From 2c08fdb93ca7241f534df3a1c157f948e4e013ec Mon Sep 17 00:00:00 2001
From: Tom Finegan <tomfinegan@google.com>
Date: Thu, 26 Apr 2018 13:47:33 -0700
Subject: [PATCH] Add Android arm toolchains files.

---
 README.md                                     | 26 +++++++++++++++++++
 .../arm64-android-clang-libstdc++.cmake       | 18 +++++++++++++
 .../armv7-android-clang-libstdc++.cmake       | 18 +++++++++++++
 3 files changed, 62 insertions(+)
 create mode 100644 cmake/toolchains/arm64-android-clang-libstdc++.cmake
 create mode 100644 cmake/toolchains/armv7-android-clang-libstdc++.cmake

diff --git a/README.md b/README.md
index 83e382c..340a069 100644
--- a/README.md
+++ b/README.md
@@ -51,6 +51,7 @@ _**Contents**_
       * [Googletest Integration](#googletest-integration)
       * [Javascript Encoder/Decoder](#javascript-encoderdecoder)
     * [Android Studio Project Integration](#android-studio-project-integration)
+    * [Native Android Builds](#native-android-builds)
   * [Usage](#usage)
     * [Command Line Applications](#command-line-applications)
     * [Encoding Tool](#encoding-tool)
@@ -310,6 +311,31 @@ To add Draco to your project:
          }
      }
 
+Native Android Builds
+---------------------
+
+It's sometimes useful to build Draco command line tools and run them directly on
+Android devices via adb.
+
+~~~~~ bash
+# arm
+$ cmake path/to/draco -DCMAKE_TOOLCHAIN_FILE=path/to/draco/cmake/toolchains/armv7-android-clang-libstdc++.cmake
+$ make
+
+# arm64
+$ cmake path/to/draco -DCMAKE_TOOLCHAIN_FILE=path/to/draco/cmake/toolchains/arm64-android-clang-libstdc++.cmake
+$ make
+~~~~~
+
+Note: The above assumes that make_standalone_toolchain.py has been used to
+generate a standalone NDK toolchain for arm or arm64. In addition, Draco, as of
+this writing, requires that libc++ is used for the stl argument when the
+toolchain is generated.
+
+After building the tools they can be moved to an android device via the use of
+`adb push`, and then run with an `adb shell` instance.
+
+
 Usage
 ======
 
diff --git a/cmake/toolchains/arm64-android-clang-libstdc++.cmake b/cmake/toolchains/arm64-android-clang-libstdc++.cmake
new file mode 100644
index 0000000..919d271
--- /dev/null
+++ b/cmake/toolchains/arm64-android-clang-libstdc++.cmake
@@ -0,0 +1,18 @@
+if (NOT DRACO_CMAKE_TOOLCHAINS_ARM64_ANDROID_CLANG_LIBSTDCPP_CMAKE_)
+set(DRACO_CMAKE_TOOLCHAINS_ARM64_ANDROID_CLANG_LIBSTDCPP_CMAKE_ 1)
+
+set(CMAKE_SYSTEM_NAME "Linux")
+
+if ("${CROSS}" STREQUAL "")
+  # Default the cross compiler prefix to something known to work.
+  set(CROSS aarch64-linux-android-)
+endif ()
+
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+set(CMAKE_C_COMPILER ${CROSS}clang)
+set(CMAKE_CXX_COMPILER ${CROSS}clang++)
+set(CMAKE_EXE_LINKER_FLAGS  "${CMAKE_EXE_LINKER_FLAGS} -pie -static-libstdc++")
+set(AS_EXECUTABLE ${CROSS}as)
+set(CMAKE_SYSTEM_PROCESSOR "arm64")
+
+endif ()  # DRACO_CMAKE_TOOLCHAINS_ARM64_ANDROID_CLANG_LIBSTDCPP_CMAKE_
diff --git a/cmake/toolchains/armv7-android-clang-libstdc++.cmake b/cmake/toolchains/armv7-android-clang-libstdc++.cmake
new file mode 100644
index 0000000..5f8d9bd
--- /dev/null
+++ b/cmake/toolchains/armv7-android-clang-libstdc++.cmake
@@ -0,0 +1,18 @@
+if (NOT DRACO_CMAKE_TOOLCHAINS_ARMV7_ANDROID_CLANG_LIBSTDCPP_CMAKE_)
+set(DRACO_CMAKE_TOOLCHAINS_ARMV7_ANDROID_CLANG_LIBSTDCPP_CMAKE_ 1)
+
+set(CMAKE_SYSTEM_NAME "Linux")
+
+if ("${CROSS}" STREQUAL "")
+  # Default the cross compiler prefix to something known to work.
+  set(CROSS arm-linux-androideabi-)
+endif ()
+
+set(CMAKE_POSITION_INDEPENDENT_CODE ON)
+set(CMAKE_C_COMPILER ${CROSS}clang)
+set(CMAKE_CXX_COMPILER ${CROSS}clang++)
+set(CMAKE_EXE_LINKER_FLAGS  "${CMAKE_EXE_LINKER_FLAGS} -pie -static-libstdc++")
+set(AS_EXECUTABLE ${CROSS}as)
+set(CMAKE_SYSTEM_PROCESSOR "armv7")
+
+endif ()  # DRACO_CMAKE_TOOLCHAINS_ARMV7_ANDROID_CLANG_LIBSTDCPP_CMAKE_