cppandroidtest — C++/NDK Android template + on-device profiler

A forkable starting point for a serious C++ Android project, plus a built-in hardware profiler. It's the plumbing that normally costs days — NDK + CMake + C++23, a Kotlin↔C++ JNI bridge, four CI workflows, a tagged-release pipeline, a native crash handler, and an optional physical rooted-device test rig — wired together and battle-tested.

It is not a game engine or a world-scale app skeleton. It's a clean base a solo dev forks to start a native Android project (game, DSP, ML inference, firmware tooling, emulator…), with a profiler that tells you the performance envelope of your target devices before you write a line of your own code.

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Use it

1. Click "Use this template" on GitHub (or fork).

2. Make it yours — one command from the repo root:

   bash scripts/init-template.sh com.yourname.app "Your App" [libname] [--minimal]

   This renames the package everywhere it's coupled — the Kotlin source directory, the JNI symbol names (Java_<pkg>_MainActivity_*, which must stay in lockstep or the app crashes at first JNI call), applicationId, the native lib, the app display name — then statically validates the result. --minimal also strips the rooted-device test rig (keep it only if you have a device like the author's).

3. git add -A && commit && push. CI builds the renamed APK. Done.

Can't fully build locally without the NDK — init-template.sh does strong static checks (no stale identifiers, JNI⇄Kotlin package lockstep); CI confirms the build.

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Module map — keep what you need

Layer	Lives in	Keep if…	Drop by
Core scaffold	app/ (build.gradle, CMakeLists, MainActivity.kt, jni.cpp), .github/workflows/{smoke,quality,tests,release}.yml	always	—
Profiler	app/src/main/cpp/bench/**, scripts/{build-bench,run-bench,compare,dashboard}	you want CPU/memory/thermal/sensor/camera measurement	delete bench/, drop the registry calls in jni.cpp/bench_main.cpp
Device-test rig	scripts/{device-harness,ui_tap,aggregate-runs,live-dashboard}, .github/workflows/device-test.yml	you have a rooted test phone + self-hosted runner	--minimal at init, or git rm them

The profiler and device rig are opt-out, not load-bearing — the core builds and ships an APK without them.

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Build & run

# APK (debug): needs Android Studio's Gradle or a standalone gradle on PATH
gradle wrapper --gradle-version 8.7 --distribution-type bin   # once
./gradlew assembleDebug          # app/build/outputs/apk/debug/app-debug.apk
./gradlew installDebug           # build + adb install

# Standalone profiler ELF (arm64): no APK needed
bash scripts/build-bench.sh                                   # build/bench-arm64/cppbench
adb push build/bench-arm64/cppbench /data/local/tmp/ && adb shell chmod 755 /data/local/tmp/cppbench
adb shell /data/local/tmp/cppbench --json                    # benchmarks
adb shell /data/local/tmp/cppbench --sensors                 # all sensors
adb shell /data/local/tmp/cppbench --cameras                 # all cameras

# Host unit tests (no device)
cmake -S tests -B tests/build -G Ninja && cmake --build tests/build && ctest --test-dir tests/build

# Release: tag it
git tag v1.0.0 && git push origin v1.0.0   # CI builds + publishes APK & ELF

What the profiler measures

CPU stream (DRAM bandwidth), latency (cache hierarchy), neon_fma (FP32/FP16 GFLOPS), dot_int8 (SDOT/UDOT), i8mm + sve2 (ARMv9, opt-in), perf_counters (PMU via perf_event_open), sustained (thermal-throttling curve) — each pinned per CPU cluster. Plus full sensor & Camera2 enumeration and an NDJSON --stream mode with a terminal dashboard. Extension benches are runtime-gated on getauxval(AT_HWCAP) so they no-op (never SIGILL) on unsupported silicon.

CI workflows

Workflow	Runs on	Does
smoke	GitHub emulator (API 30, x86_64)	install APK, launch, assert it lives
quality	GitHub-hosted	clang-tidy + lizard cyclomatic complexity
tests	GitHub-hosted	host unit tests (doctest)
release	GitHub-hosted	build + publish APK & cppbench ELF on v* tags
device-test	self-hosted (optional)	bench + UI smoke on a real rooted device

Deeper docs

CLAUDE.md — architecture, the -u ANativeActivity_onCreate / HWCAP / per-file -march gotchas, the device rig, and the calibrated Exynos 9825 baseline.

Built with Claude Code. Debug-signed releases (not Play-Store eligible).