C-DLL function and huge pointer

After several tries I couldn't implement the following function found
in a C-DLL:

C- Code
// read a complete frame into buffer
      void _export VCVideoFrameRead(void huge *pBuf);

There seems to be problem when I translate it to the following Delphi
Pascal code:

Delphi- Code
// read a complete frame into buffer
      procedure VCVideoFrameRead(pBuf: Pointer); external 'VICAM32';

The data that is transferred from the Video Camera isn't placed in the
buffer that pBuf points to. Is there any solution or better way to
translate the 'huge *pBuf' c- code?

Video camera: compro internet camera
dll: Vicam32.DLL
Buffer: 640 X 480 X 24 bytes = 921600 bytes
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mheacockConnect With a Mentor Commented:
Try using the CDECL declaration:

   procedure Foo(x: Pointer); cdecl; external 'blah.dll';

If that doesn't work, then post the code you are using in
calling the DLL...where you actually pass the pointer and
how you set the pointer.
Did any of this help??  Can I be of further assistance??
sirk033097Author Commented:
Did you receive my additional info
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No...I don't see it here as a comment...did you get my e-mail
address from another question and mail me??  I hope not,
because I get a lot of mail and don't read all of it.
sirk033097Author Commented:
Procedure was already declared as cdecl
------------Converted C-Header
{/// read a complete frame into buffer }

procedure VCVideoFrameRead(pBuf: Pointer); cdecl; far;

------------Program call
  aryVideoBuffer = array[1..921600] of Byte;

procedure TfrmMain.TimerTimer(Sender: TObject);
      MemoryStream: TMemoryStream;
       VideoBuffer: aryVideoBuffer;
                pBuffer: Pointer;
      MemoryStream := TMemoryStream.Create;
      pBuffer := @VideoBuffer;
      for iCounter := 0 to High(VideoBuffer)-1 do begin
            MemoryStream.Write(VideoBuffer[iCounter],       MemoryStream.SaveToFile('c:\temp\test.bmp');

Have you tried:

   pBuffer := @VideoBuffer[0];
You might also try:


You might have to cast VideoBuffer to a pointer...


You've probably guessed correctly that I debug by trial and
error...its after I've gotten something working in this manner
that I then try and figure out why it worked.  Please tell me
the results of these.

I don't really see why it won't work the way you've got it now...is this a third-party DLL??  You are using Delphi 1.0,
I'm guessing and that the DLL is 16-bit.  What else...ummm...
if it is your own DLL, have you tried explicity declaring it
CDECL or maybe Pascal??
sirk033097Author Commented:
Small problem: I only see the answer you proposed the first time. Is there anyway I can have an overview of the answers-responses.
sirk033097Author Commented:
After adding a comment I get an overview of the question history  it would sure be handier it the program would do it the first time I visit the page instead of adding comments to see what has been going on.

I'll try your proposals.

Fyi. 32 bit third party C-DLL with only header file supplied. No source. All the other (non pointer) functions/procedures work fine but when I use function/procedures that use pointers nothing works (only the Exception handler). I'm using a Delphi 2.0 program to access the DLL. But since the other functions work properly I think the problem can be isolated to the pointer 'stuff'.
If it is a 3rd party DLL, use the STDCALL convention, unless
they explicitly tell you to use CDECL.  The majority of 32-bit
DLLs use the STDCALL convention...Microsoft recommends it.
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