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+# Building aapt binaries.
+
+The steps taken for building our modified aapt binaries for apktool.
+
+### Getting the modified `frameworks/base` repo.
+First step is using the [platform_frameworks_base](https://github.com/iBotPeaches/platform_frameworks_base) repo.
+
+While previously unorganized, the repo now follows the branch naming convention depending on the current Android version.
+So `apktool_7.1` corresponds to the 7.1 Android release. This branch should work for all `android-7.1.x` tags for AOSP.
+
+We didn't follow this naming convention until Android 7.1. So don't go looking for older versions.
+
+This repo has a variety of changes applied. These changes range from disabling optimizations to lessening the rules
+that aapt regularly has. We do this because apktool's job is to not fix apks, but rather keep them as close to the
+original as they were.
+
+### First we need the AOSP source
+
+As cheesy as it is, just follow this [downloading](https://source.android.com/source/downloading.html) link in order
+to get the source downloaded. This is no small download, expect to use 40-60GB.
+
+After that, you need to build AOSP via this [documentation](https://source.android.com/source/building.html) guide. Now
+we aren't building the entire AOSP package, the initial build is to just see if you are capable of building it.
+
+We check out a certain tag. Currently we use `android-7.1.1_r4`.
+
+### Including our modified `frameworks/base` package.
+
+There is probably a more automated way to do this, but for now just remove all the files in `frameworks/base`. Now
+you can clone the modified repo from first step into this directory.
+
+### Building the aapt binary.
+
+The steps below are different per flavor and operating system. For cross compiling the Windows binary on Unix,
+we lose the ability to quickly build just the aapt binary. So the Windows procedure builds the entire Sdk.
+
+#### Unix 32
+1. `source build/envsetup.sh`
+2. `lunch sdk-eng`
+3. `make OUT_DIR=out-x32 LOCAL_MULTILIB=32 USE_NINJA=false aapt`
+4. `strip out-x32/host/linux-x86/bin/aapt`
+
+#### Unix 64
+1. `source build/envsetup.sh`
+2. `lunch sdk-eng`
+3. `make OUT_DIR=out-x64 LOCAL_MULTILIB=64 USE_NINJA=false aapt`
+4. `strip out-x64/host/linux-x86/bin/aapt`
+
+#### Windows
+1. `source build/envsetup.sh`
+2. `lunch sdk-eng`
+3. `make PRODUCT-sdk-win_sdk USE_NINJA=false`
+4. `strip out/host/windows-x86/bin/aapt.exe`
+
+#### Mac 32
+1. `source build/envsetup.sh`
+2. `lunch sdk-eng`
+3. `make OUT_DIR=out-x32 LOCAL_MULTILIB=32 USE_NINJA=false aapt`
+
+#### Mac 64
+1. `source build/envsetup.sh`
+2. `lunch sdk-eng`
+3. `make OUT_DIR=out-x64 LOCAL_MULTILIB=64 USE_NINJA=false aapt`