MemoryIOTest
    allocateDirect/allocate

https://github.com/jnr/jnr-ffi/tree/master/libtest

void ptr_set_array_element(@Out Pointer[] array, int index, Pointer value);

ptr_set_array_element(void **ptrArray, int arrayIndex, void *value) {    
    ptrArray[arrayIndex] = value;
}

AddressByReferenceTest

public static interface TestLibOutOnly {
Address ptr_ret_pointer(@Out AddressByReference p, int offset);

https://github.com/jnr/jnr-ffi/blob/master/src/main/java/jnr/ffi/byref/AddressByReference.java

interface Lib {
    void get_a(@Out AddressByReference ap);
}

AddressByReference ap = new AddressByReference();
lib.get_a(ap);
System.out.println("a from lib=" + a.getValue());


https://github.com/jnr/jnr-ffi/blob/master/src/test/java/jnr/ffi/BufferTest.java

public static interface TestLib {
    void fillByteBuffer(@Out ByteBuffer buf, byte value, int size);
    void fillByteBuffer(@Out Buffer buf, byte value, int size);
    ...
}

https://github.com/jnr/jnr-ffi/blob/master/libtest/BufferTest.c


https://github.com/jnr/jnr-ffi/blob/master/libtest/ClosureTest.c

int testClosureNull(int (*closure)(void), int defaultValue)
{
    return closure ? (*closure)() : defaultValue;
}
void testClosureVrV(void (*closure)(void))
{
    (*closure)();
}

https://github.com/jnr/jnr-ffi/blob/master/src/test/java/jnr/ffi/DelegateTest.java

public static interface TestLib {
    public static interface CallableNull {
        @Delegate public int call();
    }
    int testClosureNull(CallableNull closure, int defaultValue);
    public static interface CallableVrV {
        @Delegate public void call();
    }
    void testClosureVrV(CallableVrV closure);
    public static interface CallableVrB {
        @Delegate public byte call();
    }
    ...
}