Moving array data with a DLL. [Help]

BlitzMax Forums/BlitzMax Programming/Moving array data with a DLL. [Help]

GW	(Posted 2009) [#1]

I have a DLL written in Bmax (with Sweenie's MakeDLL tool).
I want to transfer a pointer to an array from the host to the dll and have the dll populate the array. I've tried this a dozen different ways and each one just crashes Bmax.
Here is the Dll function.

'// Maparray[,] is declared global in the dll and populated
 
Function GetMapTest:Int(map:Int Ptr) "win32"	'EXPORT
	GCEnter()
	Local p:Int Ptr
	p = map
	Local X:Int, Y:Int, I:Int
	For X = 0 To MAPW - 1
		For Y = 0 To MAPH - 1
			p[(X * MAPW) + Y] = MapArray[x, y]
		Next
	Next
	Return True
End Function

Here is how the host in bmax is calling the function.

Global Maparray:Int[(MAPH * MAPW)]

Local tmp:=Int Ptr

tmp = Varptr Maparray[0]

GetMapTest(tmp)   <-- CRASH!!

I know that I could just pass Bmax arrays around directly, but i want this dll usable by other languages.

How is it possible to get array data from a dll.
Can anyone clue me in?

Thanks

Ked	(Posted 2009) [#2]

Why are you only passing the first index?

tmp = Varptr Maparray[0]

You are going beyond map's limits in:

For X = 0 To MAPW - 1
	For Y = 0 To MAPH - 1
		p[(X * MAPW) + Y] = MapArray[x, y]
	Next
Next

GW	(Posted 2009) [#3]

Its not the first index, its a pointer to the beginning of the array.

grable

(Posted 2009) [#4]

Its not the first index, its a pointer to the beginning of the array.

You dont need to specifically do that anymore, a straight

Local p:Int Ptr = array

should suffice ;)

It could be (X*MAPW)+Y is not correct, if the width is not same as height you wont get the result you expect.
im guessing what you want is X+(Y*MAPW)?

GW	(Posted 2009) [#5]

You dont need to specifically do that anymore, a straight
Local p:Int Ptr = array
should suffice ;)

hmm.. When did that change? that does work. Thanks

Your right about the map dimensions too that are being calculated. that was causing some additional explosions.
Thanks!