totk-pc-recomp/docs/building.md

# Building from source

Windows 10 or later, an x86-64 CPU with AVX2, and a GPU with Vulkan 1.3 and `VK_EXT_external_memory_host`. Allow about
60 GB for the work folder. Extraction wants about 55 GB free while it runs and keeps about 35 GB afterwards.

Players who only want to play can use the [installer](installer.md) instead: it builds the game on their machine
without this toolchain.

## Toolchain

Versions are the ones the build was verified with; newer patch releases are fine.

| Tool | Version | Install | Used for |
|---|---|---|---|
| MSYS2 UCRT64 | clang/lld 23.1.3 | msys2.org installer to `C:\msys64`, packages below | compiling the generated C and the runtime |
| Visual Studio Build Tools | 2026, C++ workload, Windows SDK 10.0.26100 | winget `Microsoft.VisualStudio.BuildTools` with `--add Microsoft.VisualStudio.Workload.VCTools --includeRecommended` | the linker .NET NativeAOT calls |
| .NET SDK | 10.0 | winget `Microsoft.DotNet.SDK.10` | the shader translator (`totk_xlate.exe`) |
| Vulkan SDK | 1.4.363 | winget `KhronosGroup.VulkanSDK` | validation layers, `vulkaninfo` |
| uv | 0.13 | standalone installer from astral.sh | the two Python environments |
| hactool | 1.4.0 @ `1d64a83` | `.venv\Scripts\python tools\build_hactool.py`, see below | NCA and update extraction |

MSYS2 packages, after `pacman -Syuu` (run it twice; the first pass updates the core and exits):

```sh
pacman -S --needed --noconfirm mingw-w64-ucrt-x86_64-{clang,lld,ninja,gcc,make,pkgconf,sdl3,opus,libvpx,zstd,vulkan-devel,\
vulkan-memory-allocator,vulkan-validation-layers,shaderc,spirv-tools} base-devel git unzip
```

`ffmpeg` from MSYS2 is a GPLv3 build and is never linked; the movies go through libvpx.

PATH:

- Add `C:\Program Files (x86)\Microsoft Visual Studio\Installer` to the user PATH: NativeAOT needs `vswhere.exe`, or
  the publish fails at the link step (MSB3073).
- Another `cmake` or `ninja` earlier on PATH (a 32-bit winlibs MinGW, for example) is picked up by accident. The build
  scripts call Ninja from `C:\msys64\ucrt64\bin` themselves; from a shell, put `C:\msys64\ucrt64\bin` first.

### hactool

`tools/build_hactool.py` fetches SciresM/hactool at `1d64a83` into `toolchain\src\hactool`, applies the two patches in
`tools/hactool/` and builds a static `toolchain\hactool\hactool.exe` with MSYS2 UCRT64 gcc (a few seconds):

- `portable.patch`: the parts of MacNativeGames' `build_hactool()` that run on Windows, the `MNG_TITLE_KEYS` variable and
  the two BKTR fixes in `nca.c` for the subsection table padding and the subsection layout of newer cumulative updates;
- `unicode.patch`: a manifest with `<activeCodePage>UTF-8</activeCodePage>`, so paths under a non-ASCII user profile
  reach it intact.

hactool reads `-k <prod.keys>`; MSYS2 shells set `HOME`, which hides its default key location, so pass `-k` there.

## Build

From the repository root, in PowerShell. Every step that depends on the game version takes it as `<ver>`: `v143` for
1.4.3 or `v121` for 1.2.1. The tools default to `v121` when `--version` is left out. Saves load on either version.

1. Python environments (once). `.venv` runs the lifter and the build; `.venv-py314` runs the extraction scripts, which
   need the stdlib `compression.zstd` of Python 3.14:

   ```powershell
   uv venv --python 3.12 .venv
   uv pip install --python .venv/Scripts/python.exe -r tools/requirements.txt
   uv venv --python 3.14 .venv-py314
   uv pip install --python .venv-py314/Scripts/python.exe -r tools/requirements-py314.txt
   ```

2. Copy `config.example.toml` to `config.local.toml` and set the paths to your base game, the update and your console's
   keys file. `config.local.toml` is ignored by git. The tools read the keys file themselves.

3. Extract and verify. This writes `build\extracted\v0` (1.0.0) and `build\extracted\<ver>` for each update in
   `updates`, identified by its hash; a hash mismatch stops the run:

   ```powershell
   .venv-py314\Scripts\python tools\extract.py
   ```

4. Shader translator (once; no game files). This publishes `build\xlate\totk_xlate.exe`:

   ```powershell
   .venv\Scripts\python tools\build_xlate.py
   ```

5. Lift the modules to C, write the RomFS half of the frame-rate patches, then compile and link `build\<ver>\totk.exe`:

   ```powershell
   .venv\Scripts\python recomp\gen.py --exefs build\extracted\<ver>\exefs --out generated\<ver> --patches recomp\patches-<ver>.txt
   .venv-py314\Scripts\python tools\make_romfs_patches.py --version <ver>
   .venv\Scripts\python tools\build_game.py --version <ver>
   ```

   Lifting takes about 15 s, a clean compile about 200 s on 24 threads; later builds recompile only what changed.
   A compiler cache in front of clang shortens it further: with `SCCACHE` set to an sccache executable, `build_game.py`
   writes it into the ninja file ahead of `cc`, and every lift rewrites the generated chunks with the same contents, so
   a second build of the same version hits all of their objects:

   ```powershell
   $env:SCCACHE = "path\to\sccache.exe"
   .venv\Scripts\python tools\build_game.py --version <ver>
   ```
   `--patches` builds in the frame-rate, resolution and other patch sets, switchable at run time. The link copies
   `SDL3.dll`, `libiconv-2.dll` and `libopus-0.dll` next to the exe.
   For Xbox button prompts, run `make_romfs_patches.py` once more with `--xbox-prompts`: it writes
   `build\<ver>\romfs-patches-xbox` ([controls.md](controls.md), "Xbox button prompts"); `build_game.py` copies it next
   to `totk.exe` like `romfs-patches`.

6. Prepare the shaders (once per build folder and translator). It needs `refs\MacNativeGames` (`tools\fetch_refs.sh`)
   for the shared shader list:

   ```powershell
   .venv-py314\Scripts\python tools\prepare_shaders.py build\<ver> --version <ver>
   ```

   Without this step the first launch compiles shaders and pipelines during play and stutters until the caches fill.
   The AMD driver keeps its pipeline cache per exe path and holds a limited amount: preparing another build folder can
   evict this one's. `totk.exe --warm-shaders` rebuilds it from the shader cache.

7. Run. The game pauses while its window is out of focus, as it does on the Switch when Home is pressed;
   `assume_focus = 1` in `totk.ini`, or the Game tab, keeps it running in another window.

   ```powershell
   build\<ver>\totk.exe
   ```

Settings live in `totk.ini` next to `totk.exe` ([totk.ini.example](../totk.ini.example) lists them). Saves go to
`build\profile` for `v121` and `build\profile-<ver>` for other versions (`build_game.py --profile` changes it).

### Portable folder

`.venv\Scripts\python tools\package_build.py --version <ver>` writes `build\<ver>-portable`, which runs on another of
your machines without MSYS2, Python or .NET. `romfs.bin` stays out unless you pass `--with-romfs`; otherwise put it in
`romfs\` next to the exe or point `TOTK_ROMFS` at its folder. Run `totk.exe --prepare-shaders` once in the copied
folder. The folder holds code and data derived from your game: for your own machines only.

## Checks

Before a commit:

- `python tools/check_content.py --staged`: nothing game-derived is staged. CI runs the same check;
  `git config core.hooksPath .githooks` runs it before each local commit.
- `build\<ver>\totk.exe --selftest`: layout, dispatch table and host-function registry, without game files.

The lifter (`recomp/`) and the CPU headers (`runtime/cpu.h`, `runtime/simd.h`) are checked against Unicorn. Every lifter
change passes these, all run with `.venv`:

| Test | Checks | Game files |
|---|---|---|
| `tests\diff\lift.py` | instructions sampled from the extracted modules; `--coverage` lists every word the lifter rejects or traps | yes |
| `tests\diff\simd.py` | the whole FP/SIMD encoding space | no |
| `tests\diff\atomic.py` | exclusive load/store sequences and ARMv8.1 atomics | no |
| `tests\diff\func.py` | whole functions as the generator emits them, loops, jump tables and calls included (calls go to a stub that checks the registers at the call) | yes |
| `tests\flags_check.py` | the function-local flag helpers of `runtime\cpu.h` against its packed ones | no |
| `tests\excl_mt.py` | the exclusive monitor helpers under contention and ABA, on several threads | no |
| `tests\jumptables_check.py` | `recomp/jumptables.py` against a Unicorn oracle; must report 0 disagreements, on 1.4.3 too | yes |

Runtime probes, each a mode of `totk.exe` (the list is at the top of `runtime/main.c`): `--probe-kernel`,
`--probe-vkexec`, `--probe-nvn-tex` and `--probe-shader` cover most runtime changes.

Shaders: `.venv-py314\Scripts\python tools\shader_census.py --version <ver> --translate` extracts every Maxwell shader
to `build\<ver>\shaders\` and runs it through the translator and `spirv-val`; failure groups go to `failures.txt`.
`tools\xlate_smoke.py` checks the translator alone, without game files.

## Reverse engineering (optional)

- Ghidra 12.1.2 with Adubbz's Ghidra-Switch-Loader in `toolchain\ghidra\` (JDK 21) opens the game modules (NSO).
- `tools\fetch_refs.sh` clones the upstream projects this port builds on into `refs\`, read-only.