Download NVIDIA DLSS in the setup for RTX GPUs

dlaa and the DLSS modes need nvngx_dlss.dll next to totk.exe, which the release does not ship, so most players
never had DLSS. A new setup step after prepare downloads NVIDIA's own copy from the DLSS SDK repository
(github.com/NVIDIA/DLSS, tag v310.9.1, NVIDIA RTX SDK license) and checks its size and SHA-256.

The window has a tick box for it, on by default and named with its source and licence; the CLI takes --dlss. The
step runs on Windows with an NVIDIA RTX GPU (the host check's Vulkan devices), keeps a DLSS library the player
already put there, and on a failed download warns and lets the game run without DLSS; the next setup run tries
again. Texts in English, Russian, Brazilian Portuguese and Simplified Chinese, docs/installer.md step 7, tests in
tests/installer_test.py (DlssTest, with a file: URL).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/installer.md

@@ -23,6 +23,7 @@ The install folder (`main.c` `portable_paths()` reads this layout; it stays port
 ```
 <install folder>/
   totk.exe, SDL3.dll, libopus-0.dll, totk_xlate.exe
+  nvngx_dlss.dll                 NVIDIA DLSS, downloaded by the setup's DLSS step when the player keeps it ticked
   totk.ini                       language; the other keys as commented defaults (totk.ini.example)
   exefs/, romfs/                 extracted from the player's files
   shared-fonts/                  the Switch system fonts, with Chinese, Korean or Traditional Chinese text
@@ -72,7 +73,13 @@ loads the saves 1.4.3 wrote.
    When the graphics driver crashes while building the shaders, `prepare_shaders.py` runs that part again without the
    variants it was building ([building.md](building.md), step 6), and the setup finishes with a warning that names how
    many were left out.
-7. **Clean up** the temp folder, except the generated C and the objects (about 1.3 GB), and write
+7. **DLSS** (the window's tick box, on by default, or `--dlss`; Windows with an NVIDIA RTX GPU): download
+   `nvngx_dlss.dll` from NVIDIA's own DLSS SDK repository (github.com/NVIDIA/DLSS, a pinned tag, NVIDIA RTX SDK
+   license) into the install folder and check its size and SHA-256 (`steps.py`, `Dlss`). The release does not ship
+   the library; NGX loads it from the folder of totk.exe for `dlaa` and the DLSS modes. A DLSS library already in the
+   folder (a newer one the player put there) is kept. Without an RTX GPU the step warns and does nothing; a failed
+   download warns, the game runs without DLSS, and the next run of the setup tries again.
+8. **Clean up** the temp folder, except the generated C and the objects (about 1.3 GB), and write
    `build-cache/rebuild.txt` in the install folder.
 
 A cancelled or failed setup resumes from the last finished step (`totk-install.json`).

installer/__init__.py

@@ -4,7 +4,7 @@
                         [--temp DIR]
 
 Modules: layout (where the bundled tools are, release or repository), events (JSON progress on stdout and the log
-file), state (totk-install.json), runner (which steps run: resume and update), steps (the seven steps), ini (totk.ini),
+file), state (totk-install.json), runner (which steps run: resume and update), steps (the eight steps), ini (totk.ini),
 cli (the command line). text/en.json holds the English text of every message id the events carry.
 
 Standard library only, apart from what the extraction tools import (cryptography). Runs on Python 3.14.

installer/cli.py

@@ -1,5 +1,5 @@
 """Command line: python -m installer --base FILE --update FILE --keys FILE --lang CODE --dest DIR [--firmware DIR]
-                                     [--root DIR] [--temp DIR] [--verify]
+                                     [--root DIR] [--temp DIR] [--verify] [--dlss]
 
 A first install needs every option. --firmware names the Switch firmware folder (an unpacked firmware or an emulator's
 Contents/registered); the setup extracts the system shared fonts from it when the language is Chinese, Korean or
@@ -7,6 +7,9 @@ Traditional Chinese. On a folder with totk-install.json (resume after a cancel o
 release) only --dest is needed: --lang defaults to the recorded language, and the game files are needed only when the
 extraction has to run again. Prints JSON events on stdout (events.py). Exit code: 0 done, 1 failed, 2 bad command
 line, 3 cancelled (Ctrl+C or Ctrl+Break).
+
+--dlss downloads NVIDIA's DLSS library (nvngx_dlss.dll) from NVIDIA's DLSS SDK repository into the install folder on
+Windows with an NVIDIA RTX GPU (steps.py, Dlss).
 """
 import argparse
 import hashlib
@@ -58,6 +61,8 @@ def main(argv=None):
     ap.add_argument('--temp', type=Path, help='temp folder (default: temp/ of the release on Windows, .setup-temp in '
                                               'the install folder on Linux, build/install-temp in a repository)')
     ap.add_argument('--verify', action='store_true', help='hash every kept file, also those this release made')
+    ap.add_argument('--dlss', action='store_true', help="download NVIDIA's nvngx_dlss.dll (NVIDIA RTX SDK license) next "
+                                                      'to the game, for dlaa and the DLSS modes')
     args = ap.parse_args(argv)
 
     # The window cancels with Ctrl+Break to the installer's process group (CREATE_NEW_PROCESS_GROUP), which also reaches

installer/gui.py

@@ -227,6 +227,12 @@ class App:
         self.button(grid, 'ui.browse', self.pick_dest).grid(row=i + 1, column=2, padx=(8, 0))
         self.label(f, 'ui.compressed_help', wraplength=620, justify='left').pack(anchor='w', pady=(8, 0))
         self.label(f, 'ui.firmware_help', wraplength=620, justify='left').pack(anchor='w', pady=(8, 0))
+        # On by default and named with its source and licence: the player sees what is downloaded and can untick it
+        self.dlss_var = tk.BooleanVar(value=True)
+        dlss = ttk.Checkbutton(f, variable=self.dlss_var)
+        self.bind_text(dlss, 'text', 'ui.dlss')
+        dlss.pack(anchor='w', pady=(8, 0))
+        self.label(f, 'ui.dlss_help', wraplength=620, justify='left').pack(anchor='w', padx=(22, 0))
         self.update_hint = ttk.Label(f, wraplength=620, justify='left')
         self.update_hint.pack(anchor='w', pady=(8, 0))
         self.form_error = ttk.Label(f, style='Err.TLabel', wraplength=620, justify='left')
@@ -289,7 +295,8 @@ class App:
 
     def form(self):
         return Form(base=self.vars['base'].get(), update=self.vars['update'].get(), keys=self.vars['keys'].get(),
-                    firmware=self.vars['firmware'].get(), lang=self.selected_lang(), dest=self.vars['dest'].get())
+                    firmware=self.vars['firmware'].get(), lang=self.selected_lang(), dest=self.vars['dest'].get(),
+                    dlss=self.dlss_var.get())
 
     def refresh_form(self):
         form = self.form()
@@ -537,7 +544,7 @@ class App:
 # ---- self test ---------------------------------------------------------------------------------------------------
 
 SAMPLE_START = {'type': 'start', 'release': 'selftest', 'mode': 'install', 'dest': 'Z:/selftest/TotK', 'log': 'D:\\log.txt',
-                'steps': ['check', 'fonts', 'extract', 'lift', 'compile', 'prepare', 'cleanup']}
+                'steps': ['check', 'fonts', 'extract', 'lift', 'compile', 'prepare', 'dlss', 'cleanup']}
 SAMPLE_RUN = [
     SAMPLE_START,
     {'type': 'plan', 'run': ['check', 'fonts', 'extract'], 'skip': {}},

installer/guilogic.py

@@ -27,7 +27,7 @@ TEXT = Path(__file__).resolve().parent / 'text'
 UI_LANGUAGES = ('en', 'ru', 'pt-BR', 'zh-Hans')
 # what the language switch in the window's corner shows for each
 UI_LANGUAGE_LABELS = {'en': 'English', 'ru': 'Русский', 'pt-BR': 'Português (Brasil)', 'zh-Hans': '简体中文'}
-STEP_ORDER = ('check', 'fonts', 'extract', 'lift', 'compile', 'prepare', 'cleanup')
+STEP_ORDER = ('check', 'fonts', 'extract', 'lift', 'compile', 'prepare', 'dlss', 'cleanup')
 # message parameter -> catalog id prefix of the names that replace its raw values
 PARAM_NAMES = {'lang': 'lang.', 'known': 'lang.', 'step': 'step.', 'input': 'param.input.'}
 LANG_RU = 0x19   # primary language id of Russian in a Windows LANGID
@@ -137,6 +137,7 @@ class Form:
     firmware: str = ''
     lang: str = ''
     dest: str = ''
+    dlss: bool = False
 
     def installed_state(self):
         """The recorded state of the install folder (totk-install.json), or None. Never raises."""
@@ -187,6 +188,8 @@ class Form:
             cmd += ['--temp', str(temp)]
         if verify_hashes:
             cmd.append('--verify')
+        if self.dlss:
+            cmd.append('--dlss')
         return cmd
 
 

installer/steps.py

@@ -1,4 +1,4 @@
-"""The seven setup steps of docs/installer.md: check, fonts, extract, lift, compile, prepare, cleanup.
+"""The eight setup steps of docs/installer.md: check, fonts, extract, lift, compile, prepare, dlss, cleanup.
 
 Extraction runs in this process through tools/extract.py (the package's sibling tools/, which ships with it); fonts
 runs the vendored extract_shared_fonts.py on the firmware folder; lift, compile and prepare run the bundled Python on
@@ -7,7 +7,7 @@ recomp/gen.py, tools/build_game.py, tools/make_romfs_patches.py and tools/prepar
 with the bundled clang (hostcheck.c).
 
 Install folder: exefs/, romfs/ (romfs.bin, index.json), profile/, shared-fonts/ (Chinese and Korean text), totk.exe
-and its DLLs, romfs-index.bin, romfs-patches/, romfs-patches-xbox/, romfs-patches-xbox-label/, totk_xlate.exe, the
+and its DLLs, nvngx_dlss.dll (with --dlss), romfs-index.bin, romfs-patches/, romfs-patches-xbox/, romfs-patches-xbox-label/, totk_xlate.exe, the
 shader state of totk.exe --prepare-shaders, totk.ini, totk-install.json.
 Temp folder (<temp>/<dest name>-<hash>): check/ (ExeFS of both inputs, the host check), unpacked/ (the NSP of an NSZ
 or XCZ input until the extraction is done), gen/ (C), build/ (objects), logs/. The cleanup keeps gen/, build/ and
@@ -29,6 +29,7 @@ import subprocess
 import sys
 import threading
 import time
+import urllib.request
 from pathlib import Path
 
 from . import ini
@@ -1114,7 +1115,79 @@ class Prepare(Step):
         return {'xlate_sha256': file_sha256(xlate)}
 
 
-# ---- 7. clean up
+# ---- 7. NVIDIA DLSS
+
+# NVIDIA's DLSS library, which NGX loads from the folder of totk.exe (runtime/vk_dlaa.c). The setup does not ship it:
+# with --dlss it downloads NVIDIA's own copy from the DLSS SDK repository (NVIDIA RTX SDK license) at a pinned tag and
+# checks its hash. The game runs without it; dlaa and the DLSS modes then do nothing.
+DLSS_DLL = 'nvngx_dlss.dll'
+DLSS_VERSION = '310.9.1'
+DLSS_URL = f'https://raw.githubusercontent.com/NVIDIA/DLSS/v{DLSS_VERSION}/lib/Windows_x86_64/rel/{DLSS_DLL}'
+DLSS_SIZE = 58956912
+DLSS_SHA256 = '3975567b8943c53acce397f2b72380092f84f162d00b0d2c7d08a1025c563983'
+DLSS_LICENSE = 'https://github.com/NVIDIA/DLSS/blob/main/LICENSE.txt'
+
+
+def nvidia_rtx(host):
+    """An NVIDIA RTX GPU among the host check's Vulkan devices: the GPUs DLSS runs on."""
+    return any('NVIDIA' in d['name'].upper() and 'RTX' in d['name'].upper() for d in (host or {}).get('devices', []))
+
+
+class Dlss(Step):
+    """With --dlss on Windows and an NVIDIA RTX GPU: nvngx_dlss.dll next to totk.exe. A DLSS library the player put
+    there (another version) is kept. A failed download warns and is tried again on the next run; the game runs
+    without it."""
+
+    id = 'dlss'
+
+    def key(self, ctx):
+        if not getattr(ctx.options, 'dlss', False):
+            return fingerprint('dlss-1', 'off')
+        return fingerprint('dlss-1', DLSS_VERSION, DLSS_SHA256)
+
+    def current(self, ctx, record):
+        if record.get('failed'):
+            return False
+        return not record.get('installed') or (ctx.dest / DLSS_DLL).is_file()
+
+    def run(self, ctx):
+        if not getattr(ctx.options, 'dlss', False):
+            return {}
+        if os.name != 'nt':
+            return {'skipped': 'not_windows'}
+        if not nvidia_rtx(getattr(ctx, 'host', None)):
+            ctx.reporter.warning('warn.dlss_no_rtx')
+            return {'skipped': 'no_rtx'}
+        rep, target = ctx.reporter, ctx.dest / DLSS_DLL
+        if target.is_file():
+            if file_sha256(target) == DLSS_SHA256:
+                return {'installed': DLSS_VERSION}
+            rep.warning('warn.dlss_kept', path=str(target))
+            return {'kept': True}
+        part = ctx.temp / (DLSS_DLL + '.part')
+        rep.progress('dlss', 'download', 0, DLSS_SIZE, 'bytes', force=True)
+        rep.log(f'dlss: {DLSS_URL} (license {DLSS_LICENSE})')
+        try:
+            part.parent.mkdir(parents=True, exist_ok=True)
+            h, done = hashlib.sha256(), 0
+            with urllib.request.urlopen(DLSS_URL, timeout=60) as r, open(part, 'wb') as f:
+                while block := r.read(1 << 20):
+                    f.write(block)
+                    h.update(block)
+                    done += len(block)
+                    rep.progress('dlss', 'download', min(done, DLSS_SIZE), DLSS_SIZE, 'bytes')
+            if done != DLSS_SIZE or h.hexdigest() != DLSS_SHA256:
+                raise OSError(f'{done} bytes, SHA-256 {h.hexdigest()[:16]}, not the expected file')
+            replace_file(part, target)
+            remove(part)
+        except OSError as e:   # urllib's errors, timeouts and a bad file
+            remove(part)
+            rep.warning('warn.dlss_download_failed', url=DLSS_URL, detail=str(e)[:300])
+            return {'failed': True}
+        return {'installed': DLSS_VERSION}
+
+
+# ---- 8. clean up
 
 class Cleanup(Step):
     id = 'cleanup'
@@ -1182,4 +1255,4 @@ def romfs_problem(romfs, expected):
 
 
 def all_steps():
-    return [Check(), Fonts(), Extract(), Lift(), Compile(), Prepare(), Cleanup()]
+    return [Check(), Fonts(), Extract(), Lift(), Compile(), Prepare(), Dlss(), Cleanup()]

installer/text/en.json

@@ -5,6 +5,7 @@
  "step.lift": "Translating the game code to C",
  "step.compile": "Compiling {game_exe}",
  "step.prepare": "Preparing the shaders",
+ "step.dlss": "Downloading NVIDIA DLSS",
  "step.cleanup": "Cleaning up",
 
  "phase.check.host": "Checking the processor and the graphics card",
@@ -32,6 +33,7 @@
  "phase.prepare.translate": "Translating the shaders",
  "phase.prepare.libraries": "Building the shaders for the graphics driver",
  "phase.prepare.pack": "Packing the shader cache into one file",
+ "phase.dlss.download": "Downloading nvngx_dlss.dll from NVIDIA's DLSS SDK",
  "phase.cleanup.ini": "Writing totk.ini",
  "phase.cleanup.temp": "Removing temporary files",
 
@@ -104,6 +106,9 @@
  "warn.xbox_prompts_failed": "The Xbox button prompts could not be prepared (exit code {code}); the game keeps the Switch prompts. Details: {log}",
  "warn.shaders_skipped": "The graphics driver crashed while building some shaders, so {count} were left out of the preparation. The game builds them when it first needs them, and the driver may crash there too; a driver update may fix it. Details: {log}",
  "warn.kernel_old": "Linux {version} lacks the write tracking the game relies on (6.7 or later); the game may run very slowly. Updating the system fixes this.",
+ "warn.dlss_no_rtx": "No NVIDIA RTX graphics card was found, so NVIDIA DLSS was not downloaded; the game runs without it.",
+ "warn.dlss_kept": "A DLSS library is already in the install folder ({path}); the setup keeps it.",
+ "warn.dlss_download_failed": "NVIDIA DLSS could not be downloaded from {url}: {detail}. The game runs without it; the next setup run tries again.",
 
  "ui.title": "TotK Setup",
  "ui.rebuild_title": "Rebuilding the game for your mods",
@@ -125,6 +130,8 @@
  "ui.pick_firmware": "Choose the Switch firmware folder (Contents/registered)",
  "ui.pick_dest": "Choose the install folder",
  "ui.firmware_help": "For Chinese, Korean and Traditional Chinese text: the firmware's Contents/registered folder, for example from Ryujinx or Yuzu. The setup copies the Switch system fonts from it into the install folder.",
+ "ui.dlss": "Download NVIDIA DLSS (nvngx_dlss.dll) for NVIDIA RTX graphics cards",
+ "ui.dlss_help": "From NVIDIA's DLSS SDK on GitHub, under NVIDIA's RTX SDK license (github.com/NVIDIA/DLSS). It makes the dlaa and DLSS settings work; without it they do nothing.",
  "ui.compressed_help": "Compressed NSZ and XCZ files work as they are: the setup unpacks them by itself (until the game data is extracted, that needs as much free space as the unpacked files take).",
  "ui.type_game": "Game files (NSP, XCI, NSZ, XCZ)",
  "ui.type_keys": "Key files (*.keys)",

installer/text/pt-BR.json

@@ -5,6 +5,7 @@
  "step.lift": "Traduzindo o código do jogo para C",
  "step.compile": "Compilando o {game_exe}",
  "step.prepare": "Preparando os shaders",
+ "step.dlss": "Baixando o NVIDIA DLSS",
  "step.cleanup": "Finalizando",
 
  "phase.check.host": "Verificando o processador e a placa de vídeo",
@@ -32,6 +33,7 @@
  "phase.prepare.translate": "Traduzindo os shaders",
  "phase.prepare.libraries": "Montando os shaders para o driver de vídeo",
  "phase.prepare.pack": "Juntando o cache de shaders num único arquivo",
+ "phase.dlss.download": "Baixando o nvngx_dlss.dll do DLSS SDK da NVIDIA",
  "phase.cleanup.ini": "Gravando o totk.ini",
  "phase.cleanup.temp": "Removendo os arquivos temporários",
 
@@ -104,6 +106,9 @@
  "warn.xbox_prompts_failed": "Não foi possível preparar os ícones de botão do Xbox (código de saída {code}); o jogo mantém os ícones do Switch. Detalhes: {log}",
  "warn.shaders_skipped": "O driver gráfico travou ao compilar alguns shaders, então {count} ficaram fora da preparação. O jogo os compila quando precisar deles pela primeira vez, e o driver pode travar ali também; uma atualização do driver pode resolver. Detalhes: {log}",
  "warn.kernel_old": "O Linux {version} não tem o rastreamento de escrita de que o jogo depende (6.7 ou mais novo); o jogo pode rodar muito devagar. Atualizar o sistema resolve.",
+ "warn.dlss_no_rtx": "Nenhuma placa de vídeo NVIDIA RTX foi encontrada, então o NVIDIA DLSS não foi baixado; o jogo funciona sem ele.",
+ "warn.dlss_kept": "Já existe uma biblioteca DLSS na pasta de instalação ({path}); a instalação a mantém.",
+ "warn.dlss_download_failed": "Não foi possível baixar o NVIDIA DLSS de {url}: {detail}. O jogo funciona sem ele; a próxima execução da instalação tenta de novo.",
 
  "ui.title": "Instalação do TotK",
  "ui.rebuild_title": "Recompilando o jogo para os seus mods",
@@ -125,6 +130,8 @@
  "ui.pick_firmware": "Escolha a pasta de firmware do Switch (Contents/registered)",
  "ui.pick_dest": "Escolha a pasta de instalação",
  "ui.firmware_help": "Para textos em chinês, coreano e chinês tradicional: a pasta Contents/registered do firmware, por exemplo do Ryujinx ou do Yuzu. A instalação copia dela as fontes do sistema do Switch para a pasta de instalação.",
+ "ui.dlss": "Baixar o NVIDIA DLSS (nvngx_dlss.dll) para placas de vídeo NVIDIA RTX",
+ "ui.dlss_help": "Do DLSS SDK da NVIDIA no GitHub, sob a licença NVIDIA RTX SDK (github.com/NVIDIA/DLSS). Sem ele as opções dlaa e DLSS não fazem nada.",
  "ui.compressed_help": "Arquivos compactados NSZ e XCZ funcionam do jeito que estão: a instalação os descompacta sozinha (para isso, até os dados do jogo serem extraídos, ela precisa de tanto espaço livre quanto ocupam os arquivos descompactados).",
  "ui.type_game": "Arquivos de jogo (NSP, XCI, NSZ, XCZ)",
  "ui.type_keys": "Arquivos de chaves (*.keys)",

installer/text/ru.json

@@ -5,6 +5,7 @@
  "step.lift": "Перевод кода игры в C",
  "step.compile": "Сборка {game_exe}",
  "step.prepare": "Подготовка шейдеров",
+ "step.dlss": "Загрузка NVIDIA DLSS",
  "step.cleanup": "Уборка",
 
  "phase.check.host": "Проверка процессора и видеокарты",
@@ -32,6 +33,7 @@
  "phase.prepare.translate": "Трансляция шейдеров",
  "phase.prepare.libraries": "Сборка шейдеров для драйвера видеокарты",
  "phase.prepare.pack": "Упаковка кэша шейдеров в один файл",
+ "phase.dlss.download": "Загрузка nvngx_dlss.dll из DLSS SDK от NVIDIA",
  "phase.cleanup.ini": "Запись totk.ini",
  "phase.cleanup.temp": "Удаление временных файлов",
 
@@ -104,6 +106,9 @@
  "warn.xbox_prompts_failed": "Не удалось подготовить подсказки кнопок Xbox (код выхода {code}); игра оставит подсказки Switch. Подробности: {log}",
  "warn.shaders_skipped": "Графический драйвер аварийно завершился при сборке части шейдеров, поэтому {count} из них пропущены при подготовке. Игра соберёт их, когда они впервые понадобятся, и драйвер может упасть и там; обновление драйвера может это исправить. Подробности: {log}",
  "warn.kernel_old": "В Linux {version} нет отслеживания записи, на которое опирается игра (нужна версия 6.7 или новее); игра может работать очень медленно. Обновление системы это исправит.",
+ "warn.dlss_no_rtx": "Видеокарта NVIDIA RTX не найдена, поэтому NVIDIA DLSS не загружен; игра работает и без него.",
+ "warn.dlss_kept": "В папке установки уже есть библиотека DLSS ({path}); установка её оставляет.",
+ "warn.dlss_download_failed": "Не удалось загрузить NVIDIA DLSS с {url}: {detail}. Игра работает и без него; при следующем запуске установка попробует снова.",
 
  "ui.title": "Установка TotK",
  "ui.rebuild_title": "Пересборка игры под ваши моды",
@@ -125,6 +130,8 @@
  "ui.pick_firmware": "Выберите папку прошивки Switch (Contents/registered)",
  "ui.pick_dest": "Выберите папку установки",
  "ui.firmware_help": "Для текста на китайском и корейском: папка Contents/registered прошивки, например из Ryujinx или Yuzu. Установка скопирует из неё системные шрифты Switch в папку установки.",
+ "ui.dlss": "Загрузить NVIDIA DLSS (nvngx_dlss.dll) для видеокарт NVIDIA RTX",
+ "ui.dlss_help": "Из DLSS SDK от NVIDIA на GitHub, по лицензии NVIDIA RTX SDK (github.com/NVIDIA/DLSS). Без него настройки dlaa и DLSS ничего не делают.",
  "ui.compressed_help": "Сжатые файлы NSZ и XCZ подходят как есть: установка сама их распакует (для этого, пока извлекаются данные игры, нужно столько свободного места, сколько занимают распакованные файлы).",
  "ui.type_game": "Файлы игры (NSP, XCI, NSZ, XCZ)",
  "ui.type_keys": "Файлы ключей (*.keys)",

installer/text/zh-Hans.json

@@ -5,6 +5,7 @@
  "step.lift": "将游戏代码转换为 C 代码",
  "step.compile": "编译 {game_exe}",
  "step.prepare": "准备着色器",
+ "step.dlss": "下载 NVIDIA DLSS",
  "step.cleanup": "清理",
 
  "phase.check.host": "检查处理器和显卡",
@@ -32,6 +33,7 @@
  "phase.prepare.translate": "转译着色器",
  "phase.prepare.libraries": "为显卡驱动构建着色器",
  "phase.prepare.pack": "将着色器缓存打包成一个文件",
+ "phase.dlss.download": "从 NVIDIA 的 DLSS SDK 下载 nvngx_dlss.dll",
  "phase.cleanup.ini": "写入 totk.ini",
  "phase.cleanup.temp": "删除临时文件",
 
@@ -104,6 +106,9 @@
  "warn.xbox_prompts_failed": "无法准备 Xbox 按键提示（退出代码 {code}）；游戏将继续使用 Switch 按键提示。详情：{log}",
  "warn.shaders_skipped": "显卡驱动在编译部分着色器时崩溃，因此有 {count} 个着色器未被预先准备。游戏会在首次需要时编译它们，驱动在那时也可能崩溃；更新驱动可能会解决。详情：{log}",
  "warn.kernel_old": "Linux {version} 缺少游戏依赖的写入跟踪功能（需要 6.7 或更新版本）；游戏可能运行得很慢。更新系统即可解决。",
+ "warn.dlss_no_rtx": "未找到 NVIDIA RTX 显卡，因此未下载 NVIDIA DLSS；游戏无需它也能运行。",
+ "warn.dlss_kept": "安装文件夹中已有 DLSS 库（{path}）；安装程序将保留它。",
+ "warn.dlss_download_failed": "无法从 {url} 下载 NVIDIA DLSS：{detail}。游戏无需它也能运行；下次运行安装程序时会重试。",
 
  "ui.title": "TotK 安装程序",
  "ui.rebuild_title": "正在为你的模组重新构建游戏",
@@ -125,6 +130,8 @@
  "ui.pick_firmware": "选择 Switch 固件文件夹（Contents/registered）",
  "ui.pick_dest": "选择安装文件夹",
  "ui.firmware_help": "用于中文、韩文和繁体中文文本：固件的 Contents/registered 文件夹，例如来自 Ryujinx 或 Yuzu。安装程序会从中把 Switch 系统字体复制到安装文件夹。",
+ "ui.dlss": "为 NVIDIA RTX 显卡下载 NVIDIA DLSS（nvngx_dlss.dll）",
+ "ui.dlss_help": "来自 GitHub 上 NVIDIA 的 DLSS SDK，遵循 NVIDIA RTX SDK 许可（github.com/NVIDIA/DLSS）。没有它，dlaa 和 DLSS 设置不起作用。",
  "ui.compressed_help": "压缩的 NSZ 和 XCZ 文件可以直接使用：安装程序会自行解压（在游戏数据提取完成之前，需要与解压后文件大小相同的可用空间）。",
  "ui.type_game": "游戏文件（NSP、XCI、NSZ、XCZ）",
  "ui.type_keys": "密钥文件（*.keys）",

tests/installer_test.py

@@ -481,7 +481,7 @@ class FontsTest(unittest.TestCase):
 
     def test_all_steps_order(self):
         self.assertEqual([s.id for s in steps.all_steps()],
-                         ['check', 'fonts', 'extract', 'lift', 'compile', 'prepare', 'cleanup'])
+                         ['check', 'fonts', 'extract', 'lift', 'compile', 'prepare', 'dlss', 'cleanup'])
 
     def test_extracts_into_the_install_folder(self):
         self.fake_tool()
@@ -575,5 +575,68 @@ class EventsTest(unittest.TestCase):
         self.assertEqual(sorted(i for i in used if i not in catalog), [])
 
 
+@unittest.skipUnless(steps.os.name == 'nt', 'DLSS is Windows-only')
+class DlssTest(unittest.TestCase):
+    """The DLSS step: off without --dlss, needs an RTX GPU, keeps a player's library, verifies the download."""
+
+    def setUp(self):
+        self.tmp = tempfile.TemporaryDirectory()
+        base = Path(self.tmp.name)
+        self.dest, temp = base / 'dest', base / 'temp'
+        self.dest.mkdir()
+        temp.mkdir()
+        self.src = base / 'nvngx_dlss.dll'
+        self.src.write_bytes(b'dlss' * 1000)
+        self.saved = steps.DLSS_URL, steps.DLSS_SIZE, steps.DLSS_SHA256
+        steps.DLSS_URL = self.src.as_uri()   # urllib reads file: URLs as it reads https: ones
+        steps.DLSS_SIZE, steps.DLSS_SHA256 = 4000, steps.file_sha256(self.src)
+        rtx = {'devices': [{'name': 'NVIDIA GeForce RTX 4080 SUPER', 'api': [1, 4, 0], 'type': 2}]}
+        self.ctx = SimpleNamespace(dest=self.dest, temp=temp, host=rtx, reporter=Reporter(out=io.StringIO()),
+                                   options=SimpleNamespace(dlss=True))
+
+    def tearDown(self):
+        steps.DLSS_URL, steps.DLSS_SIZE, steps.DLSS_SHA256 = self.saved
+        self.ctx.reporter.close()
+        self.tmp.cleanup()
+
+    def warnings(self):
+        return [json.loads(line)['id'] for line in self.ctx.reporter.out.getvalue().splitlines()
+                if json.loads(line)['type'] == 'warning']
+
+    def test_off_without_the_option(self):
+        self.ctx.options.dlss = False
+        self.assertEqual(steps.Dlss().run(self.ctx), {})
+        self.assertFalse((self.dest / 'nvngx_dlss.dll').exists())
+        self.assertNotEqual(steps.Dlss().key(self.ctx), steps.Dlss().key(SimpleNamespace(options=SimpleNamespace(dlss=True))))
+
+    def test_downloads_and_checks_the_library(self):
+        rec = steps.Dlss().run(self.ctx)
+        self.assertEqual(rec, {'installed': steps.DLSS_VERSION})
+        self.assertEqual((self.dest / 'nvngx_dlss.dll').read_bytes(), self.src.read_bytes())
+        self.assertFalse(list(self.ctx.temp.iterdir()))
+        self.assertTrue(steps.Dlss().current(self.ctx, rec))
+        (self.dest / 'nvngx_dlss.dll').unlink()
+        self.assertFalse(steps.Dlss().current(self.ctx, rec))
+
+    def test_a_wrong_file_is_not_installed_and_tried_again(self):
+        steps.DLSS_SHA256 = '0' * 64
+        rec = steps.Dlss().run(self.ctx)
+        self.assertEqual(rec, {'failed': True})
+        self.assertFalse((self.dest / 'nvngx_dlss.dll').exists())
+        self.assertEqual(self.warnings(), ['warn.dlss_download_failed'])
+        self.assertFalse(steps.Dlss().current(self.ctx, rec))
+
+    def test_keeps_the_players_library(self):
+        (self.dest / 'nvngx_dlss.dll').write_bytes(b'newer')
+        self.assertEqual(steps.Dlss().run(self.ctx), {'kept': True})
+        self.assertEqual((self.dest / 'nvngx_dlss.dll').read_bytes(), b'newer')
+        self.assertEqual(self.warnings(), ['warn.dlss_kept'])
+
+    def test_skipped_without_an_rtx_gpu(self):
+        self.ctx.host = {'devices': [{'name': 'AMD Radeon RX 7800 XT', 'api': [1, 3, 0], 'type': 2}]}
+        self.assertEqual(steps.Dlss().run(self.ctx), {'skipped': 'no_rtx'})
+        self.assertEqual(self.warnings(), ['warn.dlss_no_rtx'])
+
+
 if __name__ == '__main__':
     unittest.main()