Function pointers?

Does PL/SQL support the concept of function pointers like in C?
What I'd like to do is store procedure or function names in a table, select them into a variable and use the variable to call the procedure or function.
Joe

What you want is to read up on EXECUTE IMMEDIATE in the PL/SQL documentation.
Cheers, APC

Similar Messages

Problems Compiling Code With Function Pointers Using Sun CC (SUNWspro)

I have a header file that contains a declaration to a function pointer as follows:
int (*pFuncPntr)(char host, char comm, void *data);
Then, in a *.c file which includes the header file where the function pointer is declared, the prototype for the function is at the top of the file and appears as follows:
int someFunc(char hostname, char community, void *data);
Then, in the same *.c file, down below, I attempt to assign the function pointer to the address of the function declared as follows:
pFuncPntr = &someFunc;
... and further down in the *.c file is the definition of someFunc. ........................
When I compile, I get the following error:
: identifier redeclared: pFuncPntr
current : int
previous: pointer to function(pointer to char, pointer to char, pointer
to void) returning int : "/vobs/pp2dev/src/cmds/emcp_pmgmtd/sparc_solaris/../emc
p_pmgmtd.h", line 84
"/vobs/pp2dev/src/cmds/emcp_pmgmtd/sparc_solaris/emcp_pmgmtd_solaris.c", line 46
As far as I've read, this is the standard way of assigning a function pointer to the address of a function.
Does anyone have any ideas what CC compiler is complaining about?
Appreciate your response,
dedham_ma_man

WHen I try to include the ftp.jar package?? I use "package com.enterprisedt.net.ftp;".That isn't how you import a package. That declares that the class it is at the top of will belong to that package, and that's not what you want. I'm guessing that you need
import com.enterprisedt.net.ftp.*;
at the top of your code, just after the line where you declare the real name of the package your class is going to belong to.
By the way, you need the compiled version of your downloaded FTP code, i.e. the .class files. If you got source code (.java files) you'll need to compile them, but you should be able to get the compiled version as a download.

DLL import and Pointers to a function

Hi,
I am currently trying to get the ANT development kit working under LabView. For that i have imported the dllL (with the 8.2 version of LabView because of unknown reasons the import doesnt work under 8.5).
everything seems to work fine except one thing.
In the dll there is a function
void ANT_AssignResponseFunction(RESPONSE_FUNC pfResonse, UCHAR* pucResponseBuffer); // pucResponse buffer should be of size MESG_RESPONSE_EVENT_SIZE)
that needs a application callback function pointer as defined in the header (all files are attached)
// Application callback function pointer
typedef BOOL (*RESPONSE_FUNC)(UCHAR ucANTChannel, UCHAR ucResponseMsgID);
labview doesnt import the ANT_AssignResponseFunction propperly because it does not recognize RESPONSE_FUNC pfResonse. I have tried several things i have found in the forum and helpsites eg. with mathscript and so on but nothings working, and this and other functions that are built the same way need to work to read data... the example usage from the ant protocol in c looks like this
// Example Usage
BOOL ANT_ResponseFunction(UCHAR ucChannel, UCHAR ucResponseMesgID);
UCHAR aucResponseBuffer[MESG_RESPONSE_EVENT_SIZE];
ANT_AssignResponseFunction(&ANT_ResponseFunction, aucResponseBuffer);
but how can i get this working in labview? i have attached all files.
Please help me.
thanx a lot
martin
Attachments:
1204731171_ANT DLL 1_1.zip ‏77 KB
1204662412_ANT Message Protocol and Usage Rev 2.12.pdf ‏620 KB

martinboecskoer wrote:
hello,
thanks for the answeres. that the dll creation doesnt work with labview ist bad for me, cause my prog skills are very littel. has anyone a link to a good tutorial or so that can help me to create the wrapper dll.
If you don't know C already you would have a very steep learning curve. C in itself is already quite a bit to learn but pointers and expecially function pointers are another step higher in the knowledge ladder when learning C programming.
What is it for and can you afford to pay someone to do this for you? Because doing it yourself will certainly take you lots and lots of hours of work with an outcome that might appear to work but will quite likely crash under exotic curcumstances such as when you have shipped the entire applciation to the other side of the globe.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Assigning a variant string to a function pointer issue?

Hello,
This is a little complex for me to describe, so I will try my best to explain !
I don't know if this is doable in C?
Basically, I need a function pointer to hold the name of a function coming form a character array!
From the examples I have seen, it seems that what I am trying to do is not the conventional way of doing function pointers, but I don't see any other way of doing what I need to do.
In one instance, the function pointer in my code, will require to be assigned a function name like this:
_g_BlkFuncs_ =_BUF_FUNC_PTR_ParseBlockStatus;
and at other instances, the same function pointer needs to be assigned to a function called:
_g_BlkFuncs_ =_INV_FUNC_PTR_ParseBlockStatus;
and at other instances:
_g_BlkFuncs_ =_AND_FUNC_PTR_ParseBlockStatus;
or
_g_BlkFuncs_ =_OR_FUNC_PTR_ParseBlockStatus;
etc....
The only time I will know which function to assign is when I will retrieve the first part of the function name from a table called
_x_UserPrgBlock_. The first part being the name differentiator such as "_BUF_", "_INV_", "_AND_", "_OR_" and so forth which
is initially stored in the one of the table members called m_LogicElement_ residing in the _x_UserPrgBlock_ table or struct.
In the example below, I made it simple by hard coding the assigning of the m_LogicElement_ member as "_BUF_" (see the line commented as "Manual assignment line" below). In reality the m_LogicElement_ member is assigned from
a user defined string which will vary from time to time.
Here is the sample snippet which shows the issue.
================================STRUCT.h
#ifndef STRUCT_H
#define STRUCT_H
typedef struct USR_PRG_CNV{ // User program converter table
char m_LogicElement_[2][knst_BUF_LOGIC_ELEM]; // Name of the logic block
} User_Prg_Block;
#endif
=================================_BUF.h
#ifndef BUF_H
#define BUF_H
void _BUF_FUNC_PTR_ParseBlockStatus(void);
#endif
================================_BUF.c
void _BUF_FUNC_PTR_ParseBlockStatus(void){
int i = 0;
i = 10;
===============================UPC.h
#ifndef UPC_H
#define UPC_H
void AssignmentFunc();
#endif
===============================UPC.c
User_Prg_Block _x_UserPrgBlock_[2];
void AssignmentFunc(){
strcpy(_x_UserPrgBlock_[0].m_LogicElement_, "_BUF_"); // Manual assignment line
===============================DFP.c
#include "_BUF.h"
void (*_g_BlkFuncs_) (void);
char volatile _g_FuncPtrStrVariant_[35];
void SomeFunction(){
strcpy(_g_FuncPtrStrVariant_, _x_UserPrgBlock_[0].m_LogicElement_); // Get "_BUF_"
strcat(_g_FuncPtrStrVariant_, "FUNC_PTR_ParseBlockStatus"); // Complete the function name
// Now try to assign the full function name to the function pointer
//_g_BlkFuncs_ = _BUF_FUNC_PTR_ParseBlockStatus;
//_g_BlkFuncs_ = &_g_FuncPtrStrVariant_;
_g_BlkFuncs_ = _g_FuncPtrStrVariant_; // ???
==============================Main.c
void main(){
AssignmentFunc();
SomeFunction();
In reference to the following line listed above:
_g_BlkFuncs_ = _g_FuncPtrStrVariant_;
I do realize that conventionally, it should be:
_g_BlkFuncs_ =_BUF_FUNC_PTR_ParseBlockStatus;
The problem I find myself faced with is that the function that "_g_BlkFuncs_" points to, has to vary in accordance to the name of the function stored in the _g_FuncPtrStrVariant_ character array! The reason is that the _g_FuncPtrStrVariant_
array is actually built up to the name of the function based on the current contents of m_LogicElement_ residing in the _x_UserPrgBlock_ table.
I think!!!!! that even if I use an array of function pointers, it won't solve the issue.
In summary, in C, is there a way to assign a name of a function built from a character array to a function pointer?
All help sincerely appreciated!
Thanks

I am interpreting your question a little different than Brian.
If I understand you correctly you are asking: "Given the name of a function as a string, how do I get a pointer to that function".
The unfortunately fact is that C++ does not support reflection, so getting a function by name is not possible. By the time the linker has done its thing, the function name has been stripped from code.
This means if you need to support string lookup of a function name you need to support an alternate mechanism to handle this. If you were using C++, a map would be an ideal mechanism. C can still do this, but the mechanism is a lot uglier
due to the lack of data structures like std::string and std::map.

Pointer to void != pointer to function

Hello C experts,
this is a simple question about SunStudio's understanding of function pointers (it might have been asked before):
Why is the following C code giving me a warning on all Sun compilers:
# cat funcptr.c
int main() {
    void (*func)() = (void*)0;
    return 0;
# cc -c funcptr.c
"funcptr.c", line 2: warning: assignment type mismatch:
     pointer to function() returning void "=" pointer to voidIs the warning emitted by Sun compiler a bug (over-cautions). Other compiler's don't warn here.
Of course, I could use 0 or NULL as rvalue but I'm just wondering...
Jochen

Thanks everybody for your opinions.
@Stephen:
I wasn't aware that data pointers and function pointers may differ in any aspect. In fact, I only know data models that talk about 'pointer' width in general, like LP64 (64-bit wide long- and pointertypes), ILP32 (32-bit wide int-, long- and pointer-types), .. I'm especially surprised to hear that casting between data/function pointers will result in undefined behavior.
Anyway, to properly 'fix' the code above, I must cast the zero to a function pointer (with matching signature) instead of a void pointer. This compiles w/o a warning:
    void (*func)() = (void (*)())0;Thanks for clarification.
Jochen

When to use pointers in c++

I've recently started to get the hang off using c++. The only thing i'm having difficulty understanding is the use of pointers. I understand that pointers basically "point" to memory addresses of that variable. When should you start using pointers in your variables?
For example:
Without using a pointer i could just do:
myobject hello(1);
However i could also use a pointer to do just the same:
myobject* hello = new myobject(1);
With those 2 examples, you are basically creating a myobject named hello. Is there any difference between the pointer hello and the normal hello?
Last edited by dozerismydogsname (2010-04-30 03:05:10)

dozerismydogsname wrote:Is there any difference between the pointer hello and the normal hello?
The short answer: the object the pointer hello points to is allocated on the
heap, the normal hello is allocated on the stack. That means, after your current
block of code (enclosed in {}) ends, the normal hello will be destroyed while
the other one needs to be deleted by you using delete. If you don't delete it,
you'll get what is called a memory leak.
Whenever possible, you should use stack variables. When you need to use
pointers, you should really think about using std::auto_ptr or boost::shared_ptr
to prevent memory leaks as much as possible.
But I think your real question is this:
dozerismydogsname wrote:When should you start using pointers in your variables?
That question is far more difficult to answer. Usually, you tend to use pointers
if you start passing around arrays:
double sum (int n, const double* const numbers)
double result = 0.;
for (int i=0; i<n; ++i)
result += numbers[i];
return result;
However, this is C-style. In C++ you would try avoiding using pointers directly
by using encapsulating objects like such:
#include <vector>
double sum (const std::vector<double> numbers)
double result = 0.;
for (int i=0; i<numbers.size(); ++i)
result += numbers[i];
return result;
Which again saves you from thinking about who has to delete the pointer after
it's been used.
Often you want to use pointers to avoid copying large structures, but here you
typically can use references as well.
The only reasonable place in C++ I can currently think of to use pointers are
function pointers and places where you want to share structures (class or struct
instances) among several objects and want to be able to dynamically exchange
them. Again, you should use boost::shared_ptr here to avoid memory leaks. An
example:
class ReduceStrategy
public:
virtual double reduce (const double& a, const double& b) = 0;
protected:
ReduceStrategy ();
class SumStrategy : public ReduceStrategy
public:
SumStrategy ()
: ReduceStrategy() {}
virtual double reduce (const double& a, const double& b)
return a + b;
class SubtractStrategy [...]
class Reducer
public:
Reducer (boost::shared_ptr<ReduceStrategy> strategy)
: _strategy(strategy) {}
boost::shared_ptr<ReduceStrategy> strategy(new SumStrategy);
std::vector<Reducer> reducers;
for (int i=0; i<1000; ++i)
reducers.append(Reducer(strategy));
In this example, all 1000 Reducer instances share a pointer to the very same
ReduceStrategy object. If that object were very large now, you'd save a hell lot
of memory. Also, it would be possible to exchange the strategy for one, several
or all of the Reducer instances.
Wow, this text has become much longer than I originally intended^^ Hope it helps
at least a little.
Have fun learning C++!

How to access Call Back Functions using *.dll in the Labview?

Hai,
I am Pavan Ram Kumar Somu.
I am new to Labview, currently I am working on MVB Interface.
I need to access the API functions from *.dll file in Labview, as of now , I am doing this with Call function Library node in Labview but it does not support the following data types like
    1. Pointer Arguments(To which memory it points in Labview)
    2. function pointers Arguments
    3 .pointers in structures and pointer structures in structures and many other data types.
Please Answer the below queries also:
1. How to pass pointer arguments to API functions in DLL and how to collect pointer
    return types from API functions in DLL
2. How to pass structure arguments to API functions in DLL and how to collect structure
    return types from API functions in DLL
3. How to use callback functions(nothing but function pointers) in Labview and how to
    collect callback fuctions return types from API functions in DLL
I need your help while passing these datatypes to API functions in DLL from labview.
Suggest me if there is any other alternative for implementing this task.
I am referencing some examples here:
Examples:
I)
Unsigned short int gf_open_device(void *p_device_config, unsigned long int client_life_sign_timeout, unsigned short int *device_error)
void *p_device_config: How to access/pass these arguments in LabView and to which memory location it points in LabView.
II) #include <windows.h>
     #include <process.h>
     HANDLE rcvEvent0, rcvEvent1;
/* Function call*/
CanGetReceiveEvent(handle[0], &rcvEvent0);
Above is a piece of C code, Now I want to use HANDLE datatype which is windows based, how to use these type in the LABVIEW.
With regards
Pavan Ramu Samu

"Somu" <[email protected]> wrote in message news:[email protected]...
Hai,
I am Pavan Ram Kumar Somu.
 
I am new to Labview, currently I am working on MVB Interface.
 
I need to access the API functions from *.dll file in Labview, as of now , I am doing this with Call function Library node in Labview but it does not support the following data types like
    1. Pointer Arguments(To which memory it points in Labview)
    2. function pointers Arguments
    3 .pointers in structures and pointer structures in structures and many other data types.
 
Please Answer the below queries also:
 
1. How to pass pointer arguments to API functions in DLL and how to collect pointer  
    return types from API functions in DLL
 
2. How to pass structure arguments to API functions in DLL and how to collect structure
    return types from API functions in DLL
 
3. How to use callback functions(nothing but function pointers) in Labview and how to
    collect callback fuctions return types from API functions in DLL
 
I need your help while passing these datatypes to API functions in DLL from labview.
 
Suggest me if there is any other alternative for implementing this task.
 
 
I am referencing some examples here:
Examples:
I)
Unsigned short int gf_open_device(void *p_device_config, unsigned long int client_life_sign_timeout, unsigned short int *device_error)
 
void *p_device_config: How to access/pass these arguments in LabView and to which memory location it points in LabView.
 
II) #include <windows.h>
     #include <process.h>
   
     HANDLE rcvEvent0, rcvEvent1;
 
/* Function call*/
CanGetReceiveEvent(handle[0], &rcvEvent0);
 
Above is a piece of C code, Now I want to use HANDLE datatype which is windows based, how to use these type in the LABVIEW.
 
With regardsPavan Ramu Samu
Search the forum (forums.ni.com) for callback, pointer or handle, and you'll find that it is all possible, but not very easy.
e.g.: http://forums.ni.com/ni/board/message?board.id=170&message.id=88974&requireLogin=False
Regards,
Wiebe.

How to implement a callback function using LabView's Call Library Function Node?

I am trying to call a fuction from a SDK.dll library using the Call Library Function Node. The SDK was provided to
me and I do not have the source code, just the .dll and .h files.
The SdkSetPropertyEventHandler function has a callback fuction as one of its parameters. How do I implement the
callback using the CLF node? I am a good LabView programmer but this is my first time using the Call Library
Function Node. I have read all the info I can find on NI's web site and the discussion board but cannot figure
this one out. I am using LabView 8.6.
The SDK.h deacribes the function as:
// Function:   SdkSetPropertyEventHandler
SdkError SDKAPI SdkSetPropertyEventHandler(
            SdkCameraRef                    inCameraRef,
            SdkPropertyEvent                inEvnet,
            SdkPropertyEventHandler         inPropertyEventHandler,
            SdkVoid*                        inContext );
// Description:
//       Registers a callback function for receiving status
//          change notification events for property states on a camera.
// Parameters:
//       In:    inCameraRef - Designate the camera object.
//              inEvent - Designate one or all events to be supplemented.
//              inPropertyEventHandler - Designate the pointer to the callback
//                      function for receiving property-related camera events.
//              inContext - Designate application information to be passed by
//                      means of the callback function. Any data needed for
//                      your application can be passed.
//      Out:    None
// Returns:    Any of the sdk errors.
A separate header file called SDKTypes.h contains the following data:
typedef SdkUInt32 SdkPropertyEvent;
typedef SdkUInt32 SdkPropertyID;
typedef void       SdkVoid;
typedef struct __SdkObject*    SdkBaseRef;
typedef SdkBaseRef    SdkCameraRef;
SdkPropertyEventHandler
typedef SdkError ( SDKCALLBACK *SdkPropertyEventHandler )(
                    SdkPropertyEvent        inEvent,
                    SdkPropertyID           inPropertyID,
                    SdkUInt32               inParam,
                    SdkVoid *               inContext );
Thanks for your help.
Alejandro
Solved!
Go to Solution.

alejandroandreatta wrote:
I am trying to call a fuction from a SDK.dll library using the Call Library Function Node. The SDK was provided to
me and I do not have the source code, just the .dll and .h files.
The SdkSetPropertyEventHandler function has a callback fuction as one of its parameters. How do I implement the
callback using the CLF node? I am a good LabView programmer but this is my first time using the Call Library
Function Node. I have read all the info I can find on NI's web site and the discussion board but cannot figure
this one out. I am using LabView 8.6.
Basically you do not do that. LabVIEW does not know pointers and certainly not function pointers. What you should do instead is writing a C DLL that implements the callback and also exports a function to be called by LabVIEW that translates between the callback and a LabVIEW user event. Look for PostLVUserEvent() here on the NI site to find examples how to do that.
Rolf Kalbermatter
Message Edited by rolfk on 02-11-2009 08:00 PM
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

External Function with a Pointer to a Callback Function Inside a DLL

Hi.
I'm loading a DLL and trying to call a function with the following prototype:
Func1(HANDLE, hHandle, LPVOID (*pCallback)(UINT, UINT LPVOID), CHAR* sPath)
Now, I have no problem with the variable types, because CVI 9.0.1 recognizes all of them and I have no problem with LoadLibrary() nor with GetProcAddress().
But, how do I pass a pointer to a callback that is inside the DLL I'm trying to use.
I've tried to declare the callback like this:
LPVOID (CALLBACK Callback)(UINT iDevNo, UINT evEvent, LPVOID pData);
and call the function Func1 like this:
(Func1)(hHandle, &Callback, NULL);
but this gets me:
Undefined symbol '_Callback@12' referenced in "source.c".
Hope I can get some help.
I appreciate your time on this issue.
Regards.
Daniel Coelho
VISToolkit - http://www.vistoolkit.com - Your Real Virtual Instrument Solution
Controlar - Electronica Industrial e Sistemas, Lda
Solved!
Go to Solution.

Hi Daniel,
First, you have to make sure that the callback function is exported by the DLL, so that the program that uses the DLL can access the function name identifier. Then, you have to make sure that you call GetProcAddress not just on Func1, but also on the exported callback function. You need to store both function address values in their respective function pointers. You then can pass the callback function pointer as an argument to the Func1 call.
It's probably cleaner if you define typedefs for all your function pointers, in the calling program:
typedef LPVOID (__stdcall *CallbackType) (UINT , UINT, LPVOID);
typedef ??? (__stdcall *Func1Type) (HANDLE, hHandle, CallbackType, CHAR*);
CallbackType CallbackPtr;
Func1Type Func1Ptr;
dllHandle = LoadLibrary ("...");
CallbackPtr = (CallbackType)GetProcAddress (dllHandle, "Callback");
Func1Ptr = (Func1Type)GetProcAddress (dllHandle, "Func1");
Func1Ptr (..., hHandle, CallbackPtr, NULL);
Boa Sorte!
Luis

Function Pointer/Parent functionality in Java?

Hi,
I'm fairly new to Java and still finding my way around.
I have to write a game for a university project and need some functionality simalar to that of function pointers in C++. Basically, the game has several different types of objects (ships, planets, projectiles, etc). I have a class which runs a physics simulation, if I want an object to be included in the physics simulation, I instanciate a physics object class within that object and add a reference of the physics object to the physics simulator.
When the physics simulator detects a collision between two physics objects, i want the appropriate methods to be called within the two objects containing the physics objects. If i was using C++, i would simply construct each physics object with a function pointer to the method i want to run in the event of a collision.
I hope that made some sense...
Thankyou in advance for any input =)

If i was using C++But are you familiar with object-oriented programming? And Patterns?
Check out the Strategy Pattern: http://en.wikipedia.org/wiki/Strategy_pattern

Inline functions in C, gcc optimization and floating point arithmetic issues

For several days I really have become a fan of Alchemy. But after intensive testing I have found several issues which I'd like to solve but I can't without any help.
So...I'm porting an old game console emulator written by me in ANSI C. The code is working on both gcc and VisualStudio without any modification or crosscompile macros. The only platform code is the audio and video output which is out of scope, because I have ported audio and video witin AS3.
Here are the issues:
1. Inline functions - Having only a single inline function makes the code working incorrectly (although not crashing) even if any optimization is enabled or not (-O0 or O3). My current workarround is converting the inline functions to macros which achieves the same effect. Any ideas why inline functions break the code?
2. Compiler optimizations - well, my project consists of many C files one of which is called flash.c and it contains the main and exported functions. I build the project as follows:
gcc -c flash.c -O0 -o flash.o     //Please note the -O0 option!!!
gcc -c file1.c -O3 -o file1.o
gcc -c file2.c -O3 -o file2.o
... and so on
gcc *.o -swc -O0 -o emu.swc   //Please note the -O0 option again!!!
mxmlc.exe -library-path+=emu.swc --target-player=10.0.0 Emu.as
or file in $( ls *.o ) //Removes the obj files
    do
        rm $file
    done
If I define any option different from -O0 in gcc -c flash.c -O0 -o flash.o the program stops working correctly exactly as in the inline funtions code (but still does not crash or prints any errors in debug). flash has 4 static functions to be exported to AS3 and the main function. Do you know why?
If I define any option different from -O0 in gcc *.o -swc -O0 -o emu.swc the program stops working correctly exactly as above, but if I specify -O1, -O2 or O3 the SWC file gets smaller up to 2x for O3. Why? Is there a method to optimize all the obj files except flash.o because I suspect a similar issue as when compilling it?
3. Flating point issues - this is the worst one. My code is mainly based on integer arithmetic but on 1-2 places it requires flating point arithmetic. One of them is the conversion of 16-bit 44.1 Khz sound buffer to a float buffer with same sample rate but with samples in the range from -1.0 to 1.0.
My code:
void audio_prepare_as()
    uint32 i;
    for(i=0;i<audioSamples;i+=2)
        audiobuffer[i] = (float)snd.buffer[i]/32768;
        audiobuffer[i+1] = (float)snd.buffer[i+1]/32768;
My audio playback is working perfectly. But not if using the above conversion and I have inspected the float numbers - all incorrect and invalid. I tried other code with simple floats - same story. As if alchemy refuses to work with floats. What is wrong? I have another lace whre I must resize the framebuffer and there I have a float involved - same crap. Please help me?
Found the floating point problem: audiobuffer is written to a ByteArray and then used in AS. But C floats are obviously not the same as those in AS3. Now the floating point is resolved.
The optimization issues remain! I really need to speed up my code.
Thank you in advice!

Dear Bernd,
I am still unable to run the optimizations and turn on the inline functions. None of the inline functions contain any stdli function just pure asignments, reads, simple arithmetic and bitwise operations.
In fact, the file containing the main function and those functions for export in AS3 did have memset and memcpy. I tried your suggestion and put the code above the functions calling memset and memcpy. It did not work soe I put the code in a header which is included topmost in each C file. The only system header I use is malloc.h and it is included topmost. In other C file I use pow, sin and log10 from math.h but I removed it and made the same thing:
//shared.h
#ifndef _SHARED_H_
#define _SHARED_H_
#include <malloc.h>
static void * custom_memmove( void * destination, const void * source, unsigned int num ) {
void *result;
__asm__("%0 memmove(%1, %2, %3)\n" : "=r"(result) : "r"(destination), "r"(source), "r"(num));
return result;
static void * custom_memcpy ( void * destination, const void * source, unsigned int num ) {
void *result;
__asm__("%0 memcpy(%1, %2, %3)\n" : "=r"(result) : "r"(destination), "r"(source), "r"(num));
return result;
static void * custom_memset ( void * ptr, int value, unsigned int num ) {
void *result;
__asm__("%0 memset(%1, %2, %3)\n" : "=r"(result) : "r"(ptr), "r"(value), "r"(num));
return result;
static float custom_pow(float x, int y) {
    float result;
__asm__("%0 pow(%1, %2)\n" : "=r"(result) : "r"(x), "r"(y));
return result;
static double custom_sin(double x) {
    double result;
__asm__("%0 sin(%1)\n" : "=r"(result) : "r"(x));
return result;
static double custom_log10(double x) {
    double result;
__asm__("%0 log10(%1)\n" : "=r"(result) : "r"(x));
return result;
#define memmove custom_memmove
#define memcpy custom_memcpy
#define memset custom_memset
#define pow custom_pow
#define sin custom_sin
#define log10 custom_log10
#include "types.h"
#include "macros.h"
#include "m68k.h"
#include "z80.h"
#include "genesis.h"
#include "vdp.h"
#include "render.h"
#include "mem68k.h"
#include "memz80.h"
#include "membnk.h"
#include "memvdp.h"
#include "system.h"
#include "loadrom.h"
#include "input.h"
#include "io.h"
#include "sound.h"
#include "fm.h"
#include "sn76496.h"
#endif /* _SHARED_H_ */
It still behave the same way as if nothing was changed (works incorrectly - displays jerk which does not move, whereby the image is supposed to move)
As I am porting an emulator (Sega Mega Drive) I use manu arrays of function pointers for implementing the opcodes of the CPU's. Could this be an issue?
I did a workaround for the floating point problem but processing is very slow so I hear only bzzt bzzt but this is for now out of scope. The emulator compiled with gcc runs at 300 fps on a 1.3 GHz machine, whereby my non optimized AVM2 code compiled by alchemy produces 14 fps. The pure rendering is super fast and the problem lies in the computational power of AVM. The frame buffer and the enulation are generated in the C code and only the pixels are copied to AS3, where they are plotted in a BitmapData. On 2.0 GHz Dual core I achieved only 21 fps. Goal is 60 fps to have smooth audio and video. But this is offtopic. After all everything works (slow) without optimization, and I would somehow turn it on. Suggestions?
Here is the file with the main function:
#include "shared.h"
#include "AS3.h"
#define FRAMEBUFFER_LENGTH    (320*240*4)
static uint8* framebuffer;
static uint32 audioSamples;
AS3_Val sega_rom(void* self, AS3_Val args)
    int size, offset, i;
    uint8 hardware;
    uint8 country;
    uint8 header[0x200];
    uint8 *ptr;
    AS3_Val length;
    AS3_Val ba;
    AS3_ArrayValue(args, "AS3ValType", &ba);
    country = 0;
    offset = 0;
    length = AS3_GetS(ba, "length");
    size = AS3_IntValue(length);
    ptr = (uint8*)malloc(size);
    AS3_SetS(ba, "position", AS3_Int(0));
    AS3_ByteArray_readBytes(ptr, ba, size);
    //FILE* f = fopen("boris_dump.bin", "wb");
    //fwrite(ptr, size, 1, f);
    //fclose(f);
    if((size / 512) & 1)
        size -= 512;
        offset += 512;
        memcpy(header, ptr, 512);
        for(i = 0; i < (size / 0x4000); i += 1)
            deinterleave_block(ptr + offset + (i * 0x4000));
    memset(cart_rom, 0, 0x400000);
    if(size > 0x400000) size = 0x400000;
    memcpy(cart_rom, ptr + offset, size);
    /* Free allocated file data */
    free(ptr);
    hardware = 0;
    for (i = 0x1f0; i < 0x1ff; i++)
        switch (cart_rom[i]) {
     case 'U':
         hardware |= 4;
         break;
     case 'J':
         hardware |= 1;
         break;
     case 'E':
         hardware |= 8;
         break;
    if (cart_rom[0x1f0] >= '1' && cart_rom[0x1f0] <= '9') {
        hardware = cart_rom[0x1f0] - '0';
    } else if (cart_rom[0x1f0] >= 'A' && cart_rom[0x1f0] <= 'F') {
        hardware = cart_rom[0x1f0] - 'A' + 10;
    if (country) hardware=country; //simple autodetect override
    //From PicoDrive
    if (hardware&8)
        hw=0xc0; vdp_pal=1;
    } // Europe
    else if (hardware&4)
        hw=0x80; vdp_pal=0;
    } // USA
    else if (hardware&2)
        hw=0x40; vdp_pal=1;
    } // Japan PAL
    else if (hardware&1)
        hw=0x00; vdp_pal=0;
    } // Japan NTSC
    else
        hw=0x80; // USA
    if (vdp_pal) {
        vdp_rate = 50;
        lines_per_frame = 312;
    } else {
        vdp_rate = 60;
        lines_per_frame = 262;
    /*SRAM*/
    if(cart_rom[0x1b1] == 'A' && cart_rom[0x1b0] == 'R')
        save_start = cart_rom[0x1b4] << 24 | cart_rom[0x1b5] << 16 |
            cart_rom[0x1b6] << 8 | cart_rom[0x1b7] << 0;
        save_len = cart_rom[0x1b8] << 24 | cart_rom[0x1b9] << 16 |
            cart_rom[0x1ba] << 8 | cart_rom[0x1bb] << 0;
        // Make sure start is even, end is odd, for alignment
        // A ROM that I came across had the start and end bytes of
        // the save ram the same and wouldn't work. Fix this as seen
        // fit, I know it could probably use some work. [PKH]
        if(save_start != save_len)
            if(save_start & 1) --save_start;
            if(!(save_len & 1)) ++save_len;
            save_len -= (save_start - 1);
            saveram = (unsigned char*)malloc(save_len);
            // If save RAM does not overlap main ROM, set it active by default since
            // a few games can't manage to properly switch it on/off.
            if(save_start >= (unsigned)size)
                save_active = 1;
        else
            save_start = save_len = 0;
            saveram = NULL;
    else
        save_start = save_len = 0;
        saveram = NULL;
    return AS3_Int(0);
AS3_Val sega_init(void* self, AS3_Val args)
    system_init();
    audioSamples = (44100 / vdp_rate)*2;
    framebuffer = (uint8*)malloc(FRAMEBUFFER_LENGTH);
    return AS3_Int(vdp_rate);
AS3_Val sega_reset(void* self, AS3_Val args)
    system_reset();
    return AS3_Int(0);
AS3_Val sega_frame(void* self, AS3_Val args)
    uint32 width;
    uint32 height;
    uint32 x, y;
    uint32 di, si, r;
    uint16 p;
    AS3_Val fb_ba;
    AS3_ArrayValue(args, "AS3ValType", &fb_ba);
    system_frame(0);
    AS3_SetS(fb_ba, "position", AS3_Int(0));
    width = (reg[12] & 1) ? 320 : 256;
    height = (reg[1] & 8) ? 240 : 224;
    for(y=0;y<240;y++)
        for(x=0;x<320;x++)
            di = 1280*y + x<<2;
            si = (y << 10) + ((x + bitmap.viewport.x) << 1);
            p = *((uint16*)(bitmap.data + si));
            framebuffer[di + 3] = (uint8)((p & 0x1f) << 3);
            framebuffer[di + 2] = (uint8)(((p >> 5) & 0x1f) << 3);
            framebuffer[di + 1] = (uint8)(((p >> 10) & 0x1f) << 3);
    AS3_ByteArray_writeBytes(fb_ba, framebuffer, FRAMEBUFFER_LENGTH);
    AS3_SetS(fb_ba, "position", AS3_Int(0));
    r = (width << 16) | height;
    return AS3_Int(r);
AS3_Val sega_audio(void* self, AS3_Val args)
    AS3_Val ab_ba;
    AS3_ArrayValue(args, "AS3ValType", &ab_ba);
    AS3_SetS(ab_ba, "position", AS3_Int(0));
    AS3_ByteArray_writeBytes(ab_ba, snd.buffer, audioSamples*sizeof(int16));
    AS3_SetS(ab_ba, "position", AS3_Int(0));
    return AS3_Int(0);
int main()
    AS3_Val romMethod = AS3_Function(NULL, sega_rom);
    AS3_Val initMethod = AS3_Function(NULL, sega_init);
    AS3_Val resetMethod = AS3_Function(NULL, sega_reset);
    AS3_Val frameMethod = AS3_Function(NULL, sega_frame);
    AS3_Val audioMethod = AS3_Function(NULL, sega_audio);
    // construct an object that holds references to the functions
    AS3_Val result = AS3_Object("sega_rom: AS3ValType, sega_init: AS3ValType, sega_reset: AS3ValType, sega_frame: AS3ValType, sega_audio: AS3ValType",
        romMethod, initMethod, resetMethod, frameMethod, audioMethod);
    // Release
    AS3_Release(romMethod);
    AS3_Release(initMethod);
    AS3_Release(resetMethod);
    AS3_Release(frameMethod);
    AS3_Release(audioMethod);
    // notify that we initialized -- THIS DOES NOT RETURN!
    AS3_LibInit(result);
    // should never get here!
    return 0;

Call library function not finding DLL in directory where my LLBs are

I am using LabVIEW 8.6. I have a set of VIs in several LLBs. All the LLBs are in one directory. Most of my VIs are wrappers for the functions in one DLL. I was told to put my DLL in the directory where the LLBs are, and supposedly this is how the previous programmer worked (using an earlier version of LabView).
In the Call Library configuration, I have specified <dllname>.dll without a path. (This is how we want it as our VIs are an API which other programmers will integrate, so I don't know where they will put things and I can't use any absolute paths).
When I load the VIs in LabVIEW, LabVIEW can't find the DLL and asks me to located it. It is right there in the directory with the LLBs and when I double click on it everything works fine. However my absolute path to the DLL now appears in the Call library configuration, and we don't want that.
Does anyone know how to make this work? I would assume that the location of the VIs (or LLBs, in this case) would be the current directory and thus Windows would look there for the DLL. However, it seems that this is not the case (at least, in the current version of LabVIEW).
Thank you.
Batya
Solved!
Go to Solution.

rolfk wrote:
Well somebody using your library should not have to dig into your VIs and do all this on his own. Instead your library should wrap that and hide the troubles of this entirely.
That is EXACTLY what I want to do.
The error cluster was added when the dynamic path option was added. It is not useful to hide that error output so it is always there. Together with the dynamic path there was improved error handling added to the CLN. One of them is that the level of error checking during the function call (exception handling) can be specified. I would assume that some of those options can generate an error code instead of popping up a dialog as they did before and for that the error code output can be useful even in the static call case.
As to what you want to do, I would long ago
I would long ago have done a lot of things differently on this project -- but no one asked me then :-) (Good thing it wasn't me, or maybe I'd have taken offense ;-) )
have handled that with a wrapper DLL that has basically the same functions as your other DLLs and some initiliasation function that returns a pointer to a function dispatch structure based on the actual DLL you want to call.
OK, I am getting the feeling that this will be a brilliant and elegant solution when I fully understand it. I understand what a wrapper DLL is. But do you mean that each version of my product would include a different wrapper DLL (with the same name so that CLN would always work), or the same one and it would somehow be told which actual DLL I want to call? Who would decide which DLL, the VI or the wrapper DLL?
By a function dispatch structure do you mean a table of function pointers gotten by GetProcAddress, one such entry for each function?
Quite like what an object oriented function dispatch table is. Then when initilising your interface you call that initialise function and specify the interface/device type you want to use and after that all the other functions take one additional function dispatch pointer parameter as first parameter in addition to the parameters the actual function has. This function dispatch pointer would be just a pointer to a structure containing the table of function pointers for that interface and for the sake of LabVIEW would be simply a pointer sized integer.
The wrapper function then verifies the function dispatch structure pointer for validity and calls the actual function with the remaining parameters.
I think I understand what the wrapper functions need to do. But I am missing some pieces for the initialize function. It would have to do LoadLibrary and lots of GetProcAddresses -- that much I get. But I still don't understand who decides which DLL. Maybe you mean that the wrapper DLL's initialize function will get the DLL name and path from the registry, load it, try a different path if the load fails, etc. Is that what you mean? That could work very nicely. But from where would it get the registry key? From the VI? This is the part that would clearly be different for each product. I suppose that you had something in mind when you described your solution.
This is some C programming
Great! That's what I do for a living. At least I know how to do that! Hey, I should have thought of this idea!
and might require some planning and desigining of the different interfaces to facilitate this kind of dispatch technique but it will for sure pay of in the long run, and make your library even usable in earlier LabVIEW versions, as well as VB etc. without tricky dynamic loading in the high level programming environment.
Ah, see how much I don't know in LabVIEW? I didn't know this was a new feature...
Thank you for the great idea.
Batya Perlman

How can I handle function pointer in Java?

Is there any class/methods which can be used to implement function pointers in java.? If yes pliz, help me to get in.

The java equivalent of function pointers is the one-instance class, as used to pass handlers to swing components, for example. Often an anonymous class is used.
Put your function signature in an interface, and pass an object that implements that interface:
public Class1 {
public interface CallBack {
    void myMethod(String arg1);
CallBack callb;
public Class1(CallBack callb) {
   this.callb = callb;
callb.myMethod("A string");
class2 {
   first = new Class1(new Class1.CallBack() {
     public void myMethod(String arg1) {
       ... do something ...

How to call this dll point function by labview

Void SetCompStatusCallBack(void ((*CompStatusCallBack)(int id, int status, unsigned char conflict)))
Sets up callback function for getting component status.
Parameters:
* CompStatusCallback – entry point for callback function.
Return Value:
None.

left wrote:
Void SetCompStatusCallBack(void ((*CompStatusCallBack)(int id, int status, unsigned char conflict)))
Sets up callback function for getting component status.
Parameters:
* CompStatusCallback – entry point for callback function.
Return Value:
None.
You don't. This is the callback protoype that would be passed as parameter to another API and as such never will be called by the caller of that API but instead be provided by that caller!
And LabVIEW does not support function pointers at all, so you really can't do this.
The only solution is to write a wrapper function in your DLL or in a separate DLL that translates between this interface and some more event oriented LabVIEW functionality such as user events, but unless you do know C to a fairly good level, you should probably leave that to someone else.
Rolf Kalbermatter
Message Edited by rolfk on 01-26-2007 04:21 PM
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

CVI crashes when calling function from external DLL

I'm calling a CVI library from Test Stand 4.1. In that CVI library I load an external DLL (using LoadLibrary) and create a few function pointers (using GetProcAddress). The DLL loads successfully, and I get addresses for all of the imported functions.
However, when I one of the functions is called CVI crashes (Test Stand says it lost the ActiveX connection to CVI) when executing in an external CVI instance. If executed in the Test Stand process I get a system level exception.
If I step through the code in CVI, it hangs after trying to step into or over the call to the function pointer from the external DLL.
I am able to call the functions in a small test project I created in CVI, however when integrating it into an existing test library and calling it through Test Stand it fails.
Any ideas on how to go about debugging this issue?

Have you tried calling into the dll that CVI calls directly from TestStand? I am curious to know if this also crashes.
I am also curious to know if there are any path references in the dll that is called by the CVI program. If so are they relative, or absolute paths?
I ask because one of the possibilities is that relative paths are being used to specify a path from the location of the code that is called, and they are not working because the current working directory is being specified by TestStand, and the paths are not relative to the working directory given by TestStand.
Jensen
National Instruments
Applications Engineer

Function pointers?

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