Hello Digitalis Samples

ARM64-only sample apps for testing Digitalis binary translation.

Credits

Most sample modules in this project are ported from the Android NDK Samples repository by Google, licensed under the Apache License 2.0. Modifications were made to build as ARM64-only modules for testing Digitalis binary translation.

The original hello-vulkan module was written for the Digitalis project.

Modules

Module	Description	Build
hello-vulkan	Vulkan triangle renderer	./gradlew :hello-vulkan:assembleDebug
hello-jni	Basic JNI — calls C code from Kotlin Activity	./gradlew :hello-jni:assembleDebug
hello-jniCallback	JNI callbacks — native code calls Java methods	./gradlew :hello-jniCallback:assembleDebug
exceptions	C++ exception handling across JNI boundary	./gradlew :exceptions:assembleDebug
bitmap-plasma	Plasma effect rendered to Android Bitmap via JNI	./gradlew :bitmap-plasma:assembleDebug
hello-gl2	OpenGL ES 2.0 triangle via JNI	./gradlew :hello-gl2:assembleDebug
gles3jni	OpenGL ES 3.0 with instanced rendering	./gradlew :gles3jni:assembleDebug
native-activity	Pure C++ NativeActivity with EGL/GLES rendering	./gradlew :native-activity:assembleDebug
native-audio	OpenSL ES audio playback and recording	./gradlew :native-audio:assembleDebug
native-codec	Video playback using Native Media Codec API	./gradlew :native-codec:assembleDebug
native-midi	Android Native MIDI API (requires Android 10+)	./gradlew :native-midi:assembleDebug
sensor-graph	Accelerometer sensor visualization with OpenGL	./gradlew :sensor-graph:assembleDebug
camera-basic	Camera2 NDK preview and JPEG capture	./gradlew :camera-basic:assembleDebug
camera-texture-view	Camera preview with TextureView rendering	./gradlew :camera-texture-view:assembleDebug
teapots-classic	Utah teapot with GLES 2.0 and touch gestures	./gradlew :teapots-classic:assembleDebug
teapots-more	GLES 3.0 instanced teapots rendering	./gradlew :teapots-more:assembleDebug
teapots-textured	Textured teapot with ImageDecoder (Android 11+)	./gradlew :teapots-textured:assembleDebug
endless-tunnel	3D tunnel game with scene management and GLES 2.0	./gradlew :endless-tunnel:assembleDebug
sanitizers	Address/UB sanitizer demo (HWASan/ASan/UBSan)	./gradlew :sanitizers:assembleDebug
unit-test	Native unit testing with GoogleTest via Prefab	./gradlew :unit-test:assembleDebug
vectorization	SIMD vectorization benchmarks (matrix multiplication)	./gradlew :vectorization:assembleDebug
orderfile	Binary optimization with linker order files	./gradlew :orderfile:assembleDebug
hello-gles1	GLES 1.x proxy-lib smoke test (libGLESv1_CM)	./gradlew :hello-gles1:assembleDebug
hello-gles3	OpenGL ES 3.2 EGL context repro (granted as host-max ES 3.1)	./gradlew :hello-gles3:assembleDebug
hello-lynx	Lynx (ReactLynx + PrimJS) native UI engine sample	./gradlew :hello-lynx:assembleDebug
hello-mmkv	Tencent MMKV native key-value store (libmmkv.so)	./gradlew :hello-mmkv:assembleDebug
hello-aaudio	AAudio proxy-lib smoke test (libaaudio)	./gradlew :hello-aaudio:assembleDebug
hello-binder-ndk	NDK Binder proxy-lib smoke test (libbinder_ndk)	./gradlew :hello-binder-ndk:assembleDebug
hello-nnapi	NNAPI proxy-lib smoke test (libneuralnetworks)	./gradlew :hello-nnapi:assembleDebug
hello-fp-vector	NEON vector FP three-same regression (FMUL/FADD/FSUB/FMLA/FMLS on .4S and .2D)	./gradlew :hello-fp-vector:assembleDebug

Prerequisites

• Android SDK with NDK (cmake 3.22.1+)
• glslangValidator for GLSL-to-SPIR-V shader compilation (included in the NDK's shader-tools/ or install via the Vulkan SDK)

Build

Build all modules:

./gradlew assembleDebug

Install and Run

On the Digitalis emulator (x86_64 with NativeBridge):

adb install hello-vulkan/build/outputs/apk/debug/hello-vulkan-debug.apk
adb shell am start -n com.example.hellodigitalis/android.app.NativeActivity

The apps are ARM64-only (arm64-v8a). They will not run on x86_64 devices without NativeBridge binary translation.

Digitalis Compatibility

Tested on the Digitalis x86_64 emulator with ARM64-to-x86_64 binary translation.

26 PASS / 0 CRASH for the original sample modules; the new hello-fp-vector regression sample is PARTIAL (3/5 vector-FP ops pass — see the table below).

Required smoke target: VulkanCapsViewer

vulkancapsviewer/ pins Sascha Willems' VulkanCapsViewer at tag 4.11 as a git submodule, with Vulkan-Headers v1.4.340 as its sub-submodule. vulkancapsviewer-test/ wraps it with a smoke-test runner (test.sh) that installs a pre-built APK on the connected Digitalis emulator, launches the Qt activity, and watches logcat for Undefined arm64 instruction / FATAL EXCEPTION / process death.

This is a required end-to-end translation test, not optional — it's the cross-check that the FMUL .4S / PAC / interpreter-fallback fixes hold together on a real Qt+Vulkan workload rather than just the unit-style hello-fp-vector probe. The submodules are pulled automatically by repo sync (the sample/hellodigitalis entry in .repo/manifests/digitalis.xml carries sync-s="true") or with git submodule update --init --recursive in a manual clone.

See vulkancapsviewer-test/README.md for the two paths to obtain the APK (upstream GitHub release, or a Qt-SDK build from the submodule).

Module	Status	Notes
hello-vulkan	PASS	Vulkan triangle renders correctly
hello-jni	PASS	Basic JNI works
hello-jniCallback	PASS	JNI callbacks work
exceptions	PASS	C++ exceptions work across JNI
bitmap-plasma	PASS	Plasma effect renders correctly
hello-gl2	PASS	GLES 2.0 triangle renders
gles3jni	PASS	GLES 3.0 instanced rendering works
native-activity	PASS	NativeActivity with EGL/GLES works
native-audio	PASS	OpenSL ES audio works
native-codec	PASS	Media codec playback works
native-midi	PASS	MIDI API loads (no device on emulator)
sensor-graph	PASS	Accelerometer graph renders
camera-basic	PASS	Camera2 NDK works
camera-texture-view	PASS	Camera TextureView works
teapots-classic	PASS	GLES 2.0 teapot renders
teapots-more	PASS	GLES 3.0 instanced teapots render
teapots-textured	PASS	Textured teapot renders (with ifstream workaround)
endless-tunnel	PASS	3D tunnel game runs
sanitizers	PASS	Sanitizer demo runs
unit-test	PASS	GoogleTest runs
vectorization	PASS	SIMD benchmarks run
orderfile	PASS	Order file demo runs
hello-gles1	PASS	glGetError() resolves through libberberis_proxy_libGLESv1_CM.so
hello-gles3	PASS	ES 3.2 eglCreateContext granted as ES 3.1 (gfxstream guest-EGL clamp); renders a deterministic pattern
hello-lynx	PASS	Lynx engine + PrimJS JS runtime execute the prebuilt .lynx.bundle; ReactLynx page renders under translation
hello-mmkv	PASS	Tencent MMKV libmmkv.so loads; int/bool/long/double/string/bytes round-trip through MMKV's mmap-backed native store
hello-aaudio	PASS	AAudio_createStreamBuilder resolves through libberberis_proxy_libaaudio.so
hello-binder-ndk	PASS	AIBinder_Class_define / AIBinder_new resolve through libberberis_proxy_libbinder_ndk.so
hello-nnapi	PASS	ANeuralNetworks_getDeviceCount resolves through libberberis_proxy_libneuralnetworks.so
hello-fp-vector	PARTIAL	.4S/.2D FMUL/FADD/FSUB pass; FMLA/FMLS still fail pending the JIT→interpreter Vd-flush fix (see translator commit notes)

Known Workarounds

• teapots-textured (ndk_helper/JNIHelper.cpp): std::ifstream construction is wrapped in try { … } catch (...) and falls through to AAssetManager on any exception. The fallback path is the standard way to read APK assets anyway, so this is the right shape long-term whether or not the translator-side issue (std::locale construction throwing) is later fixed.