Sync documents

docs/COMPILE.md

@@ -1,5 +1,7 @@
 This HOWTO introduces how to build Unicorn2 natively on Linux/Mac/Windows or cross-build to Windows from Linux host.
 
+Note: Please run `make clean` before you switch to `dev` branch.
+
 ## Native build on Linux/macOS
 
 This builds Unicorn2 on Linux/macOS. Note that this also applies to Apple Silicon M1 users.
@@ -9,24 +11,24 @@ This builds Unicorn2 on Linux/macOS. Note that this also applies to Apple Silico
 Ubuntu:
 
 ``` bash
-$ sudo apt install cmake pkg-config
+sudo apt install cmake pkg-config
 ```
 
 macOS:
 
 ```bash
-$ brew install cmake pkg-config
+brew install cmake pkg-config
 ```
 
 - Build with the following commands.
 
 ```bash
-$ mkdir build; cd build
-$ cmake .. -DCMAKE_BUILD_TYPE=Release
-$ make
+mkdir build; cd build
+cmake .. -DCMAKE_BUILD_TYPE=Release
+make
 ```
 
-### Native build on Windows, with MSVC
+## Native build on Windows, with MSVC
 
 This builds Unicorn2 on Windows, using Microsoft MSVC compiler.
 
@@ -42,31 +44,51 @@ nmake
 
 Note, other generators like `Ninja` and `Visual Studio 16 2019` would also work.
 
-```
+```bash
 mkdir build; cd build
 cmake .. -G "Visual Studio 16 2019" -A "win32" -DCMAKE_BUILD_TYPE=Release
 msbuild unicorn.sln -p:Plaform=Win32 -p:Configuration=Release
 ```
 
-### Cross build from Linux host to Windows, with Mingw
+## Cross build with NDK
+
+To build Unicorn2 on the Android platform, firstly you need to download [NDK](https://developer.android.com/ndk/downloads).
+
+For newer NDK, please make sure your cmake version is above 3.19.
+
+Then generate the project like:
+
+```bash
+mkdir build; cd build;
+cmake .. -DCMAKE_TOOLCHAIN_FILE=$NDK/build/cmake/android.toolchain.cmake -DANDROID_ABI=$ABI -DANDROID_NATIVE_API_LEVEL=$MINSDKVERSION
+make
+```
+
+You may get the possible values from this [page](https://developer.android.com/ndk/guides/cmake).
+
+Unicorn2 support cross-build for `armeabi-v7a`, `arm64-v8a`, `x86` and `x86_64`.
+
+Note the build is only tested and guaranteed to work under Linux, however, other systems may still work.
+
+## Cross build from Linux host to Windows, with Mingw
 
 This cross-builds Unicorn2 from **Linux host** to Windows, using `Mingw` compiler.
 
 - Install required package.
 
-```
-$ sudo apt install mingw-w64-x86-64-dev
+```bash
+sudo apt install mingw-w64-x86-64-dev
 ```
 
 - Build Unicorn and samples with the following commands.
 
-```
-$ mkdir build; cd build
-$ cmake .. -DCMAKE_TOOLCHAIN_FILE=../mingw64-w64.cmake
-$ make
+```bash
+mkdir build; cd build
+cmake .. -DCMAKE_TOOLCHAIN_FILE=../mingw64-w64.cmake
+make
 ```
 
-### Native build on Windows host, with MSYS2/Mingw
+## Native build on Windows host, with MSYS2/Mingw
 
 This builds Unicorn2 on **Windows host**, using **MSYS2/Mingw** compiler.
 
@@ -74,13 +96,13 @@ This requires MSYS2 to be installed on the Windows machine. You need to download
 
 Then from MSYS2 console, install packages below:
 
-```
+```bash
 pacman -S mingw-w64-x86_64-toolchain mingw-w64-x86_64-cmake
 ```
 
 - Build Unicorn and samples with the following commands.
 
-```
+```bash
 mkdir build; cd build
 /mingw64/bin/cmake .. -G "MSYS Makefiles" -DCMAKE_C_COMPILER=/mingw64/bin/gcc.exe -DCMAKE_MAKE_PROGRAM=/mingw64/bin/mingw32-make.exe -DCMAKE_AR=/mingw64/bin/ar.exe -DUNICORN_ARCH=x86
 mingw32-make
@@ -88,20 +110,20 @@ mingw32-make
 
 Note that the way to build on MSYS changes as time goes, please keep in mind that always use the cmake shipped with mingw64 and choose MSYS Makefiles.
 
-### Cross build from Linux host to other architectures
+## Cross build from Linux host to other architectures
 
 This cross-builds Unicorn2 from **Linux host** to other architectures, using a cross compiler.
 
 - Install cross compiler package. For example, cross-compile to ARM requires the below command.
 
-```
-$ sudo apt install gcc-arm-linux-gnueabihf
+```bash
+sudo apt install gcc-arm-linux-gnueabihf
 ```
 
 - Build Unicorn and samples with the following commands. The compiler name differs according to your targets.
 
-```
-$ mkdir build; cd build
-$ cmake .. -DCMAKE_C_COMPILER=gcc-arm-linux-gnueabihf
-$ make
+```bash
+mkdir build; cd build
+cmake .. -DCMAKE_C_COMPILER=gcc-arm-linux-gnueabihf
+make
 ```