SimCity SNES Static Recomp 1.4.0

Native Windows static recompilation frontend and core for SimCity on the Super Nintendo Entertainment System.

The original game ROM is not included. Use an externally supplied, legally obtained ROM matching ROM-REQUIREMENTS.txt.

What fully static recompilation means

SimCity's executable W65C816 game instructions were analysed and translated into generated native C before the application was built. Production dispatch uses exact processor-state and program-counter contexts. It contains no general-purpose SNES CPU interpreter, runtime opcode decoder, dynamic recompiler, JIT, or automatic emulator fallback.

The audio program is static too. SimCity's exact S-SMP program-counter/opcode authority dispatches only compiled SPC700 instruction forms. Its protected-code bitmap rejects writes to statically owned driver code, and unknown execution or semantic ARAM reads stop with a diagnostic. The former emulator S-DSP runtime has been removed. A project-owned fixed 32-phase S-DSP implements register timing, BRR decoding, Gaussian interpolation, envelopes, noise, pitch modulation, echo/FIR and signed 16-bit stereo PCM at the native 32,040 Hz rate.

Game simulation, graphics, samples, music and effects are not prerecorded. They remain live state driven by the external ROM, cartridge memory, WRAM, VRAM, ARAM, controller input and SNES timing.

The complete runtime includes:

• Generated exact-context W65C816 game-code dispatch.
• Native cartridge, WRAM, bus, DMA, HDMA, controller and CPU-I/O handling.
• Native PPU registers, scanline events, rendering and framebuffer output.
• Exact rational NTSC scheduling and one guest frame per host deadline.
• Fail-closed exact-PC S-SMP AOT and project-owned 32-phase S-DSP.
• Native 32,040 Hz stereo PCM with knownness, overflow and hash diagnostics.
• Battery SRAM and deterministic snapshots including continuing audio state.
• A native accessible Win32/GDI launcher, SDL3 gamepad input and DirectSound speaker output.
• Windowed game-frame screenshots and exact fullscreen-presentation captures.

SimCity Wide Screen

Wide Screen is a game-specific core feature, not frontend stretching. The core can render 398x239: the original 256-pixel view plus 71 real city-map pixels on each side. It extends BG1/BG2 sampling, camera limits, the map cursor and building placement while keeping the HUD and toolbar anchored correctly. Title, setup, tutorial prompts, scenario selection and modal screens retain their native layout. The toolbar control is enabled by default, persists in settings.ini, and can be changed while a game is loaded.

Windows frontend and audio

Version 1.4.0 ports the current Jungle Strike frontend architecture while retaining and adapting SimCity's widescreen controls and dynamic geometry. Win32/GDI owns windows and presentation. SDL3 is used only for gamepad access.

The static core produces 32,040 Hz PCM from guest time. The host drains PCM during long guest frames, applies the selected nearest, linear or cubic-Hermite speaker resampler, and writes a DirectSound ring buffer. The playback design is based on the proven Mesen approach: cursor-derived latency measurement, pre-roll, bounded drift correction, recovery and exact rational frame pacing. The default speaker rate is 48,000 Hz. Extra forced latency is disabled by default and, when enabled, ranges from 0 to 40 ms. Host output changes never alter the core's native PCM authority.

Mesen was used as the hardware-behaviour and frontend-timing reference during development. Snes9x-derived S-SMP execution semantics remain under their original license and are restricted to the generated fail-closed SimCity AOT authority. Neither emulator is embedded as a runtime fallback.

Controls and files

The launcher provides accessible Welcome, Settings, Controls, Audio and snapshot windows. Escape switches between gameplay and the launcher; keys 1 and 2 save/load the current quick-snapshot slot. The function-key group then runs from F1 for Welcome through F2/F3 save/load snapshots, F4 Settings, F5 Controls, F6 Audio, F7 Run and F8 Screenshot. Closing Welcome or another frontend dialog restores foreground and keyboard focus to the game or the previous launcher control.

Configuration is stored in settings.ini. On a clean first launch, Welcome is shown once; closing it persists General/WelcomeShown=1, so later launches go directly to the launcher unless F1 is pressed. Saves, Screenshots and Logs are created when needed. A static-core error creates a detailed log and displays a large closeable error window rather than silently changing execution methods.

Building on Windows

Requirements:

• Windows 10 or later
• CMake 3.20 or later
• Visual Studio 2022 with Desktop development with C++
• Internet access during the first configure for pinned SDL3 gamepad source

cmake -S . -B build -G "Visual Studio 17 2022" -A x64
cmake --build build --config Release --parallel
ctest --test-dir build -C Release --output-on-failure

build\Release\Launcher.exe is the portable application. The optional SIMCITY_TEST_ROM CMake path enables the local real-ROM audio snapshot continuation test; the ROM is never copied into source or release artifacts.

Verification

The source includes contract tests for controller ordering, configuration, resampling, audio defaults, project-owned DSP phase timing, linked DSP purity and real-ROM snapshot PCM continuation. Long headless routes cover neutral execution, tutorial gameplay, HUD transitions, toolbar focus, map edges, wide-cursor travel, construction, scenarios, Freeland and all four map corners. Unknown static CPU/audio states and PCM overflow remain release failures.

Third-party notices and licenses are in THIRD-PARTY-NOTICES.txt and the corresponding source directories.