How to access $(TARGET_ARCH) from C++ file?

Issue

Using the Android NDK I'd like to know which target architecture is active when executing pre-processor code in my C++ header files. For example, my code would behave differently on "armeabi" vs. "armv7".

The $(TARGET_ARCH) variable can be used within makefiles, but is there an equivalent that's accessible from within C++ headers?

Thanks.

Solution

In addition to what Dan Albert posted, the hello-jni example actually already shows the necessary ifdefs for detecting the different ABIs:

https://github.com/googlesamples/android-ndk/blob/master/hello-jni/app/src/main/cpp/hello-jni.c

#if defined(__arm__)
    #if defined(__ARM_ARCH_7A__)
    #if defined(__ARM_NEON__)
      #if defined(__ARM_PCS_VFP)
        #define ABI "armeabi-v7a/NEON (hard-float)"
      #else
        #define ABI "armeabi-v7a/NEON"
      #endif
    #else
      #if defined(__ARM_PCS_VFP)
        #define ABI "armeabi-v7a (hard-float)"
      #else
        #define ABI "armeabi-v7a"
      #endif
    #endif
  #else
   #define ABI "armeabi"
  #endif
#elif defined(__i386__)
#define ABI "x86"
#elif defined(__x86_64__)
#define ABI "x86_64"
#elif defined(__mips64)  /* mips64el-* toolchain defines __mips__ too */
#define ABI "mips64"
#elif defined(__mips__)
#define ABI "mips"
#elif defined(__aarch64__)
#define ABI "arm64-v8a"
#else
#define ABI "unknown"
#endif

Answered By - mstorsjo