DLL Callback

[Nigel Walton]

I am trying to read some data from a dll via a callback. I have a
deligate and all imformation is correct except for an array.

This is the original struct in c:

typedef void (*PutSampProc)( short samples[], int arraylen, int
nrsamples,void *userData);

This does not work:

<StructLayout(L ayoutKind.Seque ntial)_
Public Structure PutSampProc2
<MarshalAs(Unma nagedType.ByVal Array,SizeConst :=1024)_
Dim Samples() As Short
Dim ArrayLen As Integer
Dim NrSamples As Integer
Dim Userdata As Byte
End Structure

This gives the correct data for ArrayLen, NrSamples and Userdata, but
just a value for the Samples():

<StructLayout(L ayoutKind.Seque ntial)_
Public Structure PutSampProc
Dim Samples As Integer
Dim ArrayLen As Integer
Dim NrSamples As Integer
Dim Userdata As Byte
End Structure

What am I doing wrong????

Please help

Nigel


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[Mattias Sjögren]

Re: DLL Callback

Nigel,

>This is the original struct in c:
>
>typedef void (*PutSampProc)( short samples[], int arraylen, int
>nrsamples,vo id *userData);

This is not a struct declaration, it's a function pointer type.


Mattias

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Mattias Sjögren [C# MVP] mattias @ mvps.org
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[Nigel Devon]

Re: DLL Callback

I now have it working like this:

Private Sub SampProc(ByVal Samples As Integer, ByVal ArrayLen As
Integer, ByVal NrSamples As Integer, ByVal UserData As Byte)
ReDim MySamples((NrSa mples * 2) - 1)
Marshal.Copy(Sa mples, MySamples, 0, NrSamples * 2)

Is it possible to receive 'Samples' as an array. Do I have to add some
marshalling code to my delegate?

Nigel

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