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Compatibility update: 76%!

posted by ferris on 2017.2.13 | bughunt | vertical force sign extend elusive |

This is just a small (er, maybe not that small) update to let you know that the elusive disappearing/reappearing powerups/enemies bug in Vertical Force was finally fixed, bumping up compatibility from 71% to 76%!

After many painful attempts to try and track down this bug, the answer ended up being very simple...

The bug

This bug had a number of symptoms. The most obvious was that very early in the game, powerups would disappear/reappear:

The bug

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Anyone up for some ten^_xY0mxx#C#?

posted by ferris on 2017.2.6 | bughunt | mario tennis interrupt decompression |

Note: This post was originally part of this everyweeks post, and has been edited to fit this blog.

Emulator development generally has a lot of ups and downs. Some days you'll be monstrously productive, other days it'll be a total slog to fix one or two minor bugs. This post is about one of those times :) .

Let's rewind a couple months to when I had just finished floating point op's and gamepad input (among some other things). At this point, many games still had some small graphical glitches, and a couple would even soft-lock on certain parts. Generally, debugging these weren't too bad, as it was a lot of just implementing/refining how the video hardware worked (in particular interrupt scheduling details), and a lot of games would get fixed at once and suddenly just work. There were a few cases though where games looked like they had conflicting requirements; usually this was just due to my own misunderstanding and was remedied by re-reading technical docs, but one of these in particular took a lot of effort to track down:

Mario's Tennis Glitch Edition

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