214c77052e
The libretro driver's per-frame turbo toggle counters (turbo_button_toggle[MAX_PLAYERS][TURBO_BUTTONS]) are advanced in the input poll while the turbo button is held, and the modular phase of that counter drives when the underlying NES button fires inside the turbo cycle. These counters were module-level state with no savestate involvement: not serialized, not reset on retro_reset, not reset on retro_unserialize. In netplay, the host and client tick this counter independently from their own local input. When the host snapshots state and ships it to the client to align them, the chunk parser restores every NES hardware register, mapper register, and core-level setting - but both ends' turbo counters keep whatever local phase they had. As long as the turbo button stays held, the two ends compute different turbo-fired-this-frame bits, which produce different NES input sequences, which produce divergent game state. Issue #75 has been open on this since 2017. Two-line fix: 1. After FCEUI_LoadGame returns successfully in retro_load_game, the core has just finished populating SFMDATA[] with all mapper chunks via AddExState. Append one more chunk (AddExState(turbo_button_toggle, sizeof(...), 0, "TBTG")) so the toggle counters save and restore alongside everything else. The "TBTG" tag is unused by any known mapper. ReadStateChunk's skip-unknown logic handles older states that predate this chunk - the array stays at the value retro_reset zero-initialised it to, which is now the correct post-load default. 2. memset turbo_button_toggle to zero in retro_reset. Without this, a held turbo button would resume mid-cycle on Reset and produce a different first-frame NES input bit than a fresh boot - small but observably non-deterministic, and the same surface that #75 targets. Verified by inspecting the serialized state binary: - Pre-fix: no TBTG chunk present. - Post-fix, after 5 frames of held turbo with delay=3: TBTG @ offset 5624, size 8, payload 02 00 00 00 00 00 00 00 (counter for player-0 turbo-A = 2, as expected from 5 increments mod (delay+1) = mod 4) ReadStateChunk + CheckS handle the restore via the standard tag-match path (state.c:277), which is bit-for-bit identical to how every mapper chunk gets reloaded. No additional load-side wiring needed.
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.