Big tidy-up of the codebase today, with a better delineation of the core/OSD (OS-dependent aka host platform) interface. All the Neo Geo specific code has been moved from the Xevious core to the OSD (Neo Geo in this case) files.
I've implemented the foreground tile layer on the Neo Geo, and updated the palette to support it.
I started on the transcode of the Xevious core; very early days with little more than the main loop and the function tables in RAM but it's working nicely thus far. The immediate focus is to port some code that writes to the foreground tilemap layer so I can test it, and iron out the interface.
A quick hack in the end, but managed to get this...
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| NAMCO copyright message on the foreground layer (wrong palette) |
It's a bit messy and there's still work to do but encouraging.
As with the background layer, I'm not going to replicate the mapping from video RAM to on-screen tiles; there's really no point and most if not all of the foreground video accesses are done with hard-coded screen offsets. I may be able to write a macro that converts the original offsets to linear addresses.
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