Hi,

I'm trying to use a custom dll written in C in my VB
program. The C library uses many structs but none are
very complicated. I cannot use MarshalAs to Marshal the
data.

I'm wondering if anyone has experience with this and can
provide me with a couple of examples.

Thanks,

tdcrotty

One way is to convert your parameters which are structure type into bytes
arrays.
You have to make a 2 functions :
- one to transform your struct into an array of bytes in order to be
sent to your DLL's functions
- one to transform bytes arrays that you'll receive from your DLL into
your managed structure

Thomas.

"tdcrotty" <(E-Mail Removed)> a écrit dans le message de
news:0d8501c3a3ae$2bc5dbd0$(E-Mail Removed)...
> Hi,
>
> I'm trying to use a custom dll written in C in my VB
> program. The C library uses many structs but none are
> very complicated. I cannot use MarshalAs to Marshal the
> data.
>
> I'm wondering if anyone has experience with this and can
> provide me with a couple of examples.
>
> Thanks,
>
> tdcrotty

There are examples of this all over the OpenNetCF library. I'm not sure if
the site is back up or not, but it's www.opennetcf.org. There are lots of
p/invoke examples in the archives of this newsgroup, also:

http://groups.google.com/groups?hl=e...mpactframework

Paul T.

"Thomas" <(E-Mail Removed)> wrote in message
news:uQCWl%(E-Mail Removed)...
> One way is to convert your parameters which are structure type into bytes
> arrays.
> You have to make a 2 functions :
> - one to transform your struct into an array of bytes in order to be
> sent to your DLL's functions
> - one to transform bytes arrays that you'll receive from your DLL into
> your managed structure
>
> Thomas.
>
> "tdcrotty" <(E-Mail Removed)> a écrit dans le message de
> news:0d8501c3a3ae$2bc5dbd0$(E-Mail Removed)...
> > Hi,
> >
> > I'm trying to use a custom dll written in C in my VB
> > program. The C library uses many structs but none are
> > very complicated. I cannot use MarshalAs to Marshal the
> > data.
> >
> > I'm wondering if anyone has experience with this and can
> > provide me with a couple of examples.
> >
> > Thanks,
> >
> > tdcrotty
>
>

Thanks for the link. I'll check it out.

td
>-----Original Message-----
>There are examples of this all over the OpenNetCF
library. I'm not sure if
>the site is back up or not, but it's www.opennetcf.org.
There are lots of
>p/invoke examples in the archives of this newsgroup,
also:
>
>http://groups.google.com/groups?hl=e...ang_en&ie=UTF-
8&oe=UTF-
8&group=microsoft.public.dotnet.framework.compactframework
>
>Paul T.
>
>"Thomas" <(E-Mail Removed)> wrote in message
>news:uQCWl%(E-Mail Removed)...
>> One way is to convert your parameters which are
structure type into bytes
>> arrays.
>> You have to make a 2 functions :
>> - one to transform your struct into an array of
bytes in order to be
>> sent to your DLL's functions
>> - one to transform bytes arrays that you'll
receive from your DLL into
>> your managed structure
>>
>> Thomas.
>>
>> "tdcrotty" <(E-Mail Removed)> a écrit dans le message
de
>> news:0d8501c3a3ae$2bc5dbd0$(E-Mail Removed)...
>> > Hi,
>> >
>> > I'm trying to use a custom dll written in C in my VB
>> > program. The C library uses many structs but none
are
>> > very complicated. I cannot use MarshalAs to Marshal
the
>> > data.
>> >
>> > I'm wondering if anyone has experience with this and
can
>> > provide me with a couple of examples.
>> >
>> > Thanks,
>> >
>> > tdcrotty
>>
>>
>
>
>.
>

Thanks,

SO is this a form of manually marshalling? Just send the
data as raw bytes and return raw bytes from the dll
functions?

td
>-----Original Message-----
>One way is to convert your parameters which are
structure type into bytes
>arrays.
>You have to make a 2 functions :
> - one to transform your struct into an array of
bytes in order to be
>sent to your DLL's functions
> - one to transform bytes arrays that you'll receive
from your DLL into
>your managed structure
>
>Thomas.
>
>"tdcrotty" <(E-Mail Removed)> a écrit dans le message de
>news:0d8501c3a3ae$2bc5dbd0$(E-Mail Removed)...
>> Hi,
>>
>> I'm trying to use a custom dll written in C in my VB
>> program. The C library uses many structs but none are
>> very complicated. I cannot use MarshalAs to Marshal
the
>> data.
>>
>> I'm wondering if anyone has experience with this and
can
>> provide me with a couple of examples.
>>
>> Thanks,
>>
>> tdcrotty
>
>
>.
>

Maybe we can say that.
You must take care of the type of the data you have in your structures
(about the length in bytes of each variable).

A sample of a Getbytes/Decode functions (sorry but the comments are in
French) :

'--------------------------------------------------------

'Transforme une instance de ActionKey en tableau de bytes

'

'Valeur retournée :

' TRUE si OK, FALSE sinon

'--------------------------------------------------------

Private Function GetBytes(ByRef TabBytes() As Byte) As Boolean

Dim i As Integer

Dim max As Integer

Dim max2 As Integer

Try

'On redimensionne le tableau

ReDim TabBytes(1324)

'Entier IDBouton = 4 bytes

BitConverter.GetBytes(IDBouton).CopyTo(TabBytes, 0)

'Entier TypeClick = 4 bytes

BitConverter.GetBytes(TypeClick).CopyTo(TabBytes, 4)

'Entier Typeaction = 4 bytes

BitConverter.GetBytes(TypeAction).CopyTo(TabBytes, 8)

'Booléen Son = 4 bytes

BitConverter.GetBytes(Son).CopyTo(TabBytes, 12)

'Tableau de bytes Keyboard = 260 * 1 byte

If Not IsNothing(Keyboard) Then

max = Keyboard.GetUpperBound(0)

For i = 0 To max

TabBytes(i + 16) = Keyboard(i)

Next

End If

'Entier TailleKeyboard = 4 bytes

BitConverter.GetBytes(TailleKeyboard).CopyTo(TabBytes, 276)

'Entier DureeClick = 4 bytes

BitConverter.GetBytes(DureeClick).CopyTo(TabBytes, 280)

'Tableau de caractères Application = 260 * 2 bytes

If Not IsNothing(Application) Then

max = Application.GetUpperBound(0)

For i = 0 To max

BitConverter.GetBytes(Application(i)).CopyTo(TabBytes, 284 + (2 * i))

Next

End If

'Tableau de caractères Paramètres = 260 * 2 bytes

If Not IsNothing(Parametres) Then

max = Parametres.GetUpperBound(0)

For i = 0 To max

BitConverter.GetBytes(Parametres(i)).CopyTo(TabBytes, 804 + (2 * i))

Next

End If

GetBytes = True

Catch ex As Exception

GetBytes = False

End Try



End Function



'---------------------------------------------------------------------------
----------

'Analyse le tableau de bytes retourné par lecture des infos d'un bouton du
Gotive

'et inscrit ces données dans les membres de la classe

'

'Valeur retournée :

' TRUE si OK, FALSE sinon

'---------------------------------------------------------------------------
----------

Private Function Decode(ByVal TabBytes() As Byte) As Boolean

Dim i As Integer

Try

'Entier IDBouton = 4 bytes

IDBouton = BitConverter.ToUInt32(TabBytes, 0)

'Entier TypeClick = 4 bytes

TypeClick = BitConverter.ToUInt32(TabBytes, 4)

'Entier Typeaction = 4 bytes

TypeAction = BitConverter.ToUInt32(TabBytes, 8)

'Booléen Son = 4 bytes

Son = BitConverter.ToBoolean(TabBytes, 12)

'Tableau de bytes Keyboard = 260 * 1 byte

For i = 0 To 259

Keyboard(i) = TabBytes(i + 16)

Next

'Entier TailleKeyboard = 4 bytes

TailleKeyboard = BitConverter.ToUInt32(TabBytes, 276)

'Entier DureeClick = 4 bytes

DureeClick = BitConverter.ToUInt32(TabBytes, 280)

'Tableau de caractères Application = 260 * 2 bytes

For i = 0 To 259

Application(i) = BitConverter.ToChar(TabBytes, 284 + (2 * i))

Next

'Tableau de caractères Paramètres = 260 * 2 bytes

For i = 0 To 259

Parametres(i) = BitConverter.ToChar(TabBytes, 804 + (2 * i))

Next

Decode = True

Catch ex As Exception

Decode = False

End Try

End Function


Thomas.

"tdcrotty" <(E-Mail Removed)> a écrit dans le message de
news:08a201c3a423$75e55400$(E-Mail Removed)...
Thanks,

SO is this a form of manually marshalling? Just send the
data as raw bytes and return raw bytes from the dll
functions?

td
>-----Original Message-----
>One way is to convert your parameters which are
structure type into bytes
>arrays.
>You have to make a 2 functions :
> - one to transform your struct into an array of
bytes in order to be
>sent to your DLL's functions
> - one to transform bytes arrays that you'll receive
from your DLL into
>your managed structure
>
>Thomas.
>
>"tdcrotty" <(E-Mail Removed)> a écrit dans le message de
>news:0d8501c3a3ae$2bc5dbd0$(E-Mail Removed)...
>> Hi,
>>
>> I'm trying to use a custom dll written in C in my VB
>> program. The C library uses many structs but none are
>> very complicated. I cannot use MarshalAs to Marshal
the
>> data.
>>
>> I'm wondering if anyone has experience with this and
can
>> provide me with a couple of examples.
>>
>> Thanks,
>>
>> tdcrotty
>
>
>.
>

Have you looked at the FAQ? There are several links in the following entry
to articles.

6.1. How do I call a function that is in a native DLL?
http://msdn.microsoft.com/mobility/p...fault.aspx#6.1

--
Geoff Schwab
Program Manager
Excell Data Corporation
http://msdn.com/mobility
http://msdn.microsoft.com/mobility/p...Q/default.aspx

This posting is provided "AS IS" with no warranties, and confers no rights.
"tdcrotty" <(E-Mail Removed)> wrote in message
news:0d8501c3a3ae$2bc5dbd0$(E-Mail Removed)...
> Hi,
>
> I'm trying to use a custom dll written in C in my VB
> program. The C library uses many structs but none are
> very complicated. I cannot use MarshalAs to Marshal the
> data.
>
> I'm wondering if anyone has experience with this and can
> provide me with a couple of examples.
>
> Thanks,
>
> tdcrotty