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Making friends with robots
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Agenda
• Building hello-world for Android
• Building Fiber2D project for Android
• Swift + Java = <3
• Overview
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Hello world
• Linux environment
• Ubuntu 15.10 is the only officially supported
• 16.04 is used in Fiber2D
• NDK (r13 and later)
• Android API Version 21+
• Android device (meh…) with remote debugging
Prerequisites
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Main header
• Installing curl, autoconf, automake, libtool, git + CMake (!)
• Getting Android NDK r13b (and later)
• Getting SwiftAndroid/libiconv-libicu-android
Building dependencies
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Hello world
Building Swift compiler
$ utils/build-script -R \ --android \ --android-ndk $ANDROID_NDK_HOME \ --android-api-level 21 \ --android-icu-uc $ANDROID_LIBICONV/armeabi-v7a \ --android-icu-uc-include $ANDROID_LIBICONV/armeabi-v7a/icu/source/common \ --android-icu-i18n $ANDROID_LIBICONV/armeabi-v7a \ --android-icu-i18n-include $ANDROID_LIBICONV/armeabi-v7a/icu/source/i18n/
Export $ANDROID_NDK_HOME and $ANDROID_LIBICONV
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Hello world
Before building the executable
sudo ln -s \ $ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/bin/ld.gold \ /usr/bin/armv7-none-linux-androideabi-ld.gold
Let Swift compiler find the correct linker (gold)
From docs:
Also needed:sudo ln -s \ $ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/bin/ld.gold \ /usr/bin/armv7-none-linux-android-ld.gold
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Hello world
Notes: compiler flags
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• -l[foo] : Link to libfoo[.so][.dylib]XCode: Other Link Flags
• -L[/path/foo] : Search path for linked libraries XCode: Library Search Paths
• -I[/path/foo] : Search path for headers (C/C++) or .swiftmodule (Swift) XCode: Header Search Paths/Import Paths
• -D[FLAG] : Preprocessor flag (#if FLAG) XCode: Preprocessor macros
Hello world
Building the executable
$ build/Ninja-ReleaseAssert/swift-linux-x86_64/bin/swiftc \ -target armv7-none-linux-androideabi \ -sdk $ANDROID_NDK_HOME/platforms/android-21/arch-arm \ -L $ANDROID_NDK_HOME/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a \ -L $ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9 \ hello.swift
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Hello world
Deploying the executableStandalone Swift executable requires this to run:
• libswiftCore.so • libswiftGlibc.so • libswiftRemoteMirror.so • libswiftSwiftOnoneSupport.so
and this:• libc++_shared.so
finally, push the executable:
adb push hello /data/local/tmp
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adb shell LD_LIBRARY_PATH=/data/local/tmp \/data/local/tmp/hello
Hello world
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Compiling Fiber2D
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Compiling Fiber2D
The goal
• Swift Package Manager at the heart of build process • Compile Fiber2D framework • Use it in the real world (.apk) Android application
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Compiling Fiber2D
Project structure
Fiber2D
Cpng CChipmunk2DSwiftMath
SwiftBGFX
Cbgfx
bgfx
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Compiling Fiber2D
Project structure
Fiber2D
Cpng CChipmunk2DSwiftMath
SwiftBGFX
Cbgfx
bgfx
Legend: • C++ • C • Swift
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Compiling Fiber2D
SwiftPM limitations
• Does not allow mixing languages within one target • No Bridging-Headers • No custom source code layouts • No custom local config (-l/-L/-I/-D flags) • No custom scripts/makefiles
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Compiling Fiber2D
Notes: module maps
module CChipmunk2D { header "chipmunk_private.h" header "chipmunk.h" header "cpHastySpace.h" link "CChipmunk2D" export * }
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Compiling Fiber2D
NDK• Android apps are Java-based • Android NDK lets you implement parts of your app using
native-code languages such as C and C++ • Java to C calls are handled by Java Native Interface (JNI)
public class MyActivity extends Activity { /** * Native method implemented in C/C++ */ public native void computeFoo();}
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Compiling Fiber2D
NDK
• NDK project must contain jni folder at its root • ndk-build command recursively traverses it and
compiles every Android.mk it can find • Compiled binaries are stored in libs/<ARCH> folders
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Compiling Fiber2D
SDL
• SDL - low-level abstraction layer for audio, keyboard, mouse, joystick, and graphics hardware
• Provides Android template project with JNI shim • Wants you to add your C/C++ files to its main lib’s
Android.mk:# Add your application source files here... LOCAL_SRC_FILES := $(SDL_PATH)/src/main/android/SDL_android_main.c
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Compiling Fiber2D
What SDL does not tell us?
#define main SDL_main // And then extern C_LINKAGE int SDL_main(int argc, char *argv[]);
• SDL secretly redefines main function with its own macro on certain platforms:
• We can’t use it in Swift
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Compiling Fiber2D
What we want to do?
• Compile SDL and boilerplate code only once • Compile our project as dynamic library • Put it into Android project • Load it during the runtime • Make SDL call our SDL_main implementation
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Compiling Fiber2D
Notes: Swift name mangling
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class Shape { func numberOfSides() -> Int { return 5 } }
_TFC9swifttest5Shape17simpleDescriptionfS0_FT_Si
JFYI: You can use swift-demangle
Compiling Fiber2D
Implementing SDL_main
• Make sure you don’t have main.swift • Use @_silgen_name or @_cdecl attributes to overcome
Swift symbol mangling
@_cdecl("SDL_main")public func SDL_main(argc: Int32, argv: OpaquePointer) -> Int32 { …}
• Function must be top-level, public and can’t throw
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Compiling Fiber2D
Creating the build script
• To build SwiftPM package you do swift build • swift != swiftc • Use -Xlinker, -Xcc and -Xswiftc to forward flags • Declarations with spaces requires multiple -X* flags, i.e.: -Xlinker -framework -Xlinker AppKit
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Compiling Fiber2D
Creating the build script
First, add flags that we used to build hello-world:-Xswiftc -target -Xswiftc armv7-none-linux-androideabi \ -Xswiftc -sdk -Xswiftc $ANDROID_NDK_HOME/platforms/android-21/arch-arm \ -Xlinker -L$ANDROID_NDK_HOME/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a \ -Xlinker -L$ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/
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Compiling Fiber2D
Creating the build script
Add Fiber2D include paths:-Xswiftc -I../../../../.build/debug \-Xswiftc -I../../../../.build/checkouts/Cpng-8308068493617107876/Cpng/include \-Xswiftc -I../../../../.build/checkouts/CChipmunk2D--4671306517288557973/CChipmunk2D/include \-Xswiftc -I../../../../external/SwiftBGFX/.build/debug \-Xswiftc -I../android-project/jni/SDL2-2.0.5/include \
Android-specific ones:-Xswiftc -I$ANDROID_NDK_HOME/sources/android/native_app_glue/ \-Xcc -I$ANDROID_NDK_HOME/platforms/android-21/arch-arm/usr/include \
And some for Foundation:-Xswiftc -I$ANDROID_SWIFT_SOURCE/build/Ninja-ReleaseAssert/foundation-linux-x86_64/Foundation \-Xswiftc -I$ANDROID_SWIFT_SOURCE/swift-corelibs-foundation \-Xswiftc -I$ANDROID_SWIFT_SOURCE/swift-corelibs-foundation/closure \
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Compiling Fiber2D
Creating the build script
Link to libraries:-Xlinker -lgcc -Xlinker -lc++ -Xlinker -ldispatch \-Xlinker -lFoundation -Xlinker -latomic -Xlinker -lFiber2D \-Xlinker -licui18n -Xlinker -licuuc \
Add library search paths for libDispatch and libFoundation:-Xlinker -L/usr/local/lib/swift/android/ \-Xlinker -L$ANDROID_SWIFT_SOURCE/build/Ninja-ReleaseAssert/foundation-linux-x86_64/Foundation/ \
Add library search paths for Android stuff:-Xlinker -L$ANDROID_NDK_HOME/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a \-Xlinker -L$ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/ \-Xlinker -L$ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/lib/armv7-a/ \-Xlinker -L$ANDROID_LIBICONV/armeabi-v7a \
And for Fiber2D:-Xlinker -L../../../../.build/debug \-Xlinker -L../../../../external/SwiftBGFX/.build/debug \
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Compiling Fiber2D
Creating the build script
Compile libSwiftMath without SIMD:-Xswiftc -DNOSIMD \
Add cross-compilation flags:-Xcc -B -Xcc $ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/bin/ \-Xcc --sysroot=$ANDROID_NDK_HOME/platforms/android-21/arch-arm/ \-Xlinker --sysroot=$ANDROID_NDK_HOME/platforms/android-21/arch-arm/ # This does not work for now and requires a hack for clang
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Compiling Fiber2D
Build script:cd f2dc swift build \ -Xswiftc -I$ANDROID_NDK_HOME/sources/android/native_app_glue/ \ -Xcc -I$ANDROID_NDK_HOME/platforms/android-21/arch-arm/usr/include \ -Xswiftc -I../../../../.build/debug \ -Xswiftc -I../../../../.build/checkouts/Cpng-8308068493617107876/Cpng/include \ -Xswiftc -I../../../../.build/checkouts/CChipmunk2D--4671306517288557973/CChipmunk2D/include \ -Xswiftc -I../../../../external/SwiftBGFX/.build/debug \ -Xswiftc -I../android-project/jni/SDL2-2.0.5/include \ -Xswiftc -I$ANDROID_SWIFT_SOURCE/build/Ninja-ReleaseAssert/foundation-linux-x86_64/Foundation \ -Xswiftc -I$ANDROID_SWIFT_SOURCE/swift-corelibs-foundation \ -Xswiftc -I$ANDROID_SWIFT_SOURCE/swift-corelibs-foundation/closure \ -Xswiftc -target -Xswiftc armv7-none-linux-androideabi \ -Xswiftc -sdk -Xswiftc $ANDROID_NDK_HOME/platforms/android-21/arch-arm \ -Xswiftc -DNOSIMD \ -Xcc -target -Xcc armv7-none-linux-androideabi \ -Xcc -B -Xcc $ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/bin/ \ -Xcc --sysroot=$ANDROID_NDK_HOME/platforms/android-21/arch-arm/ \ -Xlinker -L/usr/local/lib/swift/android/ \ -Xlinker -L$ANDROID_SWIFT_SOURCE/build/Ninja-ReleaseAssert/foundation-linux-x86_64/Foundation/ \ -Xlinker -L$ANDROID_NDK_HOME/sources/cxx-stl/llvm-libc++/libs/armeabi-v7a \ -Xlinker -L$ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/lib/gcc/arm-linux-androideabi/4.9.x/ \ -Xlinker -L$ANDROID_NDK_HOME/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/lib/armv7-a/ \ -Xlinker -L$ANDROID_LIBICONV/armeabi-v7a \ -Xlinker -L../../../../.build/debug \ -Xlinker -L../../../../external/SwiftBGFX/.build/debug \ -Xlinker -L../android-project/libs/armeabi-v7a \ -Xlinker -lgcc -Xlinker -lc++ -Xlinker -ldispatch \ -Xlinker -lFoundation -Xlinker -latomic -Xlinker -lFiber2D \ -Xlinker -licui18n -Xlinker -licuuc \ -Xlinker --sysroot=$ANDROID_NDK_HOME/platforms/android-21/arch-arm/ # This does not work for now and requires a hack for clang
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Compiling Fiber2D
clang hack
#!/bin/bash
# This is a proxy hack until it gets fixed in SPM # You have to add chmod +x to this file /usr/bin/@clang -target armv7-none-linux-androideabi \ -B $(ANDROID_NDK_HOME)/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/arm-linux-androideabi/bin/ \ —sysroot=$(ANDROID_NDK_HOME)/platforms/android-21/arch-arm/ $*
• Linking C/C++ with Swift is done by clang • SwiftPM does not pass platform flags for cross-
compilation (-B/—sysroot/-target) to clang during linkage stage (even when passed via -Xlinker)
• So we had to do a proxy clang script • mv /usr/bin/clang /usr/bin/@clang • chmod +x /usr/bin/clang
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Compiling Fiber2D
Compiling libSDL2 and libmain
• Put freshly compiled libf2dc.so lib to jni/dependncies
• Add -lf2dc -Ljni/dependencies to main lib’s Android.mk
• Run ndk-build in the project root
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Compiling Fiber2D
SDL hack + pure NDK
• As we wanted to use custom renderer we had to hack in SDL to prevent it from managing the window’s context
• We create CAndroidAppGlue package to wrap pure NDK API into Swift Module
• It is possible to create pure Swift + Java app
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Compiling Fiber2D
Putting Swift binaries into .apk
libCbgfx.so libCChipmunk2D.so
libCpng.so libcurlll.so
libdispatch.so libf2dc.so
libFiber2D.so libFoundation.so libscudata.so libscui18n.so libscuuc.so
libSwiftBGFX.so libswiftCore.so libswiftGlibc.so
libswiftRemoteMirror.so libswiftSwiftOnoneSupport.so
libxml222.so libc++_shared.so
Copy these libraries to libs/armeabi-v7a:
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Compiling Fiber2D
Notes: executable file formats
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• PE (Windows) • Mach-O (Mac/iOS) • ELF (Linux/Android)
Contain executable format, architecture type and program header
Compiling Fiber2D
Notes: executable file formats
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Compiling Fiber2D
Putting Swift binaries into .apk
Note that Android 5 manages sub-dependencies on its own, but on Android 4.4 you have to put all libs to
System.load section of SDLActivity.java
protected String[] getLibraries() { return new String[] { "SDL2", "main" }; }
// Load the .so public void loadLibraries() { for (String lib : getLibraries()) { System.loadLibrary(lib); } }
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Compiling Fiber2D
Deploying the app
• ant debug install • Run the app from Android launcher • Use logcat to debug (NSLog() instead of print())
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Compiling Fiber2D
libicu hack
• Android linker ignores LD_LIBRARY_PATH when loading with System.loadLibrary()
• Android is shipped with its own outdated version of libicu
• We have to ship our own libraries • And hack into compiled binaries…
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Compiling Fiber2D
libicu hack
• We have to fool Android linker to load our version of libicu
• Conventional hack: rename libi***.so to libs***.so
• Rename binary links as well: rpl -R -e libicu libscu lib*.so
• Note: keep the strings you change the same length
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Compiling Fiber2D
libxml/libcurl hackreadelf -d libFoundation.so
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Compiling Fiber2D
libxml/libcurl hackreadelf -d libFoundation.so
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Compiling Fiber2D
libxml/libcurl hack• Android can’t load libraries via symlinks or custom
names • We have to ship our own versions of libxml and libcurl
• You can find initial binaries in $ANDROID_NDK_HOME/sysroot/src/libxml2/.libs
• Rename: libxml2.so.2 to libxml222.solibcurl.so.5 to libcurlll.so
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Compiling Fiber2D
Results
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Compiling Fiber2D
Results
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Swift + Java = <3
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Swift + Java
Calling from Java into C
Compile your C code as dynamic library, load it at runtime
System.loadLibrary("fooLib");
Define method with native keyword
public native Int intFromJNI();
Java side:
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Swift + Java
Calling from Java into C
C side:JNIEXPORT jint JNICALL Java_com_example_app_HelloJNI_intFromJNI( JNIEnv* env, jobject thiz )
• JNI naming rule:Java_[package_name]_[class_name]_[exported_function_name]
• JNIEnv* is the pointer to the VM, and jobject is a pointer to the implicit this object passed from the Java side.
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Swift + Java
Calling from Java into Swift• Compile your Swift code as shared object library (.so),
load it at runtime • Use @_silgen_name or @_cdecl to create JNI
declaration • Call your top-level public Swift func whatever you want
internally
@_silgen_name(«Java_com_example_app__OurHello_intFromJNI") public func fooWhatever(env: UnsafeMutablePointer<JNIEnv>, jobj: jobject, x: jint, y: jint) -> jint { return x + y }
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Swift + Java
Calling from Swift into Java
Hint: create dummy XCode project and add «jni.h» to Bridging Header
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Swift + Java
Calling from Swift into Java
private func foo(env: UnsafeMutablePointer<JNIEnv>, jobj: jobject, value: jint) { let jni = env.memory.memory let methodName = "foo" let methodSignature = "(I)V" let javaClass = jni.GetObjectClass(env, jobj) let methodID = jni.GetMethodID(env, javaClass, methodName, methodSignature) let valueAsJValue = jvalue(i: value) var methodArgs: [jvalue] = [valueAsJValue] jni.CallVoidMethodA(env, jobj, methodID, &methodArgs) }
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Swift + Java
Decoding calling from Swift into Java
… func foo(env: UnsafeMutablePointer<JNIEnv> …
env is passed by Java.
env JNIEnv JNINativeInterface
let jni = env.memory.memory
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Swift + Java
Decoding calling from Swift into Java
let methodName = "foo" let methodSignature = "(I)V" let javaClass = jni.GetObjectClass(env, jobj) let methodID = jni.GetMethodID(env, javaClass, methodName, methodSignature)
Next we have to get an object and a method signature to be called according to Oracle JNI Docs
(I)V means that method receives one Int argument and returns Void
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Swift + Java
Decoding calling from Swift into Java
• Actual calling should be done with Call(ReturnType)MethodA
• All args must be wrapped into jvalue struct
let valueAsJValue = jvalue(i: value) var methodArgs: [jvalue] = [valueAsJValue] jni.CallVoidMethodA(env, jobj, methodID, &methodArgs)
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What’s good
• Code once, run everywhere (really)
• Speed
• Swift itself
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Try the future today!Okay, maybe not that exciting…
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What’s bad not ideal• App size overhead
• No macOS cross-compiling
• Compilation is not easy
• Native stuff (i.e. In-Apps) is not easy as well
• GPU is bad for dirty-rectangles type of apps
• MIPS, x86 and simulators are not supported yet
• No SIMD/NEON support
• No lldb (yet)
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That’s it!
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