http://jonisalonen.com/2012/calling-c-from-java-is-easy/ http://jonisalonen.com/2012/runtime-exec-with-unix-console-programs/
no Javah from Java9 https://docs.oracle.com/javase/9/tools/javah.htm#JSWOR687 https://stackoverflow.com/questions/46577196/javac-no-source-files-when-using-h-option
https://www.chilkatsoft.com/java-loadLibrary-Linux.asp
very good one https://www3.ntu.edu.sg/home/ehchua/programming/java/JavaNativeInterface.html
https://stackoverflow.com/questions/4936492/jni-freeing-primitive-arrays-and-out-of-memory-exceptions https://stackoverflow.com/questions/5231599/is-there-any-way-to-pass-a-java-array-to-c-through-jni-without-making-a-copy-of https://docs.oracle.com/javase/1.5.0/docs/guide/jni/spec/functions.html#GetDirectBufferAddress https://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/functions.html#GetDirectBufferAddress https://stackoverflow.com/questions/29745584/using-getdirectbufferaddress-from-jni https://stackoverflow.com/questions/23258357/whats-the-trade-off-between-using-getprimitivearraycritical-and-getprimitivety
https://www.google.com/search?q=java+convert+array+to+bytebuffer&oq=java+convert+array+to+bytebuffer&aqs=chrome..69i57j0l3.14629j0j7&sourceid=chrome&ie=UTF-8 http://www.java2s.com/Tutorials/Java/Data_Type/Double/Convert_double_to_byte_array_in_Java.htm
https://www.math.uni-hamburg.de/doc/java/tutorial/native1.1/implementing/array.html