More variables in NDK

NDK defines a few variables that can be automatically used in the Android.mk file.

TARGET_PLATFORM

This variable defines the target platform to be used by the build system:

TARGET_PLATFORM := android-21

The target is always used in the format android-xx. Not all the platform types are supported by NDK. It's a good idea to check on the NDK website which ones are supported. At the time of writing this book (1Q2016), this is the list of the supported platforms:

Supported NDK API level	Equivalent Android release
3	1.5
4	1.6
5	2.0
8	2.2
9	2.3 to 3.0.x
12	3.1.x
13	3.2
14	4.0 to 4.0.2
15	4.0.3 to 4.0.4
16	4.1 and 4.1.1
17	4.2 and 4.2.2
18	4.3
19	4.4
21	4.4W and 5.0

TARGET_ARCH

This variable specifies the architecture that will be used to build NDK. It could contain values such as x86 or arm. The value of this variable is taken from the APP_ABI file, which is specified in the Android.mk file. At the time of writing this book, this is the list of supported...