lolSNES 1.1

Description

lolSnes is a project I had started two years ago. I wanted to make a SNES emulator for the DS, that could render most sane games without glitches. But I followed a wrong approach with the PPU side: trying to make a line-accurate software renderer.

The DS just isn't powerful enough to handle such a renderer. That discovery pretty much shattered my motivation and the project stayed dormant for two years.

And now, for some reason, I felt like working on it again. I trashed the software PPU attempt and coded the PPU using the DS's 2D video hardware.

So far, SMW is playable, to some extent. The background layer tends to obstruct text like menus and info boxes because per-tile priorities aren't emulated yet.

You also can't get past Donut Plains 2: for some reason, the camera keeps rewinding and moving forward a bit at the start of the level, keeping you from going further. Aside from this bug, gameplay is near perfect. The game also runs at fullspeed (albeit with a speedhack).

What's in?

Main CPU: 99% -- all opcodes emulated, may miss some unimportant bits though
PPU: ~30% -- Mode 1 BG and OBJ supported, as well as some of the priority
SPC700: 80% -- most useful opcodes implemented, as well as I/O (SPC/CPU comm, timers)
DSP: 0% -- what it says. No sound yet.
Joypad input for joypad 1

Issues

There is no interface for selecting a ROM-- it is hardcoded to load snes/rom.smc
Tearing and black pixels tend to appear when backgrounds scroll, because writes to the BG scroll registers are applied directly and not synced to the DS display
CPU bugs are hidden in the main CPU core, and possibly the SPC700 core. They may bite you when you expect it the least.