Commit Graph

6 Commits

Author SHA1 Message Date
nmlgc 50b17d640b [Reverse-engineering] [th03] SPRITE16 setup for double-buffered blitting
Part of P0114, funded by Lmocinemod.
2020-09-07 21:18:39 +02:00
nmlgc f0511221b7 [Maintenance] [th02/th03/th04/th05] Establish a common name for code segment 2
About time I finally developed this piece of tech. Towards TH05, this
segment got more and more undecompilable ASM functions mixed inbetween
C ones. Which means that pretty much all of the current ASM land
`#include`s in that segment will have to become translation units. And
we *really* don't want an additional layer of numbered, per-binary
translation units that just `#include` maybe one or two functions.

Also yeah, no _TEXT suffix, to drive home the point that this is a
"library" segment, and not really "owned" by any one file.

Part of P0113, funded by Lmocinemod.
2020-09-07 21:18:38 +02:00
nmlgc 687752160c [Maintenance] Start a new file for x86 FLAGS comparison macros
Part of P0113, funded by Lmocinemod.
2020-09-07 21:18:38 +02:00
nmlgc 368f151759 [Maintenance] Declare distinct types for screen, VRAM, and TRAM coordinates
Whew, time to look at every `int` variable we ever declared! The best
moment to do this would have been a year ago, but well, better late
than never. No need to communicate that in comments anymore.

These shouldn't be used for widths, heights, or sprite-space
coordinates. Maybe we'll cover that another time, this commit is
already large enough.

Part of P0111, funded by [Anonymous] and Blue Bolt.
2020-08-28 14:53:30 +02:00
nmlgc 43c97ccaa1 [Maintenance] Decide on __asm as the keyword for inline assembly
Which works in both Borland C++, Open Watcom, and Visual C++.

Not that we're about to port any of the games to these compilers, just
something I noticed while evaluating 32-bit compilers for ReC98's own
32-bit pipeline tools. Modders might want to look into that though,
since 100% position independence also makes it easier to change
compilers.
2020-06-21 22:18:00 +02:00
nmlgc b6e0330ff6 [Decompilation] [th03] Sprite display calls
Yes, decompilation, of something that was so obviously originally
written in ASM. We're still left with two un-decompilable instructions
here, but I'm amazed at how nicely I was able to abstract away all of
the gory register details, leading to pretty clear, readable, and dare
I say *portable* code?! Turbo C++ was once again pretty helpful here:

• `static_cast<char>(_BX) = _AL` actually compiles into `MOV BL, AL`,
  as you would have intended,
• and no-op assignments like _DI = _DI are optimized away, allowing
  us to leave them in for clarity, so that we can have all parameter
  assignments for the SPRITE16 display call in a single place.

I love this compiler.

Part of P0060, funded by Touhou Patch Center.
2019-11-28 23:14:21 +01:00