DeviceIoControl in BV.NET

[Tor Henrik Hovi]

:confused:

 

I'm trying to convert a VB6 example to VB.NET.

The example uses the DeviceIoControl function:

 

DeviceIoControl(hWD, IOCTL_WD_USB_SCAN_DEVICES, lpScan, LenB(lpScan), 0, 0, WinDriverGlobalDW, 0)

 

lpscan is a pointer to the Scan object.

 

My problem is i do not know how to make a pointer to a object.

 

Is it possible in VB.NET?

 

something like lpScan = pointer(Scan) ?????

[Derek Stone]

It all depends on what the "Scan" object is. The Marshal class under System.Runtime.InteropServices should provide you with a method to do just what you need.

 

Also, you should be using the Marshal.SizeOf method instead of VB.NET's LenB function.

[Tor Henrik Hovi]

Thank you for taking the time to answer my post.

Your suggestion of using the Marshall Class is definately a step in the right direction.:)

My proggie now compiles but gives me an error message:

"Type WD_USB_SCAN_DEVICES can not be marshaled as an unmanaged structure; no meaningful size or offset can be computed."

:confused: To explain the Scan Object/Structure I have extracted a bit of my code:

 

Structure WD_USB_ID
 Dim dwVendorId As Integer
 Dim dwProductId As Integer
End Structure

Structure WD_USB_HUB_GENERAL_INFO
 Dim fBusPowered As Integer
 Dim dwPorts As Integer
 Dim dwCharacteristics As Integer
 Dim dwPowerOnToPowerGood As Integer
 Dim dwHubControlCurrent As Integer
End Structure

Structure WD_USB_DEVICE_GENERAL_INFO
 Dim deviceId As WD_USB_ID
 Dim dwHubNum As Integer
 Dim dwPortNum As Integer
 Dim fHub As Integer
 Dim fFullSpeed As Integer
 Dim dwConfigurationsNum As Integer
 Dim deviceAddress As Integer
 Dim hubInfo As WD_USB_HUB_GENERAL_INFO
 Dim deviceClass As Integer
 Dim deviceSubClass As Integer
 Dim dwInterfaceNum As Integer
End Structure

Structure WD_USB_SCAN_DEVICES
 Dim searchId As WD_USB_ID
 Dim dwDevices As Integer
 <VBFixedArray(29)> Dim uniqueId() As Integer
  <VBFixedArray(29)> Dim deviceGeneralInfo() As WD_USB_DEVICE_GENERAL_INFO
  Dim dwStatus As Integer
 'UPGRADE_TODO: "Initialize" must be called to initialize instances of this structure. 
 Public Sub Initialize()
    ReDim uniqueId(29)
    ReDim deviceGeneralInfo(29)
 End Sub
End Structure

Function WD_UsbScanDevice(ByRef hWD As Integer) As WD_USB_SCAN_DEVICES
 Dim Scan As WD_USB_SCAN_DEVICES
 Scan.Initialize()
 Dim memSize As Integer = System.Runtime.InteropServices.Marshal.SizeOf(Scan)
 Dim lpScan As IntPtr = System.Runtime.InteropServices.Marshal.AllocHGlobal(memSize)
 Dim lpScan2 As Integer = lpScan.ToInt64()
 DeviceIoControl(hWD, IOCTL_WD_USB_SCAN_DEVICES, lpScan2, memSize, 0, 0, WinDriverGlobalDW, 0)
 Return Scan
End Function

Edited March 6, 2003 by divil

[Derek Stone]

Try replacing the WD_USB_SCAN_DEVICES with the following declaration instead.

Structure WD_USB_SCAN_DEVICES
   Dim searchId As WD_USB_ID
   Dim dwDevices As Integer
   MarshalAs(UnmanagedType.LPArray, SizeConst:=29)>Dim uniqueId() As Integer
   MarshalAs(UnmanagedType.LPArray, SizeConst:=29)>Dim deviceGeneralInfo() As WD_USB_DEVICE_GENERAL_INFO
   Dim dwStatus As Integer
End Structure

As it stands now the SizeOf method is getting passed arrays of unfixed sizes, meaning it can't calculate the entire size of the structure.

[Tor Henrik Hovi]

Your declaration did not compile without the "<" so i Included those but unfortunately I still got the same ERROR message when trying the Marshal.SizeOf():

"Type WD_USB_SCAN_DEVICES can not be marshaled as an unmanaged structure; no meaningful size or offset can be computed."

 

Structure WD_USB_SCAN_DEVICES
       Dim searchId As WD_USB_ID
       Dim dwDevices As Integer
       <MarshalAs(UnmanagedType.LPArray, SizeConst:=29)> Dim uniqueId() As Integer
       <MarshalAs(UnmanagedType.LPArray, SizeConst:=29)> Dim deviceGeneralInfo() As WD_USB_DEVICE_GENERAL_INFO
       Dim dwStatus As Integer
   End Structure


  Function WD_UsbScanDevice(ByRef hWD As Integer) As WD_USB_SCAN_DEVICES
       Dim Scan As WD_USB_SCAN_DEVICES
       Dim memSize As Integer = Marshal.SizeOf(Scan)
       Dim lpScan As IntPtr = Marshal.AllocHGlobal(memSize)
       Dim lpScan2 As Integer = lpScan.ToInt64()
       DeviceIoControl(hWD, IOCTL_WD_USB_SCAN_DEVICES, lpScan2, memSize, 0, 0, WinDriverGlobalDW, 0)
       Return Scan
   End Function

 

While searching for clues on the net I stumbeled over this article that I belive to be written by you:

http://www.elitevb.com/content/print.aspx?contentid=75

This article mentiones an update about the very core of my problem.

If you have written this update, would you give me an URL to where it is?

Do you have any other ideas of what I'm doing wrong?

Edited March 11, 2003 by divil

[mogwai]

Tor,

 

Have you managed to find a solution to this problem yet ? I have also come across this issue with Marshalling, and I'm starting to tear my hair out over it... !

 

I'm having difficulty passing in a structure to DeviceIOControl which contains arrays of other structures, which in turn contain array of other structures.....

 

My problem is a bit earlier on that yours, in that I have followed Derek's above advice. Unfortunately I am getting an error when attempting to get the size of the structure through Marshal.SizeOf(), and it is saying Type "TOC can not be marshaled as an unmanaged structure; no meaningful size or offset can be computed."

 

Does anyone have any ideas what may be going wrong? If required I can post the relevant code here... ?

 

Cheers!

 

mogwai

[divil]

Try applying a LayoutKind attribute, with Sequential, on the structures.

[mogwai]

Try applying a LayoutKind attribute, with Sequential, on the structures.

I have tried this, but this is not the root of the cause. The structures I am using are all complex types, containing arrays of other structures etc, etc. I have tried setting the <FieldOffset> attribute of each structure member, but still no joy. I have a few ideas up my sleeve which I need to try later today, but I'm not confident they'll work...