Conversion from VC++ to VB.NET

[Susheelss]

Hi,
Can anybody please help me to convert this code (Structure and its members) which is in VC++ to VB.NET.

#define GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH 16
#define GBIF_STRING_DATATYPE unsigned char

typedef struct
{	
	GBIF_STRING_DATATYPE	ucMacAddress[GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH];			// unsigned since the adress components can be higher than 128
	GBIF_STRING_DATATYPE	ucIP[GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH];
	GBIF_STRING_DATATYPE	ucSubnetMask[GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH];
	GBIF_STRING_DATATYPE	ucGateway[GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH];
	GBIF_STRING_DATATYPE	ucAdapterIP[GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH];
	GBIF_STRING_DATATYPE	ucAdapterMask[GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH];

	DWORD					dwIPCurrentBootOptions;
	CHAR 					cManufacturerName[32];										// PerkinElmer
	CHAR					cModelName[32];												// GBIF
	CHAR					cGBIFFirmwareVersion[32];
	CHAR					cDeviceName[16];

} GBIF_DEVICE_PARAM;

Regards,
Susheelss

[jmcilhinney]

Is this for the purpose of calling an unmanaged function?

[Susheelss]

Thanks Mr.jmcilhinney for ur reply.

YES.

I want to send a pointer to this structure as a parameter to a DLL call so that the call returns the values of this structure filled.

[Susheelss]

I'm not getting how to define the "GBIF_STRING_DATATYPE" as an unsigned char array. Should I have it as Character array or as a String Builder.

[Niya]

Try this:-

'
    Public Const GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH = 16
 
    Public Structure GBIF_DEVICE_PARAM
 
        <MarshalAs(UnmanagedType.LPStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucMacAddress As String
 
        <MarshalAs(UnmanagedType.LPStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucIP As String
 
        <MarshalAs(UnmanagedType.LPStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucSubnetMask As String
 
        <MarshalAs(UnmanagedType.LPStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucGateway As String
 
        <MarshalAs(UnmanagedType.LPStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucAdapterIP As String
 
        <MarshalAs(UnmanagedType.LPStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucAdapterMask As String
 
        Public dwIPCurrentBootOptions As Integer
 
        <MarshalAs(UnmanagedType.LPStr, sizeconst:=32)> _
        Public cManufacturerName As String
 
        <MarshalAs(UnmanagedType.LPStr, sizeconst:=32)> _
        Public cModelName As String
 
        <MarshalAs(UnmanagedType.LPStr, sizeconst:=32)> _
        Public cGBIFFirmwareVersion As String
 
        <MarshalAs(UnmanagedType.LPStr, sizeconst:=16)> _
        Public cDeviceName As String
 
    End Structure

[ident]

courtesy of c++ to vb

#Const GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH = True
'C++ TO VB CONVERTER NOTE: The following #define macro was replaced in-line:
'ORIGINAL LINE: #define GBIF_STRING_DATATYPE unsigned char
#Const GBIF_STRING_DATATYPE = True
 
Public Class GB
    Public ucMacAddress(DefineConstants.GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH - 1) As Byte ' unsigned since the adress components can be higher than 128
    Public ucIP(DefineConstants.GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH - 1) As Byte
    Public ucSubnetMask(DefineConstants.GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH - 1) As Byte
    Public ucGateway(DefineConstants.GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH - 1) As Byte
    Public ucAdapterIP(DefineConstants.GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH - 1) As Byte
    Public ucAdapterMask(DefineConstants.GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH - 1) As Byte
 
    Public dwIPCurrentBootOptions As UInteger
    Public cManufacturerName As New String(New Char(31){}) ' PerkinElmer
    Public cModelName As New String(New Char(31){}) ' GBIF
    Public cGBIFFirmwareVersion As New String(New Char(31){})
    Public cDeviceName As New String(New Char(15){})
 
End Class
 
Friend NotInheritable Class DefineConstants
    Public Const GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH As Integer = 16
End Class

[Niya]

That would work too. However this:-

#define GBIF_STRING_DATATYPE unsigned char

Would imply that those members are meant to be treated as strings and not binary data.

[Susheelss]

Thanks Mr.ident and Mr.Niya for your valuable reply.

Mr.Niya now I tried sending the Pointer to this structure(which you posted) in a DLL function call as given below:

Dim SensorNumDetected As Integer = 1

        Dim pGbIF_DEVICE_PARAM As GBIF_DEVICE_PARAM

        Dim myptr As IntPtr = Marshal.AllocHGlobal(Marshal.SizeOf(pGbIF_DEVICE_PARAM))

        Marshal.StructureToPtr(pGbIF_DEVICE_PARAM, myptr, False)

        DllCallReturnValue = Acquisition_GbIF_GetDeviceList(Marshal.PtrToStructure(myptr, pGbIF_DEVICE_PARAM.GetType()), SensorNumDetected)

The function call signature is as given below:

 <DllImport("Detector.dll")> Public Function Acquisition_GbIF_GetDeviceList(ByRef p_GBIF_DEVICE_PARAM As GBIF_DEVICE_PARAM, ByVal nDeviceCnt As Integer) As Integer

    End Function

Now when i call this DLL function the function should fill the structure members values and return zero if success.But instead it is showing error which says :
"The runtime has encountered a fatal error. The address of the error was at 0x6dd8aa31, on thread 0xf34. The error code is 0xc0000005. This error may be a bug in the CLR or in the unsafe or non-verifiable portions of user code. Common sources of this bug include user marshaling errors for COM-interop or PInvoke, which may corrupt the stack."

Can you please tell what is the change I should be doing.

Regards,
Susheelss.

[Niya]

It seems that function is meant to fill out an array of that structure so you should try declaring that API to take an array of the GBIF_DEVICE_PARAM type.

[Susheelss]

The C++ DLL function is given like this:

'Function Signature
Acquisition_GbIF_GetDeviceList(GBIF_DEVICE_PARAM* pGBIF_DEVICE_PARAM, int nDeviceCnt);

'Actual function call
	GBIF_DEVICE_PARAM* pGbIF_DEVICE_PARAM = (GBIF_DEVICE_PARAM*)malloc( sizeof(GBIF_DEVICE_PARAM)*(ulNumSensors));
			
			iRet = Acquisition_GbIF_GetDeviceList(pGbIF_DEVICE_PARAM,ulNumSensors);

Here in C++ code he is not sending array of structures as parameter to the function call.
Instead while allocating space in malloc statement, he is allocation the space
for the pointer to structure for total number of sensors detected.
In my case, since I have connected to only one detector, I just allocated space for one structure.
If this is wrong, then please tell me how should I allocate the space for multiple number of sensors connected.
Thanks and Regards,
Susheelss

[Niya]

I was slightly wrong about declaring the structure. Use this instead:-

'
    Public Const GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH = 16
 
    <StructLayout(LayoutKind.Sequential)> _
    Public Structure GBIF_DEVICE_PARAM
 
        <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucMacAddress As String
 
        <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucIP As String
 
        <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucSubnetMask As String
 
        <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucGateway As String
 
        <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucAdapterIP As String
 
        <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucAdapterMask As String
 
        Public dwIPCurrentBootOptions As Integer
 
        <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=32)> _
        Public cManufacturerName As String
 
        <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=32)> _
        Public cModelName As String
 
        <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=32)> _
        Public cGBIFFirmwareVersion As String
 
        <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=16)> _
        Public cDeviceName As String
 
    End Structure

And declare your API as:-

<DllImport("YourDll.Dll")> _
    Private Shared Function Acquisition_GbIF_GetDeviceLis(<Out()> ByVal dev() As GBIF_DEVICE_PARAM, ByVal devCount As Integer) As Integer
    End Function

Make sure that you resize your array based on devCount before passing it into the function. I don;t know the name of the DLL where that function resides so you will have to replace "YourDll.Dll" in my example above with whatever the DLL's name is.

[Niya]

Here in C++ code he is not sending array of structures as parameter to the function call.
Instead while allocating space in malloc statement, he is allocation the space
for the pointer to structure for total number of sensors detected.

In other words, an array

[Susheelss]

Thanks Mr.Niya for your valuable reply.

As you said I copy pasted the structure and the DLL call in my module.

But it gave the error saying "Methods in a cannot be declared 'shared'". Hence I removed the shared keyword and pasted the DLL call signature in the module.

Then I declared the array of structure based on the device count and the coding done was as follows:

Dim SensorsNum As Integer = 1
Dim DllCallReturnValue As Integer
Dim pGbIF_DEVICE_PARAM() As GBIF_DEVICE_PARAM

ReDim pGbIF_DEVICE_PARAM(SensorsNum)

Dim myptr As IntPtr = Marshal.AllocHGlobal(Marshal.SizeOf(pGbIF_DEVICE_PARAM(SensorsNum)))

Marshal.StructureToPtr(pGbIF_DEVICE_PARAM(SensorsNum), myptr, False)

DllCallReturnValue = Acquisition_GbIF_GetDeviceList(Marshal.PtrToStructure(myptr, pGbIF_DEVICE_PARAM(SensorsNum).GetType()), SensorsNum)

But now I'm getting an error saying
" 'Acquisition_GbIF_GetDeviceList' is not declared.It may be inaccessible due to its protection level."

I think the function signature is not matching with the actual function call, as
in the function call I'm sending Pointer to structure as 1st parameter and in signature I am having 1st parameter as array of structure. Structure send as a value(Byval).
Can you please tell me how to resolve this?

Thanks and Regards,
Susheelss.

[Susheelss]

Sorry it was my mistake> I did not see the function call declared as private. I changed it to Public. Now I think It should work. Will get back after testing.

[Susheelss]

Mr.Niya As per your directions I declared the function call as below:

<DllImport("MyDLL.dll")> Public Function Acquisition_GbIF_GetDeviceList(<Out()> ByVal pGbIF_DEVICE_PARAMS() As GBIF_DEVICE_PARAM, ByVal devCount As Integer) As Integer

End Function

   Dim pGbIF_DEVICE_PARAM() As GBIF_DEVICE_PARAM

        ReDim pGbIF_DEVICE_PARAM(SensorsNum)

        Dim myptr As IntPtr = Marshal.AllocHGlobal(Marshal.SizeOf(pGbIF_DEVICE_PARAM(SensorsNum)))

        Marshal.StructureToPtr(pGbIF_DEVICE_PARAM(SensorsNum), myptr, False)

        DllCallReturnValue = Acquisition_GbIF_GetDeviceList(Marshal.PtrToStructure(myptr, pGbIF_DEVICE_PARAM(ulNumSensors).GetType()), SensorsNum)

Now I'm getting Error saying:
"Unable to cast object of type 'GBIF_DEVICE_PARAM' to type 'GBIF_DEVICE_PARAM[]'."

[Susheelss]

Can anybody please suggest me how this Type Casting issue can be resolved and hence to get the Structure members filled through DLL all?

Thanks and Regards,
Susheelss

[Niya]

Pass the array as you would pass it to a .Net function. No need to obtain its pointer through the Marshal class. Also, please pay attention to what I said....I told you to replace this <DllImport("MyDLL.dll")>. The MyDll.dll should be the name of the dll file that has your function.

[Susheelss]

Thanks Mr.Niya. The problem is resolved. Thanks for your support. Hope it continues the same way. I was struggling on this function call from past 15 days. Finally it solved because of your help.

Regards,
Susheelss.

[Niya]

Do not forget to dimension the array before passing it into the unmanaged function. You would risk invalid memory writes if you don't.

[Susheelss]

Now that I was able to get all the structure parameters I am struck with another call which is as follows:

// "HANDLE" in below definition defined as Void pointer in "WinNT.h" file.
typedef void *HANDLE;
typedef HANDLE HACQDESC;

#define GBIF_STRING_DATATYPE unsigned char

HIS_RETURN Acquisition_GbIF_Init(HACQDESC *phAcqDesc,
					      int nChannelNr,
					      BOOL bEnableIRQ, 
					      UINT uiRows, UINT uiColumns, 
					      BOOL bSelfInit, BOOL bAlwaysOpen,
					      long lInitType, 
					      GBIF_STRING_DATATYPE* cAddress);

I am suppose to send the return value of "ucIP" structure member for "cAddress".

But in Vb.NET when I tried the code as below:

 Dim hAcqDesc As IntPtr
        Dim bEnableIRQ As Boolean = True
        Dim dwRows As UInt32 = 0
        Dim dwColumns As UInt32 = 0
        Dim bSelfInit As Boolean = True
        Dim SET_FALSE As Boolean = False
        Const HIS_GbIF_IP = 1
        Dim lOpenMode As Long = HIS_GbIF_IP
        Dim Detector_ucIP As String

  <DllImport("MYDLL.dll")> Public Function Acquisition_GbIF_Init(ByRef HACQDESC As IntPtr, ByVal nChannelNr As Integer, ByVal bEnableIRQ As Boolean, ByVal uiRows As UInt32, ByVal uiColumns As UInt32, ByVal bSelfInit As Boolean, ByVal bAlwaysOpen As Boolean, ByVal lInitType As Long, ByREF cAddress As String) As Integer

 DllCallReturnValue = Acquisition_GbIF_Init(hAcqDesc, 0, bEnableIRQ, dwRows, dwColumns, bSelfInit, SET_FALSE, lOpenMode, )

    End Function

I am getting an error saying "Unable to fimd the entry point in the DLL".

Can Anybody please help me?????

[Susheelss]

Now that I was able to get all the structure parameters I am struck with another call which is as follows:

// "HANDLE" in below definition defined as Void pointer in "WinNT.h" file.
typedef void *HANDLE;
typedef HANDLE HACQDESC;

#define GBIF_STRING_DATATYPE unsigned char

HIS_RETURN Acquisition_GbIF_Init(HACQDESC *phAcqDesc,
					      int nChannelNr,
					      BOOL bEnableIRQ, 
					      UINT uiRows, UINT uiColumns, 
					      BOOL bSelfInit, BOOL bAlwaysOpen,
					      long lInitType, 
					      GBIF_STRING_DATATYPE* cAddress);

I am suppose to send the return value of "ucIP" structure member for "cAddress".

But in Vb.NET when I tried the code as below:

 Dim hAcqDesc As IntPtr
        Dim bEnableIRQ As Boolean = True
        Dim dwRows As UInt32 = 0
        Dim dwColumns As UInt32 = 0
        Dim bSelfInit As Boolean = True
        Dim SET_FALSE As Boolean = False
        Const HIS_GbIF_IP = 1
        Dim lOpenMode As Long = HIS_GbIF_IP
        Dim Detector_ucIP As String

  <DllImport("MYDLL.dll")> Public Function Acquisition_GbIF_Init(ByRef HACQDESC As IntPtr, ByVal nChannelNr As Integer, ByVal bEnableIRQ As Boolean, ByVal uiRows As UInt32, ByVal uiColumns As UInt32, ByVal bSelfInit As Boolean, ByVal bAlwaysOpen As Boolean, ByVal lInitType As Long, ByREF cAddress As String) As Integer

 DllCallReturnValue = Acquisition_GbIF_Init(hAcqDesc, 0, bEnableIRQ, dwRows, dwColumns, bSelfInit, SET_FALSE, lOpenMode, )

    End Function

I am getting an error saying "Unable to find the entry point in the DLL".

Can Anybody please help me?????

[Niya]

Is MYDLL.dll the actual name of your dll ? In any case, that error occurs when a function cannot be found in the dll. Maybe you spelt it wrong and I believe its also case sensitive.

[Susheelss]

Thanks Mr.Niya for your reply.
The DLL name name is not the problem as It is the same name.
The VC++ call is like this:

typedef HANDLE HACQDESC;
#define GBIF_STRING_DATATYPE unsigned char

HIS_RETURN Acquisition_GbIF_Init(HACQDESC *phAcqDesc,int nChannelNr,
BOOL bEnableIRQ, UINT uiRows, UINT uiColumns, BOOL bSelfInit,
BOOL bAlwaysOpen,long lInitType,GBIF_STRING_DATATYPE* cAddress);

The VB.NET code I translated is like this:

 <DllImport("MYDLL.dll")> Public Function Acquisition_GbIF_Init(ByRef HACQDESC As IntPtr, ByVal nChannelNr As Integer, ByVal bEnableIRQ As Boolean, ByVal uiRows As UInt32, ByVal uiColumns As UInt32, ByVal bSelfInit As Boolean, ByVal bAlwaysOpen As Boolean, ByVal lInitType As Long, ByRef cAddress As String) As Integer

 End Function

Here I should send be sending the value of "ucIP" which was declared as the structure member as:

  <MarshalAs(UnmanagedType.ByValTStr, sizeconst:=GBIF_IP_MAC_NAME_CHAR_ARRAY_LENGTH)> _
        Public ucIP As String

I think the problem is in defining the "cAddress" as "string" which instead is defined as "Unsigned Char" in VC++.
Or the other problem could be declaring the Handle "HACQDESC" as Intptr.
Orelse is there any problem in other parameters declaration?

[Niya]

Unable to find the entry point in the DLL has nothing to do with the function's signature. P/Invoke can't find the function at all which means the name maybe wrong. If it were the signature that was wrong then you would get a stack imbalance error. Make sure that you have the right function name.

[Susheelss]

Thanks Niya for your Valuable suggestions and replies.
The problem got solved. I replaced the datatype of "lInitType" declared as long to integer and the problem got solved.

[neemech]

Suseelss,

Could you please publish the code that worked?