Originally ported from nullDC to libretro in commits:
2fa562db1b46c52b663b3dd4bb33a64907357458
f8eb58ac16a9e5adf662b99be5d00729264808e0
Modified for use w/ reicast per-game configuration
- Rewrite mem ops to only modify regs after exception path
- Throw & catch logic for interpreter that raises the exception
- Re-enabled some commented mmu code
Reicast doesn't support exceptions yet, so this isn't of much use now,
and is intended mostly as documentation. nullDC used some call stack
hooking magic to handle exceptions, which was never generic and clean
enough to be worth the effort to port to Reicast.
This consolidates some of the work done for TARGET_NO_NVMEM and
feat/no-direct-memmap. If nvmem is disabled at compile time or alloc
fails _nvmem_enabled() will return false. Various other fixes
and cleanups all around.