Author Topic: Need some advice on input issues with arcade system emulation  (Read 1391 times)

Offline barbudreadmon

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Hi everyone,

I thought i would ask here, since i don't know any other people who are good at emulating arcade systems.

I've been trying to help with https://github.com/libretro/reicast-emulator lately. This is the libretro port of a dreamcast emulator, and it runs naomi/atomiswave games too. Compatibility is great (actually, greater than the standalone version), there are not that many games that won't boot or have graphical issues with the latest builds.

However, there are some issues with input :
- analogs don't work
- 2nd player doesn't work in some games

The issue with 2nd player is particularily weird, from looking at https://github.com/mamedev/mame/blob/master/src/mame/drivers/naomi.cpp i get the general idea that games like MVSC2 or DOA2 (where 2P works in this emulator) share common input mecanism with GG XX accent core and Akatsuki Blitzkampf, however 2nd player doesn't work with those 2 (and probably some other).

Any advice on what we could be overlooking would be really useful :).

Edit : i think i got a general idea of what is wrong, see https://github.com/libretro/reicast-emulator/issues/115 if you are interested or want to help.
« Last Edit: July 03, 2018, 02:13:52 pm by barbudreadmon »

Offline barbudreadmon

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Re: Need some advice on input issues with arcade system emulation
« Reply #1 on: July 05, 2018, 03:51:59 am »
I managed fixing both issues :biggrin:.

Offline dink

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Re: Need some advice on input issues with arcade system emulation
« Reply #2 on: July 05, 2018, 08:34:13 am »
Great job :)

Offline barbudreadmon

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Re: Need some advice on input issues with arcade system emulation
« Reply #3 on: July 05, 2018, 10:16:03 am »
Thanks :)

I guess no one knows about the Capcom Naomi I/O board ? It seems to be needed for 4P games.

While i didn't find anything about it in Naomi MAME driver, i see here and there that it can be used in other JVS hardware (they even mention CPS2/CPS3), so perhaps it is known under another name in MAME's sources ?

Let me know if you learn anything about it.

Offline dink

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Re: Need some advice on input issues with arcade system emulation
« Reply #4 on: July 08, 2018, 06:46:09 pm »
Unfortunately I can't find anything about the internal workings of this IO board.  :(
I wonder if you could try changing random / seemingly unused input bits until the 3p/4p inputs show activity?

Offline barbudreadmon

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Re: Need some advice on input issues with arcade system emulation
« Reply #5 on: July 09, 2018, 06:01:21 am »
I wonder if you could try changing random / seemingly unused input bits until the 3p/4p inputs show activity?
That's an interesting idea, i tried setting the bit indicating the number of player in the I/O board to 4, and ended up with this :

Inputs are broken now, but perhaps i can figure out something.

Offline barbudreadmon

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Re: Need some advice on input issues with arcade system emulation
« Reply #6 on: July 09, 2018, 06:27:36 am »
Thanks, it works, it seems i can't get the analogs working at the same time though. I guess i'll have to implement some kind of mecanism to switch between different I/O board setup. Best case scenario would be to directly load mame roms and autoconfigure this from their name (at the moment, reicast loads an arcade game from a file containing all the decrypted roms concatened, and that's kinda annoying because we can't use mame roms directly).