Boom! Clever segment renaming allows us to link the same .OBJ into 12
binaries.
(Well, 10 for now, due to alignment issues in TH04's OP.EXE and
MAINE.EXE.)
Part of P0138, funded by [Anonymous] and Blue Bolt.
So, we have a problem. The ridiculously optimized graph_putsa_fx() used
in TH04 and TH05 swaps out the target of two CALL instructions at
run-time… because there *really* wasn't any free register left for an
indirect CALL, eh? Therefore, the necessary relative addresses have to
be calculated at assembly time, by subtracting the target function
label from the call site label.
Unfortunately, the resulting values are stored in the .DATA segment,
which we can't move out right now. Declaring the labels as EXTERN
wouldn't work either, since the linker can't do fancy arithmetic and is
limited to simply replacing address placeholders with one single
address. This is explained pretty well at:
http://computer-programming-forum.com/46-asm/48f3d4a463bb38d1.htm
Which means we're stuck, and can't separate out this function for the
foreseeable future.
So, time to approach the SHARED segment from the top instead, to at
least get everything around graph_putsa_fx() done now. 🤷
vram_planes_set() is the first common function there. But since it was
introduced in TH01, we've got some maintenance to do for that game
first…
Part of P0138, funded by [Anonymous] and Blue Bolt.
It's not necessary for assigning `__seg` pointers to `far` ones, which
might even remove the <dos.h> dependency in some translation units.
Part of P0134, funded by [Anonymous].
Leading to slight complications in TH02's Music Room and shot type
selection menus. Thought about leaving those in C for a while, but I
still think it's worth it for the consistency we get with the VRAM
offset functions. Also, we'll have similar code for the main menus of
later games, and I'll surely won't be using C++ when starting out with
these.
Part of P0105, funded by Yanga.
Which repurpose the .PTN image slots to store the background of
frequently updated VRAM sections, like all the numbers in the HUD.
Future games would simply use the text RAM and gaiji for numbers. Which
would have worked just fine for TH01 as well (especially since all the
functions we've seen so far are aligned to the 8-pixel byte grid), but
it looks as if ZUN simply wasn't aware of gaiji during the development
of TH01.
Part of P0083, funded by Yanga.
nmlgc