First, I fixed some issues with the mode7 / scroll regs thanks to info from anomie. Qwertie's mode7 demo runs without modification now. Next, I fixed a small glitch with tiles getting cut off on the right edge of the screen, fixes some flickering on the edges in Zelda 3. Finally, I added tile caching to all 4 BG layers. It didn't really increase speed by much (~10%), and upped the RAM requirements by 1.2mb... I left the old code in case I need to fall back on it. My only guess (hope) is that the bottleneck lies somewhere else...
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Had a small glitch in the OAM $2102/$2103 register settings, fixed that and now both Zelda 3 and Super Mario World always show sprites perfectly. The only error to my knowledge in the below screenshots is that the large version of the mario sprite in the third pic is not shown at the top left of the screen. Which could be because I have no mosaic support. But at any rate, both games should be completely playable now, albeit very slowly. I tried to speed up things by caching some stuff in the PPU, but I couldn't find a nice way to implement it that would result in a significant speed increase. Oh yeah, Zelda won't follow you in Zelda 3, but you can just go to the throne room and push the picture to the right yourself, and she'll appear when you reach the sanctuary.
I also updated the debugger, it uses a smaller font, which is a bit harder to read, but saves a lot of screen space. This will definately be needed when I add in more of the debugging windows in the future, so it's better to get used to it now than later.
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Added SRAM support. It's compatible with other emulators. It maps both the LoROM SRAM between $700000-$7dffff, and HiROM SRAM between $3n6000-$3n7fff (where n = 0 - f).
Modified the screen to redraw at scanline 224, instead of 0. Fixes some flickering between screens in some games.
Moved the lighting adjustment code ($2100 bits 0-3) directly into the PPU, rather than outside in the platform-specific code. This is because games have the ability to adjust this value per scanline. Also allowed the games to control the background enable ($2100 bit 7) flag per scanline now. This allowed Bahamut Lagoon's dragon intro to work.
I then added mode2 support, so now all that's missing is modes 5 and 6 (interlaced).
I also created an easy #define to select between the public domain mode7 code I wrote, and the snes9x mode7 code. I'll go through one of these days and rewrite the snes9x code in a clean environment (e.g. without using the current mode7 file as a reference) to avoid the issue altogether, but for now... the snes9x code is twice as fast, and that's good enough for me.
Lastly, I also added in a trace checkbox to enable tracing. As such, the zip file of my work up now has debug mode enabled by default. I really need an overhaul of the gui implementation, and a configuration file. I have a very nice string library system (that I wrote myself) that I would love to take advantage of in this project.
Here's some screenshots of the dragon intro. Lots of HDMA here, showing that I pretty much have HDMA down, now. I remember zsnes used to have a problem with these screens, and had to do something with an HDMA hack to get around it. They figured out what the problem was, eventually. I was actually quite surprised my emulator does not suffer from this same problem. Lucky for me, as they never did mention what the problem was to begin with. The HDMA is technically drawing too soon (at the start of the scanline instead of the end) which probably messes things up a bit, and I'm guessing the scroll registers are screwing up in one or two of the below pics. No mosaic support either.
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byuu