James Pond 3 Recomp

James Pond 3 — Static Recompilation

A source-level static recompilation of James Pond 3: Operation Starfish (Millennium / Electronic Arts, Sega Genesis/Mega Drive, 1993) built on mstan/segagenesisrecomp.

The original 68000 ROM is translated to C at build time; the runner supplies the clean-room Genesis hardware (VDP, bus, Z80, YM2612, SN76489) and SDL2 host layer. No emulator core is linked into the game executable.

ROM

Use the No-Intro dump James Pond 3 (USA, Europe).md (2 MB):

Size	2,097,152 bytes
CRC32	0x26F64B2A
SHA-256	8f52e27945b96d6c37fda28c44d39d65d805cc0b58332f9b4a2eb26dff540d29
Header	JAMES POND III, serial GM T-50646 -00
Regions	U / E / J (ROM contains both 50 Hz and 60 Hz code paths)

The ROM is not committed to this repository. Place it at the project root with the exact filename above, or create the expected link:

ln -sf '../James Pond 3 (USA, Europe).md' game/jp3.md

Build

Requirements: CMake ≥ 3.16, Ninja or Make, a C11/C++17 toolchain, SDL2 development files.

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build -j"$(nproc)"

The build regenerates the 68K→C translation from the ROM and game/game.toml as part of the normal build (output under build/generated/jp3/). Generated C is deliberately not tracked.

Run

./build/JamesPond3Recomp game/jp3.md

Useful headless/automation flags (shared runner):

# Run 600 frames, hash the framebuffer every 60, write a PNG at exit
SDL_AUDIODRIVER=dummy SDL_VIDEODRIVER=dummy \
GENESIS_SCREENSHOT_AT_EXIT=/tmp/jp3.png \
./build/JamesPond3Recomp game/jp3.md --max-frames 600 --turbo --hash-frames 60

The runner writes runtime evidence next to the executable: dispatch_misses.toml, floor_coverage.toml, floor_unsafe.toml, and interior_label_misses.toml. Addresses recorded there are audited and, once confirmed against the ROM, promoted into game/game.toml.

Repeatable probes live in tools/:

cd build
# Boot through the title/menu into Garden of Edam; writes gameplay_*.png
SDL_AUDIODRIVER=dummy SDL_VIDEODRIVER=dummy \
  ./JamesPond3Recomp jp3.md --turbo --input-script ../tools/gameplay_probe.input

# Assert the ROM selected NTSC (60 Hz): $FFFD19=0, $FFFD18=$FF
SDL_AUDIODRIVER=dummy SDL_VIDEODRIVER=dummy \
  ./JamesPond3Recomp jp3.md --turbo --input-script ../tools/ntsc_check.input

# Exercise movement, jumping, and tongue attacks in Garden of Edam
SDL_AUDIODRIVER=dummy SDL_VIDEODRIVER=dummy \
  ./JamesPond3Recomp jp3.md --turbo --input-script ../tools/move_attack_probe.input

# Jump repeatedly while moving right (first-platform regression probe)
SDL_AUDIODRIVER=dummy SDL_VIDEODRIVER=dummy \
  ./JamesPond3Recomp jp3.md --turbo --input-script ../tools/jump_probe.input

Trainer

Press T while playing to open the trainer menu. Up/Down select, Enter or Space toggles, T or Esc closes. The toggles are infinite lives, infinite health (also grants the maximum five health), infinite frog lives, infinite jumps (each press of the jump button in mid-air boosts you upward again), infinite jetpack fuel (hold jump with the jetpack equipped to fly without the tank draining) and infinite invulnerability (the damage immunity you get at level start and after a hit never expires), "exit level from pause" (the pause menu's B command normally only works after the level has been completed) and "ammo type override". Left/Right on the AMMO TYPE row pick the gun's ammo (apple, strawberry, orange, pudding or cupcake); while the override is on the gun always fires the chosen type, and with it off the gun keeps whatever ammo the game gives you. They stay enabled across levels and save loads until you quit.

Save states

Shift+F1..F9 saves, F1..F9 loads; on a gamepad, LB saves slot 1 and RB loads it. A save contains the portable CPU/RAM/VDP image plus an embedded in-process rollback snapshot of the suspended game fiber. Loading it in the session that wrote it restores the exact yield point — same game mode, frame position, scheduler state and pending work — so repeated loads are deterministic. Saves from an older build may not work as intended.