Hi,

Sorry for spamming, I got your email Id through JNA user group, my

scenario is a bit more complex thought of writing to you directly,

It would be great if you could give some hints on how to resolve

this issue:-

Right now facing problems with Callbacks, we have the following

scenario:-

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

C Code

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

typedef struct

{

WORD structure_size;

WORD parameter_code; /* Parameter code number. */

DWORD attributes_size; /* Size of following

attributes. */

void *attributes; /* Pointer to attributes.

Type of attributes inferred from parameter_code. */

} PARAMETER;

There is a callback which is globally declared in the JNI/C code:-

WORD LIBFUNC API_Callback(HSCANNER, MESSAGE, PARAM1, PARAM2 );

WORD LIBFUNC API_Callback(HSCANNER hengine, MESSAGE message, PARAM1

p1, PARAM2 p2)

{

WORD returnvalue = 0;

engineOutput * myEngineOutput;

printf("Message in Callback: %d" , message);

return returnvalue;

}

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

JNA MAPPING Code

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

public static class PARAMETER extends com.sun.jna.Structure {

/// Allocate a new PARAMETER struct on the heap

public PARAMETER () {}

/// Cast data at given memory location (pointer +

offset) as an existing PARAMETER struct

public PARAMETER (com.sun.jna.Pointer pointer, int

offset) {

super();

useMemory(pointer, offset);

read();

}

/// Create an instance that shares its memory with

another PARAMETER instance

public PARAMETER (PARAMETER struct)

{ this(struct.getPointer(), 0); }

public static class ByReference extends PARAMETER

implements com.sun.jna.Structure.ByReference {

/// Allocate a new PARAMETER.ByRef struct on

the heap

public ByReference() {}

/// Create an instance that shares its memory

with another PARAMETER instance

public ByReference(PARAMETER struct)

{ super(struct.getPointer(), 0); }

}

public static class ByValue extends PARAMETER

implements com.sun.jna.Structure.ByValue {

/// Allocate a new PARAMETER.ByVal struct on

the heap

public ByValue() {}

/// Create an instance that shares its memory

with another PARAMETER instance

public ByValue(PARAMETER struct)

{ super(struct.getPointer(), 0); }

}

public short structure_size;

/// Parameter code number.

public short parameter_code;

/// Size of following attributes.

public com.sun.jna.NativeLong attributes_size;

/// Pointer to attributes. Type of attributes inferred

from parameter_code.

public com.sun.jna.Pointer attributes; // Type this

can hold any data

}

/**

* Type of scanning engine callback function.<br>

*/

public interface CALLBACKTYPE_V1_callback extends

com.sun.jna.Callback {

/// Original signature : <code>LIBRET

CALLBACKTYPE_V1_callback(HSCANNER, MESSAGE, PARAM1, PARAM2_V1)</code>

short invoke(com.sun.jna.Pointer HSCANNER11, short

MESSAGE12, short PARAM113, com.sun.jna.NativeLong PARAM2_V114);

}

public class APICallbackImpl implements

TestLibrary.CALLBACKTYPE_V1_callback {

public short invoke(Pointer HSCANNER11, short MESSAGE12,

short PARAM113, NativeLong PARAM2_V114) {

return 123;///just for testing

}

}

Question:

How to set the pointer to the callback directly into PARAMETER

structure dynamically, we have a void* attributes field which is

used, in the current JNI implementation we have a MACRO which

actually adds the callback method pointer to this attributes field.

But how can we replicate this in JNA implementation?

Right now, it is a very critical issue and it is a showstopper for

us to proceed further, we browsed over and over again, but couldn't

find anything useful.

And also if possible, if you could give us how to debug JNA/C code

through eclipse or someother tool it would be helpful.

Thanks in advance! J

Regards,

JK

M: 9845955933

"If you are good at something, never do it for free!"