71bbd10ad0
The Tengen 800032 (RAMBO-1) IRQ counter on real hardware auto-reloads from its latch when it would otherwise underflow, and the IRQ triggers when the counter REACHES zero (going from 1 to 0) rather than on the underflow step that follows. Upstream's earlier model triggered on underflow (count 0 -> 0xFF) and then continued decrementing through 0xFE, 0xFD, ... until the game wrote a reload register ($C000/$C001/$E000/$E001 with rmode==1). For titles that don't write the reload register on every IRQ - Skull & Crossbones in 2-player mode is the documented case (libretro docs Compatibility entry), but Hard Drivin', Klax, Rolling Thunder, Road Runner, Xenophobe etc. all use the same mapper - subsequent IRQs after the first underflow are silently swallowed, displacing the status-bar split point and producing the screen-shake / glitch reported in #544. Backport reference: negativeExponent's libretro-fceumm_next commit 7f277a8 ("Cleanup mapper 64/158") plus the Mesen RAMBO-1 model. This patch is the minimal algorithmic delta against upstream: - RAMBO1IRQHook (CPU-cycle mode, IRQmode==1): trigger on IRQCount reaching 0, auto-reload from IRQLatch on the next clock after the trigger. - RAMBO1HBHook (scanline / A12-approximation mode, IRQmode==0): same change. rmode is still set on IRQ fire so existing register-reload semantics on $C000/$C001/$E000/$E001 are preserved bit-for-bit - the writes do exactly what they did before, the only behaviour change is what the IRQ hook itself does between writes. - IRQLatch == 0 edge case handled (reload yields 0, which is the reach-0 trigger condition, so IRQs fire on every clock - the documented hardware behaviour at latch=0). Crucially, this does NOT change: - SFORMAT chunk layout (REGS/CMDR/MIRR/RMOD/IRQM/IRQC/IRQA/IRQL chunks all still present, same byte sizes, same order). Old savestates continue to load correctly. - The write-side dispatch (RAMBO1_Write) for $A000, $8000, $8001, $C000, $C001, $E000, $E001 - all behave exactly as before, including the rmode==1 conditional reload. - Mapper 158 (TENGEN 800037, Alien Syndrome Unl) wiring - it shares the RAMBO1 IRQ hook and gets the same fix for free. - PRG/CHR/mirroring sync logic. - Power-on and StateRestore behaviour. Build verified: tengen.c -O2 / -O3 / aarch64 -O2 clean.
FCE Ultra mappers modified
FCEU "mappers modified" is an unofficial build of FCEU Ultra by CaH4e3, which supports a lot of new mappers including some obscure mappers such as one for unlicensed NES ROM's.
Sequential targets Light Guns support added
Support for Sequential targets Light Guns has been added. "Gun Aux A" serves as light sensor logic input.