https://github.com/patters-syno/msxadvance
FluBBa's MSXAdvance is a solid emulator which runs very well on GBA. There are many absolute classic shooters on the MSX1:
I forked the MSXAdvance sourcecode to hack in automatic mapper selection. I remember begging for this feature on the PocketHeaven forums back in 2006, and I seem to recall that FluBBa answered something along the lines of "it's open source, so you can add that if you really want". Well now I did
My new Python 3 builder must be used for this feature. In fact it is the builder which detects the appropriate mapper to use and records this choice in a spare byte in the ROM header for retrieval by the emulator. I implemented the same algorithm which several other MSX emulators use to scan the ROM for likely bank switch instructions and rank the observed destination addresses.
To minimise the changes needed to the emulator ARM ASM code I repurposed the upper 3 bits of the emuflags 4 byte word passed by main.c to cart.s, meaning that the spritefollow half-word within is reduced from 16 bits to 13 bits wide. The rarely-used sprite follow feature will still function but the max value is now limited to 8191.
Although MSXAdvance v0.3 and v0.4 were released, they very significantly impacted game compatibility, which is why I forked v0.2. I have updated my EZ-Flash IV exit-patched emulator collection with this development.
I never in a thousand years thought I would be able teach myself the skills to pull off this kind of hackery, but it's all thanks to open source. I have zero training nor prior experience in C, Python, nor ARM assembler other than what I've pieced together from looking at this stuff. If I can do it, so can you with some experimentation.
Enjoy!
FluBBa's MSXAdvance is a solid emulator which runs very well on GBA. There are many absolute classic shooters on the MSX1:
- Nemesis, Nemesis 2, Nemesis 3
- Salamander
- Zanac A.I.
- Twin Bee
- Parodius
- Fantasy Zone
- R-Type
I forked the MSXAdvance sourcecode to hack in automatic mapper selection. I remember begging for this feature on the PocketHeaven forums back in 2006, and I seem to recall that FluBBa answered something along the lines of "it's open source, so you can add that if you really want". Well now I did
My new Python 3 builder must be used for this feature. In fact it is the builder which detects the appropriate mapper to use and records this choice in a spare byte in the ROM header for retrieval by the emulator. I implemented the same algorithm which several other MSX emulators use to scan the ROM for likely bank switch instructions and rank the observed destination addresses.
To minimise the changes needed to the emulator ARM ASM code I repurposed the upper 3 bits of the emuflags 4 byte word passed by main.c to cart.s, meaning that the spritefollow half-word within is reduced from 16 bits to 13 bits wide. The rarely-used sprite follow feature will still function but the max value is now limited to 8191.
Although MSXAdvance v0.3 and v0.4 were released, they very significantly impacted game compatibility, which is why I forked v0.2. I have updated my EZ-Flash IV exit-patched emulator collection with this development.
I never in a thousand years thought I would be able teach myself the skills to pull off this kind of hackery, but it's all thanks to open source. I have zero training nor prior experience in C, Python, nor ARM assembler other than what I've pieced together from looking at this stuff. If I can do it, so can you with some experimentation.
Enjoy!
Last edited by patters,
