Android Ndk

Download NDK

Here is the example in Linux.

ndkroot=~/ndk   # change the default directory if necessary
ndkver=10d
ndk=$ndkroot/android-ndk-r$ndkver

#
# Install NDK
# refer to https://developer.android.com/tools/sdk/ndk/index.html
#
ndk_install()
{
    mkdir -p $ndk
    cd $ndk
    ndkbin=android-ndk-r$ndkver-linux-x86_64.bin
    wget http://dl.google.com/android/ndk/$ndkbin
    chmod a+x $ndkbin
    ./$ndkbin

    export PATH=$PATH:$ndk/
}

#
# build sample code to test it
#
ndk_test()
{
    cd $ndk
    cd samples/hello-jni
    ndk-build
}

Build Applications with NDK

Application with jni/Android.mk

For example, the directory is as bellow:

samples/hello-jni/
.
├── AndroidManifest.xml
├── default.properties
├── jni
│   ├── Android.mk
│   ├── Application.mk
│   └── hello-jni.c

Just run:

ndk-build

Then, you can get the final results in ./libs

Application without jni directory

app
.
├── Android.mk
├── Application.mk
└── main.c

Then need set NDK_PROJECT_PATH(for output) and NDK_MODULE_PATH(for Android.mk). And can use -C to change the build directory first.

So, run as bellow:

ndk-build -C path/to/app NDK_MODULE_PATH=Android.mk NDK_PROJECT_PATH=out

It will use path/to/app/Android.mk to build, and output to out directory.

Note: NDK_APPLICATION_MK can be used to specified the Application.mk too.

NDK Standalone Toolchain

NDK Standalone Toolchain is for user to build applications as a pure gcc toolchain.

It is built as bellow.

cd ndk
./build/tools/make-standalone-toolchain.sh \
        --toolchain=arm-linux-androideabi-4.9 \
        --llvm-version=3.5 \
        --platform=android-21 \
        --install-dir=/home/chenys/ndk/ndk-chenys/

The direcroty structure:

tree -L 2
.
├── arm-linux-androideabi
│   ├── bin
│   └── lib
├── bin
│   ├── arm64-v8a
│   ├── armeabi
│   ├── armeabi-v7a
│   ├── armeabi-v7a-hard
│   ├── x86
│   └── x86_64
├── include
│   ├── c++
│   ├── gdb
│   └── python2.7
├── lib
│   ├── clang
│   ├── gcc
│   └── python2.7
├── lib64
├── libexec
│   └── gcc
├── share
│   └── gdb
├── SOURCES
└── sysroot
    └── usr

Use NDK to Simulate Android mm and mmm

put bellow scripts in build/envsetup.sh. And load it every time before start to build by

. build/envsetup.sh

build/envsetup.sh

TOP=`pwd`

function hmm() {
    cat <<EOF
    Invoke ". build/envsetup.sh" from your shell to add the following functions to your environment:
    - mm:      Builds all of the modules in the current directory, but not their dependencies.
    - mmm:     Builds all of the modules in the supplied directories, but not their dependencies.

    Look at the source to view more functions. The complete list is:
    EOF
        local A
        A=""
        for i in `cat $TOP/build/envsetup.sh | sed -n "/^function /s/function \([a-z_]*\).*/\1/p" | sort`; do
            A="$A $i"
        done
        echo $A
}

function setpaths()
{
    # setup ndk
    export ANDROID_NDK_PATH=$TOP/ndk/android-ndk-r10d/
    export ANDROID_NDK_TOOLCHAIN=$ANDROID_NDK_PATH/ndk-build
    export PATH=$PATH:$ANDROID_NDK_PATH
    # setup toolchain
    export ARM_EABI_TOOLCHAIN_PATH=$TOP/prebuilts/gcc/linux-x86/arm/arm-eabi-4.6/
    export PATH=$PATH:$ARM_EABI_TOOLCHAIN_PATH/bin
    export ARM_EABI_TOOLCHAIN=$ARM_EABI_TOOLCHAIN_PATH/bin/arm-ebi-
    # setup kernel
    export KDIR=$TOP/kernel/linux-3.10
    export ANDROID_PRODUCT_OUT=$TOP/out/
}
setpaths

function mmm()
{
    $ANDROID_NDK_TOOLCHAIN -C $1 APP_BUILD_SCRIPT=Android.mk NDK_PROJECT_PATH=$ANDROID_PRODUCT_OUT
}

function mm()
{
    mmm .
}

Reference

[1] https://developer.android.com/tools/sdk/ndk/index.html