Add build instructionds for Android

android/README.md

@@ -0,0 +1,72 @@
+# Build pEpJNIAdapter for Android
+
+** Asuming machine is already set up to build pEp Engine and Sequoia! **
+## Install dependencies
+
+```bash 
+sudo port -N install gsed wget autoconf automake libtool md5sha1sum openjdk8
+
+## optionaly (not needed if using Android Studio)
+sudo port -N install gradle
+
+```
+
+## Install NDK
+It can be done with the SDK and the sdkmanager cli tool, or using Android Studio.
+
+Android studio -> Configure  -> SDK Manager -> SDK Tools (tab) -> Select NDK and install
+
+Tip: To install other versions click on "Show packages details" and select the desired NDK version (Currently using: 21.0.6113669)
+
+## Required env\_vars (for MacOS):
+
+``` bash
+export JAVA_HOME=$(/usr/libexec/java_home -v 1.8)
+export ANDROID_NDK=$ANDROID_SDK/ndk/21.0.6113669
+export HOST_TAG=darwin-x86_64
+export ANDROID_MIN_SDK_32=18
+export ANDROID_MIN_SDK_64=21
+export NDK_TOOLCHAIN=$ANDROID_NDK/toolchains/llvm/prebuilt/$HOST_TAG
+
+export PATH=$PATH:ANDROID_NDK/bin
+```
+
+## Add Rust android targets
+
+```bash
+rustup target add aarch64-linux-android armv7-linux-androideabi i686-linux-android x86_64-linux-android
+```
+
+Tell rust the location of the new target linker and AR
+
+```bash
+echo "
+[target.aarch64-linux-android]
+ar = \"$NDK_TOOLCHAIN/bin/aarch64-linux-android-ar\"
+linker = \"$NDK_TOOLCHAIN/bin/aarch64-linux-android$ANDROID_MIN_SDK_64-clang\"
+
+[target.armv7-linux-androideabi]
+ar = \"$NDK_TOOLCHAIN/bin/arm-linux-androideabi-ar\"
+linker = \"$NDK_TOOLCHAIN/bin/armv7a-linux-androideabi$ANDROID_MIN_SDK_32-clang\"
+
+[target.x86_64-linux-android]
+ar = \"$NDK_TOOLCHAIN/bin/x86_64-linux-android-ar\"
+linker = \"$NDK_TOOLCHAIN/bin/x86_64-linux-android$ANDROID_MIN_SDK_64-clang\"
+
+[target.i686-linux-android]
+ar = \"$NDK_TOOLCHAIN/bin/i686-linux-android-ar\"
+linker = \"$NDK_TOOLCHAIN/bin/i686-linux-android$ANDROID_MIN_SDK_32-clang\"
+" >> $HOME/.cargo/config
+
+```
+
+## Build it
+
+Open the android project with Android Studio, this will generate the file local.properties with the sdk location.
+
+To build can be done form the Gradle menu (on the right in android studio) and select the build task, or just calling gradle build form terminal.
+
+``` Bash
+gradle build #Run inside JNIAdapter/android
+```
+