wrote:

From: user...@jna.dev.java.net <user...@jna.dev.java.net

Subject: users Digest 14 Mar 2009 11:45:27 -0000 Issue 267 To: use...@jna.dev.java.net Date: Saturday, March 14, 2009, 7:45 AM Hello List,

--------- ------- C++ code | ---> | Java --------- -------

I want my c++ function to return a c++ object instance, from my c++ code to java application ?

I didn't find any examples in documentation about this. I only read about primitive types. that's why I'm asking if it's possible with JNA.

Can anyone help me? Thanks in advance

Loïc

Please check ByteBuffer javadoc for more information regarding Direct and Non-Direct Buffers. ( http://java.sun.com/javase/6/docs/api/java/nio/ByteBuffer.html)<http://java.sun.com/javase/6/docs/api/java/nio/ByteBuffer.html

creates a non direct Buffer with the passed byte array a the backing array (meaning that when you read/write the buffer you are reading/writing the array. Use ByteBuffer.allocateDirect to create a direct buffer. Then use one of the put methods of ByteBuffer to write to the buffer. After checking jna documentation I believe, option 3 was not correct. From jna docs: "Primitive arrays and structures as members of a structure are overlaid on the parent structure memory." so it is not converted to a pointer that is what you need. Option 4 seem not to be supported, from the exception you are getting. Regarding the size of the image just try to print bytes.length. The memory should have that size, since that is the parameter you pass to the constructor.

Regards, Daniel

On Thu, Mar 12, 2009 at 9:34 AM, Drayton Brown <dray...@gmail.com>wrote:

work for non direct

Thanks Daniel your help has been most useful!

I believe that option 2 has worked out for me, although I think I will look into the direct buffer information you passed on as I believe I may be able to get some performance gains from it, as you expressed earlier.

Thanks once again,

Regards Drayton

2009/3/12 Daniel Kaufmann <dani...@gmail.com>

http://java.sun.com/javase/6/docs/api/java/nio/ByteBuffer.html)<http://java.sun.com/javase/6/docs/api/java/nio/ByteBuffer.html

creates a non direct Buffer with the passed byte array a the backing

not work for non direct

-- http://www.facebook.com/p/Drayton_Brown/517041504

Hello

I have to work with a DLL that controls a financial printer. The DLL was originally written for NT/Win31/Win95. There is a test program and that does not seem to work on Vista too as it shows com port not open error all the time.

When I try to use the functions from the DLL, I get unexpected return codes, e.g. 68 instead of 0.

Is it not possible to use 16 bit DLLs on XP/Vista? If it is possible, is there any thing wrong below?

Thanks in advance. avinash08820 ========================================= import com.sun.jna.Library; import com.sun.jna.Native; import com.sun.jna.NativeLibrary; import com.sun.jna.Platform; import com.sun.jna.win32.*;

public class TestPR2API { public interface PR2Communication extends Library{

PR2Communication pr2comm = (PR2Communication) Native.loadLibrary("wpr50nt", PR2Communication.class);

public byte PRT_CHECKHW (/*void*/); // It checks hardware. public byte PRT_RESET(/*void*/); //WORD WINAPI PRT_RESET (VOID);Performs a physical Reset of the machine. public byte PRT_EJECT(/*void*/); //WORD WINAPI PRT_EJECT (VOID);Eject the paper's front. public byte PRT_CLOSECOM (/*void*/); // Closes the communications port.

/* Functions with arguments */ public byte PRT_OPENCOM(SetupPR spr); public byte PRT_WRITE(String s, byte l); } public static void main(String[] args){

final char comport[] = {'C', 'O', 'M','1'};

SetupPR spr = new SetupPR();

spr.baud = 9600; spr.stop = 1; spr.parity = 'N'; spr.data = 8; //spr.port = comport; spr.port = "COM1"; byte actual = 0; //byte expected = 0;

actual = PR2Communication.pr2comm.PRT_OPENCOM(spr); System.out.println("returned = "+ actual); actual = PR2Communication.pr2comm.PRT_CHECKHW(); System.out.println("returned = "+ actual); actual = PR2Communication.pr2comm.PRT_EJECT(); System.out.println("returned = "+ actual);

actual = PR2Communication.pr2comm.PRT_RESET(); System.out.println("returned = "+ actual); String str = "Hello Hello";byte len = (byte)str.length(); actual = PR2Communication.pr2comm.PRT_WRITE(str,len);

} } ================================================================= import java.lang.String;

import com.sun.jna.Structure; import com.sun.jna.win32.StdCallLibrary;

public class SetupPR extends Structure { //public char port[] = {'C', 'O', 'M','1'}; public String port = "com1"; public short baud = 9600; public byte parity = 'N'; public byte data = 8; public byte stop = 1; } ================================================ The above maps typedef struct (_SETUPPR

CHAR CHAR Port[5]; Port [5]; Puerta (COM1 .. COMx) Puerta (COM1 .. COMx)

USHORT Ushort Baud; Baud; Velocidad (600 .. 9600) Speed (600 .. 9600)

BYTE BYTE Parity; Parity; Paridad (N=no, O=impar, E=par) Parity (N = no, O = odd, E = par)

BYTE BYTE Data; Data; Bits Data (7 ó 8) Data bits (7 or 8)

BYTE BYTE Stop; Stop; Bits Stop (1 ó 2) Stop bits (1 or 2)

} SETUPPR; SETUPPR);

It looks like you are not mapping it correctly the structure. I think it should be public class SetupPR extends Structure { public byte port[] = new byte[5]; public short baud = 9600; public byte parity = 'N'; public byte data = 8; public byte stop = 1; } and it looks like you should copy "COM1".getBytes() to port byte array and probably make sure that the last byte is 0 . Since 0 is the default value for byte, you won't need to do anything at all for that, just don't assign the result of "COM1".getBytes() because it will have only 5 bytes, make sure you copy the bytes to the array.

It looks like it is possible to call 16 bits library from 32bit code but doesn't seem to be easy. JNA just uses LoadLibrary but to load the dll but it looks that isn't enought, look at the following link: http://support.microsoft.com/kb/123731/en-us, looks like you need to use "Universal Thunk", but I am not sure what actually involves. Regards, Daniel

On Thu, Mar 12, 2009 at 7:09 PM, Avinash Kachhy <akac...@yahoo.com> wrote:

=================================================================

---------------------------------------------------------------------

Hello! first of all, thank you for JNA! i was trying to use SWIG before, and it was giving me so many problems. working with JNA is much more comfortable.

we have a native application from which we invoke the JVM. we use JNI for C->Java and JNA for Java->C communication. The main part of the Java->C communication works through a native struct, which is filled with function pointers. The Java/JNA wrapper class is both instantiated and then passed to a Java function with JNI. This worked well when we linked the application (its actually a plugin shared library used by the application) to the jvm with -ljvm. We found out, that this is not flexible enough for our needs, and we have to load the JVM dynamically now (eg. LoadLibrary() on windows, dlopen() on unix). since we do this, we always get a SIGSEGV when trying to create the callback with JNI. To make it short, i will describe what we do with JNI in mixed C/Java code, as this shortens the code a lot. [code] // C part ... const struct ClbStruct* myNativeClb = ...; Pointer clbStructP = new IntByReference((void*)myNativeClb).getPointer().getPointer(0); MyJNAClbWrapper clbWrp = MyJNAClbWrapper.getInstance(clbStructP);

// in Java ... class MyJNAClbWrapper extends Structure implements Structure.ByReference {

public static MyJNAClbWrapper getInstance(Pointer memory) {

MyJNAClbWrapper _inst = new MyJNAClbWrapper(); _inst.useMemory(memory); _inst.read(); return _inst; } ... } [/code] through debugging the java part, i found out that the SIGSEGV happens in the line with _inst.read(); and from the JNI log, i see thta the last method cammed is Memory.free(). I guess the problem lies there, as i can not see why any native memory should be freed here. the only thing involved is a const struct pointer, that contains only function pointers, and i only want JNA to read these addresses. Is there some way to tell JNA it shall not free anything? Or is my problem a different one?

I cant see why the dynamic loading of the JVM should cause such a difference. The only idea i have is that we are doing something wrong, and the dynamic loading (different use of memory maybe), converts the problem from a memory leack to a crash.

If this is not enough information, i can supply more; just tried to keep it as short as possible.

System Details: Ubuntu Linux 8.10 32bit SUN JDK 1.6.0_10 gcc 4.3.2 Intel Duo Hi all, Since my last emails, I've made numerous changes to JNAerator (errr... *improvements*, hopefully :-D), which I summarized on these two posts : JNAerator : global variables, automatic compilation (=> java 6) + many fixes<http://ochafik.free.fr/blog/?p=126> JNAerator v0.2 : Complex C declarators support and other fixes<http://ochafik.free.fr/blog/?p=125>

These changes include : - countless fixes (structures, typedefs...) - new alternative translations for functions, using java.nio.Buffer subclasses - constructors for structures - better parsing (complex C declarators, compiler-specific modifiers, retrieval of comments...) - generation of lazily-bound globals - fixes in JNAeratorStudio (can now type brackets, undo / redo, broken jnlp file : Launch JNAeratorStudio<http://ochafik.free.fr/Java/JNAeratorStudio.jnlp> )

I also wrote a page on the project's wiki that documents the JNAeration expectable output for various kinds of input : JNAerationResults<http://code.google.com/p/jnaerator/wiki/JNAerationResults

JNAerator is still rather buggy, so I'd be highly interested in your feedback on parsing issues and / or style of generated output (for now I'm trying to follow a one-fits-all approach, but I guess I'll have to provide more JNAeration options...).

Have fun ! Cheers