title: when to use JNIEXPORT and JNICALL in Android NDK?
body: <p>I'm trying to write my own jni sources. Looking at some ndk samples, I found that they often use those macros JNIEXPORT and JNICALL follewed by the name of java package like this </p>
  
  <p><code>JNIEXPORT void JNICALL Java_com_example_plasma_PlasmaView_renderPlasma(JNIEnv * env, jobject  obj, jobject bitmap,  jlong  time_ms)
  </code></p>
  
  <p>I googled it but I can't understand when and how to use these macros </p>