spaceship

First Gameboy DMG Homebrew game

Building

wla-gb game.asm
wla-link game.link game.gb

Instructions

D-PAD to move around, Push A to spawn bullets. That's about it...

Post-Mortem

The code is kind of a mess and it gets hard to extend and work with. Here are some reasons I suppose this is the case.

Stylistic

• We're not programming BASIC anymore. We're allowed to have mixed casing and this makes it so that words in the labels don't blend as much together.
• Inline comments should be preferred so that the Instructions stream smoother than they actually did.
• A macro for each RST routine would've been very helpful. It gets really confusing really quickly what RST routine does what without being able to see the names I've assigned them.

Technical

• Using an SOA-style for storing the positions and OAM addrs of entities was a good idea. It made both of them much easier to index individually. Perhaps I should've also split up positions into X and Y arrays.
• Arrays should be 256-byte aligned when possible because this makes indexing easier as the scaling can be done in A which can then be loaded immediately into the low byte. This also removes the need for any additions.
• Arrays should not cross 256-byte pages when possible. Similar reasoning to being 256-byte aligned.
• Common aggregates like position in this game should be accessed by function so that scaling the index doesn't have to be inlined every time.
• Common calling conventions should be defined instead of having ad-hoc ones like I did here. The exception is RST routines. They're special and few enough to justify the assumptions I made for them.
  • Because deep call stacks aren't common, a good one is to assume that all registers are volatile and that
  • arguments are passed into A, HL, DE, BC
• Symbol files would have been extremely helpful. I don't know how to port them from WLA to BGB emulator. I really should learn this.
• WLA might have a way to eliminate some of the magic numbers I have. IDK. I should learn the assembler.
  • I could also consider maintaining the Z80 target for GNU binutils in my free time. These are build tools I know. The problem is that such tools aren't common to emulators so they'd likely be harder to debug... Similar case with 65XX targets.