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> Your code is quite clean, but I'm not sure I'd say the rendering code is all that close to what the hardware does. OK you're right, what I really meant is th

> Your code is quite clean, but I'm not sure I'd say the rendering code is all that close to what the hardware does. OK you're right, what I really meant is that my code is a clear description of the basic hardware features and how they work, at the level of the detail discussed in the blog post being discussed (OP). As you noticed, I'm not emulating anything sub-scanline. If you look at the precise_dma_fifo branch, I've attempted some sub-scanline precision timing, while keeping the rendering at the scanline level. The result is encouraging: for instance, the 512C "your emulator suck" screen in Overdrive correctly works (at least in the PAL version IIRC). I think I hit a limit with the way timing was computed in the CPU cores I was using, and then dropped it for boredom. There were also a few regressions, visible in Overdrive itself (which is almost perfect on master, with the 512C screen being the big exception). > I think my emulator, BlastEm[0] Thanks for the reference, I'll have a look.

mikepavone 11y ago
> The result is encouraging: for instance, the 512C "your emulator suck" screen in Overdrive correctly works (at least in the PAL version IIRC). I think I hit a limit with the way timing was computed in the CPU cores I was using, and then dropped it for boredom. There were also a few regressions, visible in Overdrive itself (which is almost perfect on master, with the 512C screen being the big exception). Overdrive is tough. It has some nasty race conditions in it and of course the 512C scene requires a reasonable approximation of the reduction in sprite capacity. I don't have it working 100% myself (wanted to get some other timing related things tightened up before trying to chase down the cause of race that doesn't happen on real hardware). I commend you on getting as far as you did. The moose chase level of Mickey Mania is another good thing to check out as it also requires emulation of the sprite capacity reduction.
- giovannibajo1 11y ago
  That works as well, with a really small glitch which I'm not sure if it's present on the real hardware as well. I think my emulation of sprite limits is correct.

mikepavone 11y ago

> The result is encouraging: for instance, the 512C "your emulator suck" screen in Overdrive correctly works (at least in the PAL version IIRC). I think I hit a limit with the way timing was computed in the CPU cores I was using, and then dropped it for boredom. There were also a few regressions, visible in Overdrive itself (which is almost perfect on master, with the 512C screen being the big exception). Overdrive is tough. It has some nasty race conditions in it and of course the 512C scene requires a reasonable approximation of the reduction in sprite capacity. I don't have it working 100% myself (wanted to get some other timing related things tightened up before trying to chase down the cause of race that doesn't happen on real hardware). I commend you on getting as far as you did. The moose chase level of Mickey Mania is another good thing to check out as it also requires emulation of the sprite capacity reduction.

giovannibajo1 11y ago
That works as well, with a really small glitch which I'm not sure if it's present on the real hardware as well. I think my emulation of sprite limits is correct.