Pass array to Dll?

[Todd Wasson]

Hello,

How could a Delphi EXE pass an array to a PB DLL? I'll need to have a couple of large two dimensional arrays and a bitmap stored in the DLL, but defined and sent by the Delphi program. The only way I know of is to use something like this:

  Set_Array_Size 500,500    (500 by 500 array)
  For X_Index = 1 to 500
   For Y_Index = 1 to 500
    Value = Array(X_Index,Y_Index)
    Set_Array_Value X,Y,Value
   Next
  Next

Is there a way to pass/copy an array to the PB DLL in one operation, rather thandoing this one element at a time, with thousands of function calls?

Thanks,
Todd Wasson
Performance Simulations
Drag Racing and Top Speed
Prediction Software http://PerformanceSimulations.Com


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[This message has been edited by Todd Wasson (edited January 29, 2001).]

[Colin Schmidt]

Hello,

How about you pass a pointer to the array along with two values for the size of the array:

MyFunctionInDll(pointerToArray AS LONG PTR, arrayXSize AS LONG, arrayYSize AS LONG)

You will then need to look up how pointers work and how to use pointer off sets.

If you would like a small example email me at [email protected]

Hope that helps,
Colin Schmidt

------------------
Colin Schmidt & James Duffy, Praxis Enterprises, Canada

PS: Todd: I'm building a 76 Buick Skyhawk with a 3.8 Buick Turbo with about 350h

[This message has been edited by Colin Schmidt (edited January 29, 2001).]

[Todd Wasson]

Thanks, Colin.

I'd like to see your example. Building the Skyhawk, huh? About time! I wonder how close AqueTree will be Will email you.

Thanks again,

------------------
Todd Wasson
-------------
Performance Simulations
Drag Racing and Top Speed
Prediction Software
http://PerformanceSimulations.Com

[Lance Edmonds]

To recap Colin's reply, you can use the same strategy as passing an array from VB to PB.

Pass the 1st element of the array by reference (BYREF) to the DLL function (along with a couple of variables to tell the code how big the array bounds are).

Then in the DLL, receive the 1st parameter as a BYVAL DWORD, then use DIM..AT to declare a PB array over the top of the Delphi array.

From there, you can reference the array with normal PowerBASIC array code rather than dealing with pointers.

I'm not a Delphi programmer so I have no idea how to ensure that the 1st array element is passed BYREF - I'm sure you'll figure that one out!

However, the PB code would look something like this:

FUNCTION MyFunc(BYVAL arr AS DWORD, x AS LONG, y AS LONG) EXPORT AS LONG
  DIM PBarray(1:x,1:y) AS LONG AT arr
  PBarray(1,1) = 123456&
  ARRAY SORT PBarray(1) FOR x     ' 1st dimension sort
  ARRAY SORT PBarray(y + 1) FOR x ' 2nd dimension sort
  FUNCTION = -1 ' success!
END FUNCTION

I hope this helps!


------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Todd Wasson]

Thanks, Lance. We posted at exactly the same time, how often does that happen?
I'll need to try out the code and read more about these things in the help files, as this code looks Greek to me!

Thanks again,


------------------
Todd Wasson
-------------
Performance Simulations
Drag Racing and Top Speed
Prediction Software
http://PerformanceSimulations.Com

[Todd Wasson]

Please, if you can, refrain from laughing at the attempt below! The PBMAIN function here simulates the Delphi EXE by creating an array (DelphArray). Then, it calls the simulated DLL function to store it as Pbarray. Obviously, I'm doing this wrong, but do you see what I'm trying to do?

#COMPILE EXE
DEFSNG A-Z
'
FUNCTION MyFunc(BYVAL arr AS DWORD,x AS LONG,y AS LONG) AS LONG
LOCAL TEXT AS STRING
  DIM PBarray(1:x,1:y) AS LONG AT arr
  PBarray(1,1) = 123456&
  ARRAY SORT PBarray(1) FOR x     ' 1st dimension sort
  ARRAY SORT PBarray(y + 1) FOR x ' 2nd dimension sort
  FUNCTION = -1 ' success!
END FUNCTION
'
FUNCTION PBMAIN()
'Delphi EXE makes an array to pass to DLL function
DIM DelphArray(1:10,1:10) AS LONG
FOR x = 1 TO 10
    FOR y = 1 TO 10
        DelphArray(x,y) = x + y
    NEXT
NEXT
'Now, the simulated Delphi EXE calls my DLL function, storing data
'in PBarray (the DLL storage array).  This is obviously not the right way   [img]http://www.powerbasic.com/support/forums/smile.gif[/img]
MyFunc DelphArray,10,10
END FUNCTION

Am I way off here? Must be!

Thanks,

------------------
Todd Wasson
-------------
Performance Simulations
Drag Racing and Top Speed
Prediction Software http://PerformanceSimulations.Com



[This message has been edited by Todd Wasson (edited January 29, 2001).]

[Lance Edmonds]

Heh! The problem with trying this technique all in one module is that the target function declaration is known to PB, so the compiler is expecting you to pass the 1st element BYVAL. When we are using this in a DLL format, we get the result that we want since there is no parameter checking other than a suitable declaration in the Delphi code.

So, in order to make this work within one PB module, you'll have to override the typechecking on the calling code, thus:

MyFunc BYVAL VARPTR(DelphArray(1,1)), 10, 10 
' The (1,1) is needed so we pass the address of the 1st element, not the address of the array descriptor.

------------------
Lance
PowerBASIC Support
mailto:[email protected][email protected]</A>

[Colin Schmidt]

Well, you have it already! I'm assuming you don't need the example. If so however just email me. However, it will be late tomorrow afternoon before I get to it.

Colin

------------------
Colin Schmidt & James Duffy, Praxis Enterprises, Canada
[email protected]

[Todd Wasson]

Thanks, guys Here's a little benchmark comparison between your method and the one I was considering. Quite an improvement in speed this way!

#COMPILE EXE
DEFSNG A-Z
GLOBAL PBarray2() AS LONG

FUNCTION InputLoopMethod(BYVAL x AS LONG,BYVAL  y AS LONG, BYVAL value AS LONG) AS LONG
PBarray2(x,y) = value
END FUNCTION

FUNCTION MyFunc(BYVAL arr AS DWORD,x AS LONG,y AS LONG) AS LONG
LOCAL TEXT AS STRING
  DIM PBarray(1:x,1:y) AS LONG AT arr
  ARRAY SORT PBarray(1) FOR x     ' 1st dimension sort
  ARRAY SORT PBarray(y + 1) FOR x ' 2nd dimension sort
  FUNCTION = -1 ' success!
'For small 10x10 or so sized arrays, view the list here
'  FOR x_index = 1 TO x
'      FOR y_index = 1 TO y
'  TEXT$ = TEXT$ + FORMAT$(PBarray(x_index,y_index),"##  ")
'      NEXT
'  NEXT
'  MSGBOX TEXT$
END FUNCTION

FUNCTION PBMAIN()
'Delphi EXE makes an array to pass to DLL function
DIM Num_X_Elements AS LONG
DIM Num_Y_Elements AS LONG
Num_X_Elements = 10000
Num_Y_Elements = 100
DIM DelphArray(1:Num_X_Elements,1:Num_Y_Elements) AS LONG
FOR x = 1 TO Num_X_Elements
    FOR y = 1 TO Num_Y_Elements
        DelphArray(x,y) = x + y
    NEXT
NEXT
MSGBOX "Array initialization complete.  Press 'ok' to continue.",,"Ready"
'Now, the Delphi EXE calls my DLL function, storing data
'in PBarray.
''This is used only if "MyFunc" is in a DLL
'MyFunc DelphArray,10,10
''Otherwise, use this:
t0 = TIMER
MyFunc BYVAL VARPTR(DelphArray(1,1)), Num_X_Elements, Num_Y_Elements
t1 = TIMER
ElapsedTime1 = t1 - t0
TEXT$ = STR$(ElapsedTime1)
MSGBOX "Method 1 elapsed time: " + TEXT$,,"Test 1 of 2"


'''Try input loop method:
DIM Value AS LONG
DIM PBarray2(1:x,1:y) AS LONG
t0 = TIMER
FOR x = 1 TO Num_X_Elements
    FOR y = 1 TO Num_Y_Elements
        value = DelphArray(x,y)
        InputLoopMethod x,y,value
    NEXT
NEXT
t1 = TIMER
ElapsedTime2 = t1 - t0
TEXT$ = STR$(ElapsedTime2)
MSGBOX "Method 2 elapsed time: " + TEXT$,,"Test 2 of 2"
IF ElapsedTime1 <> 0 THEN
  MSGBOX "Method 1 was " + STR$(ElapsedTime2 / ElapsedTime1) + " times faster in this test:0)   Thanks to Lance and Colin!",,"Hooray!"
END IF
END FUNCTION

------------------
Todd Wasson
-------------
Performance Simulations
Drag Racing and Top Speed
Prediction Software http://PerformanceSimulations.Com

[This message has been edited by Todd Wasson (edited January 31, 2001).]