05 20:23:27 +01:00
nmlgc 5f4f5d87dc [Decompilation] [th03] Shot update and render functions
Meh, can't overload arithmetic operators that take a Subpixel without
generating a needless load and store, even with -Z. But heck, slightly
uglifying subpixel/subpixel arithmetic is exactly the right trade-off.

Completes P0061, funded by Touhou Patch Center.
2019-12-05 21:41:31 +01:00
nmlgc da27eb4c31 [Decompilation] [th05] Yuuka's shot control functions
Ooh, shot position being determined by RNG at lower shot levels? That's
some RNG manipulation TAS potential right there! Maybe.

Part of P0037, funded by zorg.
2019-10-14 23:54:29 +02:00
nmlgc db4de240e9 [Decompilation] Prepare the C side for the shot type control functions
That should make this convoluted copypasta a bit easier to read. And
sure, I could have done something about the loop as well, but
SHOT_FUNC_INIT already hides enough control flow behind a macro…

Part of P0037, funded by zorg.
2019-10-14 23:42:20 +02:00
nmlgc 82b0e1db24 [Reverse-engineering] [th05] Player shot cycle bitflags
A TH05 innovation that actually makes the game code easier to read?!
Although it was quite hard to actually reverse-engineer it, with the
confusing flag ordering pointing to some deeper meaning behind the
flags, which really doesn't exist.

Completes P0036, funded by zorg.
2019-10-14 23:42:09 +02:00
nmlgc a533b5d3ea [Reverse-engineering] [th04/th05] Player sprite area invalidation
And once again, the TH05 version is un-decompilable. :/ It was pretty
close this time, though, as the entire block between PUSH DI and POP DI
kind of resembles a separate inlined function, in accordance with Turbo
C++'s  automatic backup of the DI register, as researched in 7f971a0.

Except that it contains a loop, and Turbo C++ refuses to inline any
function with `do`, `while`, `for`, or `goto`. If it didn't, it would
have totally worked.

Also, yes, C++ class methods are treated identically in this regard.

Oh well. Shot type control functions next, finally!

Completes P0035, funded by zorg.
2019-09-24 22:04:26 +02:00
nmlgc 7f971a0d1c [Research] Find out why we can't decompile TH05's hud_bar_put()
Part of P0033, funded by zorg.
2019-09-21 14:01:51 +02:00
nmlgc 8dfc2cd535 [Research] Find out why ≥TH03 checks input twice per frame, with a 0.6ms delay
Thanks to @joncampbell123 for the tip!

Funded by zorg.
2018-09-13 18:32:24 +02:00