Calling a PB DLL from a Delphi EXE

[Todd Wasson]

Hello,
I'm working via email with a Delphi/Pascal programmer on a project.
His Delphi program will be calling my PowerBasic DLL, but we're having
a heck of a time getting a simple function to work! (We're both ignorant,
I guess ) As a test, he'd like to call my DLL to perform a division
on two LONGS (32 bit LONGS are called "integers" in Delphi) and return
a SINGLE.

His Delphi version of the DLL call is:

function TestIntDiv(a,b: integer): single; stdcall; external 'DLLTEST.DLL';

I'll show more of his DLL source if it would help, but it doesn't look
like much of it has to do with this function (I could easily be wrong again
though, of course.)


Here's my PB DLL:

#COMPILE DLL

FUNCTION TestIntDiv (a AS LONG,b AS LONG) EXPORT AS SINGLE
   MSGBOX "PowerBasic DLL Message: Input values are " + STR$(a)+" and " +STR$(b)
   FUNCTION=a/b 
END FUNCTION

I've tried this with INTEGER as well as LONG here, with the same
error message:

"The TESTDIVONLY.EXE file is linked to missing export DLLTEST.DLL
-TestIntDiv."

AARGH!! Anyone happen to know what may be wrong, or what this fellow
and I should be looking for? I saw this same error message in a search
through the forum, but it was for a PB EXE calling a Delphi DLL, rather
than the other way around.

Thanks a ton, I'd be lost without the help here on the PowerBasic forum!

Todd Wasson




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

[Don Dickinson]

Here's what your PB dll should look like ...

#COMPILE DLL
FUNCTION TestIntDiv Alias "TestIntDiv" _
   (ByVal a AS LONG, ByVal b AS LONG) EXPORT AS SINGLE   

  MSGBOX "PowerBasic DLL Message: Input values are " + _
    STR$(a)+" and " +STR$(b)   
  FUNCTION=a/b 

END FUNCTION

The Delphi declare should look like this (you had it right):

function TestIntDiv(a,b: integer): single; stdcall; external 'DLLTEST.DLL';

In short, delphi passes variables ByVal as a default (PB passes them ByRef). Also, your delphi app wasn't finding the entry point because you didn't specify the alias - it would have found TESTINTDIV, but then would have gpf'd because of the byval thing.
Best Regards
Don

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

[Todd Wasson]

Don,

Thank you! Fantastic! Such a quick reply too! I never would have
figured that out on my own. Just curious, I'll be testing the DLL during
development with a PB program. Should I (or can I) pass parameters and
work things the same way? How so? Make sure to use ALIAS in the Function
names with "BYVAL x SINGLE" for everything?

Thanks again!

Todd Wasson


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

[Don Dickinson]

Yes, you can. The one exception is when returning a string. Here's what I do ...

Global g_Return as String

'- Call this one from PB or VB
Function ReturnString Alias "ReturnString" _
    ( ByVal sString as String) Export as String
  Function = "This is the string: " + Trim$(sString)
End Function

'- Call this one from delphi
Function ReturnStringZ Alias "ReturnStringZ" _
    ( incoming as Asciiz) Export as DWORD
  g_Return = ReturnString(Trim$(incoming)) + $NUL
  Function = StrPtr(g_Return)
End Function

// The delphi declaration
function ReturnStringZ(zString : PChar) : PChar; stdcall; external 'mydll.dll';

'- The vb declaration
declare Function ReturnString Alias "ReturnString" _
    ( ByVal sString as String) as String

Or something like that. I didn't test it, but I think it's ok.

Best Regards,
Don

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

[Don Dickinson]

Also, I should point out that you can pass variable by reference as well. E.G.

#COMPILE DLL
'
'- When this returns, a will increase by one.
FUNCTION TestIntDiv Alias "TestIntDiv" _   
  (a AS LONG, b AS LONG) EXPORT AS SINGLE
   a = a + 1
     MSGBOX "PowerBasic DLL Message: Input values are " + _    
     STR$(a)+" and " +STR$(b)     
  FUNCTION=a/b 
END FUNCTION
'
'Te Delphi declare should look like this:
'
function TestIntDiv(var a: integer; var b : Integer): single; stdcall; external 'DLLTEST.DLL';

Best Regards,
Don


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

[Krister Olsson]

Don or any other Delphi expert,

I have a PB/DLL ver 6.0 DLL HX2000.DLL with a sub Get_Calculation:

'**************
SUB Get_Calculation(B1 AS BYTE, B2 AS BYTE, HeatexIn AS DOUBLE, sHeatexType AS ASCIIZ, B3 AS BYTE, B4 AS BYTE, HeatexOut AS DOUBLE) EXPORT

DIM HeatexInArray(20) AS DOUBLE
DIM HeatexOutArray(50) AS DOUBLE
DIM i AS LONG
DIM j AS LONG
DIM VvxDataIn AS DOUBLE Pointer
DIM VvxDataOut3 AS DOUBLE Pointer

'more code

VvxDataIn=VARPTR(HeatexIn)
FOR i=0 TO 20
HeatexInArray(i)=@VvxDataIn[i]
NEXT i


'much more code

VvxDataOut3=VARPTR(HeatexOut)
FOR j=0 TO 50
@VvxDataOut3[j] = HeatexOutArray(j)
NEXT j

'more code

END SUB
'***************

How do I declare and call Get_Calculation from Delphi?


Krister Olsson

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

[Fredrik Nilsson]

Old thread, by I have the same question as Krister

Best Regards
Fredrik

Don or any other Delphi expert,

I have a PB/DLL ver 6.0 DLL HX2000.DLL with a sub Get_Calculation:

'**************
SUB Get_Calculation(B1 AS BYTE, B2 AS BYTE, HeatexIn AS DOUBLE, sHeatexType AS ASCIIZ, B3 AS BYTE, B4 AS BYTE, HeatexOut AS DOUBLE) EXPORT

DIM HeatexInArray(20) AS DOUBLE
DIM HeatexOutArray(50) AS DOUBLE
DIM i AS LONG
DIM j AS LONG
DIM VvxDataIn AS DOUBLE Pointer
DIM VvxDataOut3 AS DOUBLE Pointer

'more code

VvxDataIn=VARPTR(HeatexIn)
FOR i=0 TO 20
HeatexInArray(i)=@VvxDataIn[i]
NEXT i


'much more code

VvxDataOut3=VARPTR(HeatexOut)
FOR j=0 TO 50
@VvxDataOut3[j] = HeatexOutArray(j)
NEXT j

'more code

END SUB
'***************

How do I declare and call Get_Calculation from Delphi?


Krister Olsson

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

[Michael Mattias]

>Make sure to use ALIAS in the Function names with "BYVAL x SINGLE" for everything

Um, the ALIAS in your PB Function header is used to specify the "export name" of the procedure, the name you use in your "using module's definition of that exported procedure"

It has nothing to do with parameter or return data types.

If you are going to be working "cross language" you may want to download and compile....

Show exports and imports for PB/Win 6x, 7x (original by Torsten Reinow)

You "open" your calling module and look in the "imports" ... that will be the name that module is looking for. You "open" your DLL module and check the "exports"... that gives you the name of your procedure as other programs must look for it.

IMPORT and EXPORT names ARE case-sensitive.

[Chris Holbrook]

No Delphi/Pascal code shown. Which compiler are you using?

If you are using a Windows unit you can use LoadLibrary/GetProcaddress.

[Todd Wasson]

Wow, I just an email reply from this thread I started more than 11 years ago... Thanks for the blast from the past. This was the very first line of code written as a test for what has since become this:

http://www.youtube.com/watch?v=RaMMa_X-PZ8

Sorry I can't help with your Delphi question. I'm sure one of these guys will help sort things out.

[Paul D. Elliott]

Sorry but may we have a real compilable version of the PB code to work with?

Do PB Doubles take up 21 bytes?
as in :

VvxDataIn=VARPTR(HeatexIn)
 FOR i=0 TO 20
 HeatexInArray(i)=@VvxDataIn[i]
 NEXT i

[Fredrik Nilsson]

Delphi code (IDE XE2) trying to call DLL:
(see attached error message)

procedure TForm1.Button1Click(Sender: TObject);
type
Short = Byte;
pShort = ^Short;
TArrayIn = packed array [0..20] of Double;
TArrayOut = packed array [0..50] of Double;
var
s1, s2: Byte;
z1, z2: pShort;
RRIN: TArrayIn;
RROUT: TArrayOut;
RRName: PAnsiChar;
v1: Integer;
Hbar: Thandle;
// Declaration. ***
GET_CALCULATION: procedure(_s1, _s2: Byte; _RRIN: TArrayIn; _RRName: PAnsiCHar; _z1, _z2: pShort; var RROUT_: TarrayOut);stdcall;
begin
Hbar := LoadLibrary('C:\Heatex32.dll');
if Hbar > 0 then
begin
try
try
GET_CALCULATION := GetProcAddress(Hbar, PAnsiChar('GET_CALCULATION'));
if Assigned(GET_CALCULATION) then
begin
// ***
s1 := 0;
s2 := 0;
// ***
for v1 := Low(RRIN) to High(RRIN) do
begin
RRIN[v1] := 0;
end;
RRIN[1] := 2.5;
RRIN[2] := 0;
RRIN[3] := 20;
RRIN[4] := 0.006;
RRIN[5] := 2.5;
RRIN[6] := 0;
RRIN[7] := -10;
RRIN[8] := 0.0016;
RRIN[9] := 1.2;
RRIN[10] := 1;
RRIN[11] := 1001;
RRIN[12] := 0;
RRIN[13] := 101325;
RRIN[14] := 0;
RRIN[15] := 0;
RRIN[16] := 0;
RRIN[17] := 0;
// ***
RRName := PAnsiChar('H0750/6.0/E');
// ***
GetMem(z1, SizeOf(Byte));
z1^ := 0;
GetMem(z2, SizeOf(Byte));
z2^ := 0;
// ***
for v1 := Low(RROUT) to High(RROUT) do
begin
RROUT[v1] := 0;
end;
// Call procedure. ***
GET_CALCULATION(s1, s2, RRIN, RRName, z1, z2, RROUT);
// Show result. ***
ShowMessage(FloatToStr(RROUT[0]));
end;
except
RaiseLastOSError;
end;
finally
FreeLibrary(HBar);
end;
end
else
begin
MessageDlg('Error: Can't find Heatex32.dll', mtError, [mbOk], 0);
end
end;

end.

No Delphi/Pascal code shown. Which compiler are you using?

If you are using a Windows unit you can use LoadLibrary/GetProcaddress.

[Chris Holbrook]

Making assumptions because I don't have PB/DLL V6 that the default is CDECL/STDCALL, and all parameters are passed BYREF.

So you want to supply pointers as arguments. I'm pretty sure that passing a byte is not the same as passing a pointer to a byte. Presumably VAR takes out a level of indirection too, so you have alternative methods of passing a pointer. Personally, I would use explicit pointers (pByte, pAnsiChar, etc), which would mean either declaring a pointer-to-your-double-array type or using a dword to pass the double array addresses. That may appear heavy-handed but it does show the next programmer to read your code exeactly what your intentions were!

If you have the PB/DLL or a PBWIn compiler you can create a DLL in minutes with SUBS/FUNCTIONS to test that each each individual argument type is passed correctly.

[Paul D. Elliott]

Is there any documentation on the interface for this DLL?
Any chance of seeing any code that DOES talk to it now?

Never mind. found

http://www.powerbasic.com/support/pbforums/showthread.php?p=151082

so will look at that for a while.

[Paul D. Elliott]

Ok, it's not pretty and am not sure which way sHeatexType is supposed to go.
and the arrays aren't in the 2004 thread. I based the DLL on what was in that thread.
and used Delphi v7 for the below code.
but the compiler is doing most of the work.

function GET_CALCULATION(var B1: byte; var B2: Byte; var HeatexIN: double; var sHeatexType: PAnsiCHar; var B3: byte; var B4: byte; var HeatexOut: double): integer; stdcall; external 'E:\pbcc\junk\Delphitst.DLL';


procedure TForm1.Button2Click(Sender: TObject);
type
 Short = Byte;
 pShort = ^Short;
 TArrayIn = packed array [0..20] of Double;
 TArrayOut = packed array [0..50] of Double;
var
 B1, B2, B3, B4: byte;
 HeatexIn: double; //TArrayIn;
 HeatexOut: double; //TArrayOut;
 sHeatexType: PAnsiChar;
 begin

 B1 := 65;
 B2 := 66;
 B3 := 67;
 B4 := 68;
 sHeatexType := 'HeatexType';
 HeatexIn := 1234.99;
 HeatexOut := 4321.88;
 edit4.Text := format('%d', [B1]);
 edit5.Text := format('%d', [B2]);
 edit6.Text := format('%d', [B3]);
 edit7.Text := format('%d', [B4]);
 edit8.Text := sHeatexType;
 edit9.Text := format('%f', [HeatexIn]);
 edit10.Text := format('%f', [HeatexOut]);

 GET_CALCULATION(B1, B2, HeatexIn, sHeatexType, B3, B4, HeatexOut);

 edit11.Text := format('%d', [B1]);
 edit12.Text := format('%d', [B2]);
 edit13.Text := format('%d', [B3]);
 edit14.Text := format('%d', [B4]);
 edit15.Text := sHeatexType;
 edit16.Text := format('%f', [HeatexIn]);
 edit17.Text := format('%f', [HeatexOut]);

end;

[Michael Mattias]

>(see attached error message)

0xC0000005 = attempt to access unowned memory. Best guess you passed a paremeter as an address when a value was required or vice-versa; or passed a PB STRING datatype when the Deplhi says STRING but which actually means BYREF ASCIIZ.

Then again you may have a programming error independent of the data types.

As Mr. Holbrook suggests, FIRST make sure your datatypes are being passed correctly.

[Paul D. Elliott]

fixed sHeaterType to go both ways if needed.
made HeatexIn & HeatexOut to be arrays.
fixed declaration so no return value expected ( same as Sub in PB ).

  procedure GET_CALCULATION(var B1: byte; var B2: Byte; var HeatexIN: double; sHeatexType: pAnsiChar; var B3: byte; var B4: byte; var HeatexOut: double); stdcall; external 'E:\pbcc\junk\Delphitst.DLL';

procedure TForm1.Button2Click(Sender: TObject);
type
 Short = Byte;
 pShort = ^Short;
 TArrayIn = packed array [0..20] of Double;
 TArrayOut = packed array [0..50] of Double;
var
 B1, B2, B3, B4: byte;
 HeatexIn: TArrayIn;
 HeatexOut: TArrayOut;
 sHeatexType: array [0..100] of char; //pAnsiChar;
 v1: integer;
 begin

 B1 := 65;
 B2 := 66;
 B3 := 67;
 B4 := 68;
 sHeatexType := 'HeatexType';

 For v1 := Low(HeatexIn) To High(HeatexIn) Do
  Begin
     HeatexIn[v1] := 0;
  End;
 HeatexIn[1] := 2.5;
 HeatexIn[2] := 0;
 HeatexIn[3] := 20;
 HeatexIn[4] := 0.006;
 HeatexIn[5] := 2.5;
 HeatexIn[6] := 0;
 HeatexIn[7] := -10;
 HeatexIn[8] := 0.0016;
 HeatexIn[9] := 1.2;
 HeatexIn[10] := 1;
 HeatexIn[11] := 1001;
 HeatexIn[12] := 0;
 HeatexIn[13] := 101325;
 HeatexIn[14] := 0;
 HeatexIn[15] := 0;
 HeatexIn[16] := 0;
 HeatexIn[17] := 0;

 For v1 := Low(HeatexOut) To High(HeatexOut) Do
   Begin
     HeatexOut[v1] := 0;
   End;

 HeatexIn[0] := 1234.99;
 HeatexOut[0] := 4321.88;
 edit4.Text := format('%d', [B1]);
 edit5.Text := format('%d', [B2]);
 edit6.Text := format('%d', [B3]);
 edit7.Text := format('%d', [B4]);
 edit8.Text := sHeatexType;
 edit9.Text := format('%f', [HeatexIn[0]]);
 edit10.Text := format('%f', [HeatexOut[0]]);

 GET_CALCULATION(B1, B2, HeatexIn[0], sHeatexType, B3, B4, HeatexOut[0]);

 edit11.Text := format('%d', [B1]);
 edit12.Text := format('%d', [B2]);
 edit13.Text := format('%d', [B3]);
 edit14.Text := format('%d', [B4]);
 edit15.Text := sHeatexType;
 edit16.Text := format('%f', [HeatexIn[0]]);
 edit17.Text := format('%f', [HeatexOut[0]]);

end;

[Chris Holbrook]

@Paul, where is the DLL please? I did not find it.

[Paul D. Elliott]

Chris,

It gets complicated.

I made my own DLL based on what was posted.
I didn't post the whole Delphi program.
If you use the code below you will need to modify the first line of the
Delphi code above to reflect where you put the DLL.
The Delphi code & this DLL are just using test data ( probably not what
the real program would use ).

#Compile DLL

Function TestIntDiv Alias "TestIntDiv" (ByVal a As Long, ByVal b As Long) Export As Single

  MsgBox "PowerBasic DLL Message: Input values are " + Str$(a)+" and " +Str$(b)
  Function=a/b

End Function

Sub GET_CALCULATION(ByRef B1 As Byte, ByRef B2 As Byte, ByRef HeatexIn As Double, ByRef sHeaterType As AsciiZ, ByRef B3 As Byte, ByRef B4 As Byte, ByRef HeatexOut As Double) Export
 Dim HeatexInArray(20) As Double
 Dim HeatexOutArray(50) As Double
 Dim i As Long
 Dim j As Long
 Dim VvxDataIn As Double Pointer
 Dim VvxDataOut As Double Pointer ' removed the 3 from the name

 'more code

 VvxDataIn=VarPtr(HeatexIn)
 For i=0 To 20
 HeatexInArray(i)=@VvxDataIn[i]
 Next i

 For i = 1 To 20
    HeatexInArray(0) += HeatexInArray(i)
 Next

 For j = 0 To 50
    HeatexOutArray(j) = HeatexInArray(0) * j
 Next
 'much more code

 ' sorry forgot to move the whole array back
 VvxDataOut = VarPtr(HeatexOut)
 For j = 0 To 50
    @VvxDataOut[j] = HeatexOutArray(j)
 Next

   B1 = Asc("a")
   B2 = Asc("b")
   'HeatexIN = 1.00
   MsgBox "in pb dll " & sHeaterType
   sHeaterType = "abcdef"
   B3 = Asc("x")
   B4 = Asc("y")
   'HeatexOut = 2.00
End Sub

[Paul D. Elliott]

Fredrik,

Did that answer your question?

I don't have a version of Delphi later than v7.


Chris,

Sorry. I forgot to move the whole output array out.
My program was only looking at 1st entry.