emulator: mGBA Splitscreen
type: libretro
core_classification: community_fork
source: "https://github.com/Spuds0588/mgba-splitscreen"
upstream: "https://github.com/mgba-emu/mgba"
profiled_date: "2026-10-04"
source_commit: "b66511a35873bda9c961872813e58b35543bcfc5"
core_version: "0.1.0"
display_name: "Nintendo - Game Boy Advance (mGBA Splitscreen)"
cores:
  - mgba_splitscreen
systems:
  - nintendo-gba

notes: |
  mGBA Splitscreen is a fork of mGBA that runs 2-4 linked GBA cores in a
  single libretro instance over mGBA's lockstep SIO driver. Built from
  the upstream mGBA tree with -DBUILD_LIBRETRO_SPLITSCREEN=ON
  (CMakeLists.txt:1036-1058), the fork adds the mgba-splitscreen link
  fixes (Four Swords handshake assist and a gated deadlock kick) on top
  of mGBA's library layer. The player instances live in
  src/platform/libretro-splitscreen/instances.c and reject anything that
  is not a GBA ROM (instances.c:114-119).

  The splitscreen wrapper never performs its own BIOS lookup. Each
  per-player mCore reaches mGBA's shared GBA core, which looks for
  gba_bios.bin in the system directory and uses the built-in HLE BIOS
  (src/gba/hle-bios.c) when it is missing. The core-info declares one
  optional firmware entry (gba_bios.bin) and only accepts the .gba
  extension, so GB/GBC/SGB BIOS files that upstream mGBA supports are
  unreachable here.

files:
  - name: gba_bios.bin
    system: nintendo-gba
    required: false
    hle_fallback: true
    size: 16384  # 16 KB (GBA_SIZE_BIOS)
    validation: [size]
    note: "GBA BIOS, same file upstream mGBA uses. HLE replacement built in."
    source_ref: "src/platform/libretro-splitscreen/mgba_splitscreen_libretro.info:34-37 (firmware0_desc/path/opt); src/gba/gba.c:520-551 (GBALoadBIOS, inherited from mGBA core)"