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The project provides a unified build script that handles cross-compilation and backend selection for both Android and iOS platforms.

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Basic Usage

./scripts/build.sh <platform> [options]
Platforms:
  • android - Build for Android
  • ios - Build for iOS

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Options

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Build Configuration

OptionDescriptionDefault
--releaseBuild in release mode (optimized)Yes
--debugBuild in debug mode (with symbols)No

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Backend Selection

OptionDescriptionDefault
--rustUse Rust backend onlyYes
--cemuUse CEmu backend onlyNo
--bothInclude both backends (runtime switching)No

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Platform-Specific Options

Android:
OptionDescriptionDefault
--installInstall APK after buildNo
--all-abisBuild for all ABIs (arm64, arm32, x86_64, x86)No (arm64 only)
iOS:
OptionDescriptionDefault
--simBuild for iOS SimulatorNo (device)
--openOpen Xcode after building backendNo

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Other Options

OptionDescription
--helpShow help message

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Android Examples

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Basic Builds

# Release build, ARM64 only, Rust backend
./scripts/build.sh android

# Debug build with installation
./scripts/build.sh android --debug --install

# Release build for all ABIs
./scripts/build.sh android --all-abis

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Backend Selection

# Build with CEmu backend only
./scripts/build.sh android --cemu

# Build with both backends (runtime switching)
./scripts/build.sh android --both --install

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Output Location

Built APKs are placed in: 
android/app/build/outputs/apk/release/app-release.apk  # Release
android/app/build/outputs/apk/debug/app-debug.apk      # Debug

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iOS Examples

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Basic Builds

# Release build for device, Rust backend
./scripts/build.sh ios

# Debug build for device
./scripts/build.sh ios --debug

# Release build for simulator
./scripts/build.sh ios --sim

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Backend Selection

# Build device with CEmu backend
./scripts/build.sh ios --cemu

# Build simulator with both backends
./scripts/build.sh ios --sim --both

# Build and open Xcode
./scripts/build.sh ios --sim --open

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iOS Build Process

The build script only compiles the backend library (Rust and/or CEmu). After running the script:
  1. Open the Xcode project: 
    open ios/Calc.xcodeproj
  2. Select the appropriate scheme:
    • Calc-Rust - Rust backend only
    • Calc-CEmu - CEmu backend only
    • Calc-Both - Both backends with runtime switching
  3. Press Cmd+R to build and run the app

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Output Location

Backend libraries are placed in: 
core/target/aarch64-apple-ios/release/libemu_rust.a              # Device
core/target/aarch64-apple-ios-sim/release/libemu_rust.a          # Simulator (Apple Silicon)
core/target/x86_64-apple-ios/release/libemu_rust.a               # Simulator (Intel)
core/target/<arch>/release/libemu_cemu.a                          # CEmu adapter

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Make Targets (Shortcuts)

For convenience, the project includes Make targets as shortcuts for common build commands.

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Android Make Targets

# Rust backend (default)
make android              # Release, arm64, Rust
make android-debug        # Debug, arm64, Rust
make android-install      # Release + install, all ABIs

# Both backends
make android-both         # Release, both backends
make android-both-install # Release + install, both backends

# CEmu backend only
make android-cemu         # Release, CEmu only
make android-cemu-install # Release + install, CEmu

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iOS Make Targets

# Rust backend (default)
make ios             # Release, device, Rust
make ios-debug       # Debug, device, Rust
make ios-sim         # Release, simulator, Rust

# Both backends
make ios-both        # Release, device, both backends
make ios-sim-both    # Release, simulator, both backends

# CEmu backend only
make ios-cemu        # Release, device, CEmu
make ios-sim-cemu    # Release, simulator, CEmu

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Utility Make Targets

make test            # Run Rust unit tests
make clean           # Clean all build artifacts
make help            # Show all available targets

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Build Process Details

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Android Build Steps

  1. Rust Core Compilation (if --rust)
    • Detects Android NDK location
    • Adds NDK toolchain to PATH
    • Builds Rust core for target ABIs
    • Output: core/target/<abi>/release/libemu_core.a
  2. Gradle Build
    • Cleans CMake cache if backend changed
    • Passes backend flags to Gradle
    • Compiles native code (JNI bridge + backend)
    • Assembles APK
  3. Installation (if --install)
    • Uninstalls existing app
    • Installs new APK via adb

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iOS Build Steps

  1. Rust Core Compilation (if --rust)
    • Determines target architecture (device or simulator)
    • Builds with ios_prefixed feature (exports rust_* symbols)
    • Copies to libemu_rust.a
  2. CEmu Adapter Compilation (if --cemu)
    • Generates CMakeLists.txt for CEmu sources
    • Builds with CMake/Xcode for iOS target
    • Copies to libemu_cemu.a
  3. Xcode Integration
    • Backend libraries are statically linked by Xcode
    • backend_bridge.c provides unified API and runtime switching

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Troubleshooting

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Android NDK Not Found

Error: ANDROID_NDK_HOME not set and couldn't find NDK automatically.
Solution: Set the environment variable: 
export ANDROID_NDK_HOME=$ANDROID_HOME/ndk/<version>

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CEmu Not Found

Error: cemu-ref not found. Please clone CEmu first
Solution: Clone the CEmu repository: 
git clone https://github.com/CE-Programming/CEmu.git cemu-ref

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Rust Target Not Installed

If you see “error: toolchain ‘stable-…’ does not have target ’…’”: 
# Android
rustup target add aarch64-linux-android

# iOS Device
rustup target add aarch64-apple-ios

# iOS Simulator
rustup target add aarch64-apple-ios-sim  # Apple Silicon
rustup target add x86_64-apple-ios       # Intel

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Next Steps

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