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ITotalJustice / notorious_beeg

gba emulator written in c++23
https://notorious-beeg.netlify.app/
GNU General Public License v3.0
41 stars 4 forks source link

yugioh ultimate masters 2006 - bad fifo audio in title screen #99

Closed ITotalJustice closed 2 years ago

ITotalJustice commented 2 years ago

https://user-images.githubusercontent.com/47043333/193606571-82095135-bf25-4df4-bed7-363bdd191c03.mp4

i have found 3 possible fixes:

  1. always allow changes to dma len,src,dst on dma control write, even if the channel doesnt get enabled (0 -> 1 enable transition).
  2. delay starting the dma by at least 3 cycles, relative to the current time. meaning if a store-word instruction happens, that write takes 2 cycles, then i have to delay the dma by scheduler.current_cycles + sheduler.elapsed + 3.
  3. only start an immediate dma transfer on the enable bit transitioning from 0 -> 1.

i think (1) is a false positive. 2 and 3 maybe both be correct fixes (although it only needs one of them). immediate dma is supposed to be delayed by 2-3(?) cycles.