P/Invoke structure question

[Duncan Mole]

Hi,

This is probably an easy one but it iy first bit of p/invoke. I am trying to
use the following C struct in a call:

typedef struct
{
BYTE SRB_Cmd;
BYTE SRB_Status,
BYTE SRB_HaId;
BYTE SRB_Flags;
DWORD SRB_Hdr_Rsvd;
BYTE HA_Count;
BYTE HA_SCSI_ID;
BYTE HA_ManagerId[16];
BYTE HA_Identifiyer[16];
BYTE HA_Unique[16];
BYTE HA_SRsvd1;
}
SRB_HAInquiry, *PSRB_HAInquiry ;

The function prototype is as follows:

SendASPI32Comma nd((LPSRB)&srbH AInquiry)

According to the docs LPSRB is 4 bit generic pointer to a command strucure.

Fort this I have:

[StructLayout(La youtKind.Sequen tial, CharSet=CharSet .Ansi)]

public class SRB_HAInquiry

{

public const int STRING_LEN = 16;

public byte SRB_Cmd;

public byte SRB_Status;

public byte SRB_HaId;

public byte SRB_Flags;

public UInt32 SRB_Hdr_Rsvd;

public byte HA_Count;

public byte HA_SCSI_ID;

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_ManagerId = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Identifier = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Unique = new string(' ', STRING_LEN);

public UInt16 HA_Rsvd1 = 0;

}

my invokke is :

[DllImport("wnas pi32.dll", EntryPoint="Sen dASPI32Command" ,

ExactSpelling=t rue, CharSet=CharSet .Ansi, SetLastError=tr ue)]

private static extern UInt32 SendASPI32Comma nd(

ref SRB_HAInquiry str);

and my call is:

public SRB_HAInquiry ScHaInquiry(int haId)

{

SRB_HAInquiry enq = new SRB_HAInquiry() ;

enq.SRB_Cmd = (byte)Commands. SC_HA_INQUIRY;

enq.SRB_HaId = (byte)haId;

UInt32 result = SendASPI32Comma nd(ref enq);
return enq;

}

Any help would be much appreciated.

[BMermuys]

Hi,

3 problems:

- You don't have to initialize the strings

- If you use a class as struct, then you don't have to pass it by reference,
objects are already passed by reference.
If you use a struct then you have to pass it by reference.

- HA_SRsvd1 is a BYTE inside the c structure and a Uint16 inside the managed
class, they don't match.
HTH,
greetings
"Duncan Mole" <du**********@n tlworld.com> wrote in message
news:L8******** *******@newsfe1-gui.ntli.net...

Hi,

This is probably an easy one but it iy first bit of p/invoke. I am trying to use the following C struct in a call:

typedef struct
{
BYTE SRB_Cmd;
BYTE SRB_Status,
BYTE SRB_HaId;
BYTE SRB_Flags;
DWORD SRB_Hdr_Rsvd;
BYTE HA_Count;
BYTE HA_SCSI_ID;
BYTE HA_ManagerId[16];
BYTE HA_Identifiyer[16];
BYTE HA_Unique[16];
BYTE HA_SRsvd1;
}
SRB_HAInquiry, *PSRB_HAInquiry ;

The function prototype is as follows:

SendASPI32Comma nd((LPSRB)&srbH AInquiry)

According to the docs LPSRB is 4 bit generic pointer to a command strucure.
Fort this I have:

[StructLayout(La youtKind.Sequen tial, CharSet=CharSet .Ansi)]

public class SRB_HAInquiry

{

public const int STRING_LEN = 16;

public byte SRB_Cmd;

public byte SRB_Status;

public byte SRB_HaId;

public byte SRB_Flags;

public UInt32 SRB_Hdr_Rsvd;

public byte HA_Count;

public byte HA_SCSI_ID;

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_ManagerId = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Identifier = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Unique = new string(' ', STRING_LEN);

public UInt16 HA_Rsvd1 = 0;

}

my invokke is :

[DllImport("wnas pi32.dll", EntryPoint="Sen dASPI32Command" ,

ExactSpelling=t rue, CharSet=CharSet .Ansi, SetLastError=tr ue)]

private static extern UInt32 SendASPI32Comma nd(

ref SRB_HAInquiry str);

and my call is:

public SRB_HAInquiry ScHaInquiry(int haId)

{

SRB_HAInquiry enq = new SRB_HAInquiry() ;

enq.SRB_Cmd = (byte)Commands. SC_HA_INQUIRY;

enq.SRB_HaId = (byte)haId;

UInt32 result = SendASPI32Comma nd(ref enq);
return enq;

}

Any help would be much appreciated.

[Chua Wen Ching]

Hi Duncan Mole,

So just wondering, what is the problem? Do you face any problems? Is yes, mind to share us the errors?

Thanks. Sorry for the trouble.
--
Regards,
Chua Wen Ching :)
"Duncan Mole" wrote:

Hi,

This is probably an easy one but it iy first bit of p/invoke. I am trying to
use the following C struct in a call:

typedef struct
{
BYTE SRB_Cmd;
BYTE SRB_Status,
BYTE SRB_HaId;
BYTE SRB_Flags;
DWORD SRB_Hdr_Rsvd;
BYTE HA_Count;
BYTE HA_SCSI_ID;
BYTE HA_ManagerId[16];
BYTE HA_Identifiyer[16];
BYTE HA_Unique[16];
BYTE HA_SRsvd1;
}
SRB_HAInquiry, *PSRB_HAInquiry ;

The function prototype is as follows:

SendASPI32Comma nd((LPSRB)&srbH AInquiry)

According to the docs LPSRB is 4 bit generic pointer to a command strucure.

Fort this I have:

[StructLayout(La youtKind.Sequen tial, CharSet=CharSet .Ansi)]

public class SRB_HAInquiry

{

public const int STRING_LEN = 16;

public byte SRB_Cmd;

public byte SRB_Status;

public byte SRB_HaId;

public byte SRB_Flags;

public UInt32 SRB_Hdr_Rsvd;

public byte HA_Count;

public byte HA_SCSI_ID;

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_ManagerId = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Identifier = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Unique = new string(' ', STRING_LEN);

public UInt16 HA_Rsvd1 = 0;

}

my invokke is :

[DllImport("wnas pi32.dll", EntryPoint="Sen dASPI32Command" ,

ExactSpelling=t rue, CharSet=CharSet .Ansi, SetLastError=tr ue)]

private static extern UInt32 SendASPI32Comma nd(

ref SRB_HAInquiry str);

and my call is:

public SRB_HAInquiry ScHaInquiry(int haId)

{

SRB_HAInquiry enq = new SRB_HAInquiry() ;

enq.SRB_Cmd = (byte)Commands. SC_HA_INQUIRY;

enq.SRB_HaId = (byte)haId;

UInt32 result = SendASPI32Comma nd(ref enq);
return enq;

}

Any help would be much appreciated.

[Irfan]

Hi,

I too had a similar problem with the structure containing
a string array variable.

Better see if you run your application on .NET 1.1 as that
solved mine.

Thanks,
irfan

[Chua Wen Ching]

Hi BMermuys,

What if i have a structure like this?

typedef unsigned short uint16;

typedef uint16 *puint16;

typedef struct StructA
{
puint16 Data;
} StructTest;

Any idea how to do this in C#?

Thanks.
--
Regards,
Chua Wen Ching :)
"BMermuys" wrote:

Hi,

3 problems:

- You don't have to initialize the strings

- If you use a class as struct, then you don't have to pass it by reference,
objects are already passed by reference.
If you use a struct then you have to pass it by reference.

- HA_SRsvd1 is a BYTE inside the c structure and a Uint16 inside the managed
class, they don't match.
HTH,
greetings
"Duncan Mole" <du**********@n tlworld.com> wrote in message
news:L8******** *******@newsfe1-gui.ntli.net...

Hi,

This is probably an easy one but it iy first bit of p/invoke. I am trying

to

use the following C struct in a call:

typedef struct
{
BYTE SRB_Cmd;
BYTE SRB_Status,
BYTE SRB_HaId;
BYTE SRB_Flags;
DWORD SRB_Hdr_Rsvd;
BYTE HA_Count;
BYTE HA_SCSI_ID;
BYTE HA_ManagerId[16];
BYTE HA_Identifiyer[16];
BYTE HA_Unique[16];
BYTE HA_SRsvd1;
}
SRB_HAInquiry, *PSRB_HAInquiry ;

The function prototype is as follows:

SendASPI32Comma nd((LPSRB)&srbH AInquiry)

According to the docs LPSRB is 4 bit generic pointer to a command

strucure.

Fort this I have:

[StructLayout(La youtKind.Sequen tial, CharSet=CharSet .Ansi)]

public class SRB_HAInquiry

{

public const int STRING_LEN = 16;

public byte SRB_Cmd;

public byte SRB_Status;

public byte SRB_HaId;

public byte SRB_Flags;

public UInt32 SRB_Hdr_Rsvd;

public byte HA_Count;

public byte HA_SCSI_ID;

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_ManagerId = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Identifier = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Unique = new string(' ', STRING_LEN);

public UInt16 HA_Rsvd1 = 0;

}

my invokke is :

[DllImport("wnas pi32.dll", EntryPoint="Sen dASPI32Command" ,

ExactSpelling=t rue, CharSet=CharSet .Ansi, SetLastError=tr ue)]

private static extern UInt32 SendASPI32Comma nd(

ref SRB_HAInquiry str);

and my call is:

public SRB_HAInquiry ScHaInquiry(int haId)

{

SRB_HAInquiry enq = new SRB_HAInquiry() ;

enq.SRB_Cmd = (byte)Commands. SC_HA_INQUIRY;

enq.SRB_HaId = (byte)haId;

UInt32 result = SendASPI32Comma nd(ref enq);
return enq;

}

Any help would be much appreciated.

[BMermuys]

Hi,
[inline]

"Chua Wen Ching" <ch************ @nospam.hotmail .com> wrote in message
news:36******** *************** ***********@mic rosoft.com...

Hi BMermuys,

What if i have a structure like this?

typedef unsigned short uint16;

typedef uint16 *puint16;

typedef struct StructA
{
puint16 Data;
} StructTest;
[StructLayout(La youtKind.Sequen tial)]
public struct StructTest
{
IntPtr pData; // PUSHORT
}

Here you end up with the "pointer-problem". If you work with pointers, you
should think about allocating and de-allocating memory.

Think about:
1. The side (managed or unmanaged) that allocates the memory for the
ushort should also de-allocate it.
2. This also means that the side that initial set the pointer can only
change it (re-allocation).
3. After allocation happened, any side can change the value the pointer
points to, that's no problem.
Example allocating memory from c# and de-allocating from c#:
----
StructTest myStruct = new StructTest();
myStruct.pData = Marshal.AllocHG lobal(sizeof(ty peof(ushort));
//allocation

// eg write to it
ushort x = 100;
Marshal.WriteIn t16( myStruct.pData, (short) x );

// suppose here you call an unmanaged function that alters (*pData), it
shouldn't change the pointer,
// then you can get the new value:
x = (ushort)Marshal .ReadInt16( myStruct.pData );

Marshal.FreeHGl obal( myStruct.pData );
//de-allocation
HTH,
greetings

Any idea how to do this in C#?

Thanks.
--
Regards,
Chua Wen Ching :)
"BMermuys" wrote:

Hi,

3 problems:

- You don't have to initialize the strings

- If you use a class as struct, then you don't have to pass it by reference, objects are already passed by reference.
If you use a struct then you have to pass it by reference.

- HA_SRsvd1 is a BYTE inside the c structure and a Uint16 inside the managed class, they don't match.
HTH,
greetings
"Duncan Mole" <du**********@n tlworld.com> wrote in message
news:L8******** *******@newsfe1-gui.ntli.net...

Hi,

This is probably an easy one but it iy first bit of p/invoke. I am

trying to

use the following C struct in a call:

typedef struct
{
BYTE SRB_Cmd;
BYTE SRB_Status,
BYTE SRB_HaId;
BYTE SRB_Flags;
DWORD SRB_Hdr_Rsvd;
BYTE HA_Count;
BYTE HA_SCSI_ID;
BYTE HA_ManagerId[16];
BYTE HA_Identifiyer[16];
BYTE HA_Unique[16];
BYTE HA_SRsvd1;
}
SRB_HAInquiry, *PSRB_HAInquiry ;

The function prototype is as follows:

SendASPI32Comma nd((LPSRB)&srbH AInquiry)

According to the docs LPSRB is 4 bit generic pointer to a command

strucure.

Fort this I have:

[StructLayout(La youtKind.Sequen tial, CharSet=CharSet .Ansi)]

public class SRB_HAInquiry

{

public const int STRING_LEN = 16;

public byte SRB_Cmd;

public byte SRB_Status;

public byte SRB_HaId;

public byte SRB_Flags;

public UInt32 SRB_Hdr_Rsvd;

public byte HA_Count;

public byte HA_SCSI_ID;

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_ManagerId = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Identifier = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Unique = new string(' ', STRING_LEN);

public UInt16 HA_Rsvd1 = 0;

}

my invokke is :

[DllImport("wnas pi32.dll", EntryPoint="Sen dASPI32Command" ,

ExactSpelling=t rue, CharSet=CharSet .Ansi, SetLastError=tr ue)]

private static extern UInt32 SendASPI32Comma nd(

ref SRB_HAInquiry str);

and my call is:

public SRB_HAInquiry ScHaInquiry(int haId)

{

SRB_HAInquiry enq = new SRB_HAInquiry() ;

enq.SRB_Cmd = (byte)Commands. SC_HA_INQUIRY;

enq.SRB_HaId = (byte)haId;

UInt32 result = SendASPI32Comma nd(ref enq);
return enq;

}

Any help would be much appreciated.

[Duncan Mole]

Hi BMermuys,

Thanks for the response. I wrote it last last night, trying new tricks that
late is never a good idea! I look forward to making the fixes you have
flagged when I get home tonight, interestingly HA_SRsvd1 was the only member
whose value changed - hopefully this is a good sign! I'll post my results to
this thread.

Duncan
"BMermuys" <so*****@someon e.com> wrote in message
news:Mw******** **************@ phobos.telenet-ops.be...

Hi,

3 problems:

- You don't have to initialize the strings

- If you use a class as struct, then you don't have to pass it by reference, objects are already passed by reference.
If you use a struct then you have to pass it by reference.

- HA_SRsvd1 is a BYTE inside the c structure and a Uint16 inside the managed class, they don't match.
HTH,
greetings
"Duncan Mole" <du**********@n tlworld.com> wrote in message
news:L8******** *******@newsfe1-gui.ntli.net...

Hi,

This is probably an easy one but it iy first bit of p/invoke. I am

trying to

use the following C struct in a call:

typedef struct
{
BYTE SRB_Cmd;
BYTE SRB_Status,
BYTE SRB_HaId;
BYTE SRB_Flags;
DWORD SRB_Hdr_Rsvd;
BYTE HA_Count;
BYTE HA_SCSI_ID;
BYTE HA_ManagerId[16];
BYTE HA_Identifiyer[16];
BYTE HA_Unique[16];
BYTE HA_SRsvd1;
}
SRB_HAInquiry, *PSRB_HAInquiry ;

The function prototype is as follows:

SendASPI32Comma nd((LPSRB)&srbH AInquiry)

According to the docs LPSRB is 4 bit generic pointer to a command

strucure.

Fort this I have:

[StructLayout(La youtKind.Sequen tial, CharSet=CharSet .Ansi)]

public class SRB_HAInquiry

{

public const int STRING_LEN = 16;

public byte SRB_Cmd;

public byte SRB_Status;

public byte SRB_HaId;

public byte SRB_Flags;

public UInt32 SRB_Hdr_Rsvd;

public byte HA_Count;

public byte HA_SCSI_ID;

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_ManagerId = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Identifier = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Unique = new string(' ', STRING_LEN);

public UInt16 HA_Rsvd1 = 0;

}

my invokke is :

[DllImport("wnas pi32.dll", EntryPoint="Sen dASPI32Command" ,

ExactSpelling=t rue, CharSet=CharSet .Ansi, SetLastError=tr ue)]

private static extern UInt32 SendASPI32Comma nd(

ref SRB_HAInquiry str);

and my call is:

public SRB_HAInquiry ScHaInquiry(int haId)

{

SRB_HAInquiry enq = new SRB_HAInquiry() ;

enq.SRB_Cmd = (byte)Commands. SC_HA_INQUIRY;

enq.SRB_HaId = (byte)haId;

UInt32 result = SendASPI32Comma nd(ref enq);
return enq;

}

Any help would be much appreciated.

[Duncan Mole]

Hi BMermuys,

Well, unfortuantley the changes did not help. None of the fields are being
set, this I can confirm becase SRB_Status is supposed to be set to the
return value of SendASPI32Comma nd and it isn't. With regards to HA_SRsvd1 ,
this was a mistake in the post, it is acually a WORD.

Any other ideas?

"Duncan Mole" <___@____.com > wrote in message
news:Ox******** ******@TK2MSFTN GP11.phx.gbl...

Hi BMermuys,

Thanks for the response. I wrote it last last night, trying new tricks that late is never a good idea! I look forward to making the fixes you have
flagged when I get home tonight, interestingly HA_SRsvd1 was the only member whose value changed - hopefully this is a good sign! I'll post my results to this thread.

Duncan
"BMermuys" <so*****@someon e.com> wrote in message
news:Mw******** **************@ phobos.telenet-ops.be...

Hi,

3 problems:

- You don't have to initialize the strings

- If you use a class as struct, then you don't have to pass it by

reference,

objects are already passed by reference.
If you use a struct then you have to pass it by reference.

- HA_SRsvd1 is a BYTE inside the c structure and a Uint16 inside the

managed

class, they don't match.
HTH,
greetings
"Duncan Mole" <du**********@n tlworld.com> wrote in message
news:L8******** *******@newsfe1-gui.ntli.net...

Hi,

This is probably an easy one but it iy first bit of p/invoke. I am

trying

to

use the following C struct in a call:

typedef struct
{
BYTE SRB_Cmd;
BYTE SRB_Status,
BYTE SRB_HaId;
BYTE SRB_Flags;
DWORD SRB_Hdr_Rsvd;
BYTE HA_Count;
BYTE HA_SCSI_ID;
BYTE HA_ManagerId[16];
BYTE HA_Identifiyer[16];
BYTE HA_Unique[16];
BYTE HA_SRsvd1;
}
SRB_HAInquiry, *PSRB_HAInquiry ;

The function prototype is as follows:

SendASPI32Comma nd((LPSRB)&srbH AInquiry)

According to the docs LPSRB is 4 bit generic pointer to a command

strucure.

Fort this I have:

[StructLayout(La youtKind.Sequen tial, CharSet=CharSet .Ansi)]

public class SRB_HAInquiry

{

public const int STRING_LEN = 16;

public byte SRB_Cmd;

public byte SRB_Status;

public byte SRB_HaId;

public byte SRB_Flags;

public UInt32 SRB_Hdr_Rsvd;

public byte HA_Count;

public byte HA_SCSI_ID;

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_ManagerId = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Identifier = new string(' ', STRING_LEN);

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]

public string HA_Unique = new string(' ', STRING_LEN);

public UInt16 HA_Rsvd1 = 0;

}

my invokke is :

[DllImport("wnas pi32.dll", EntryPoint="Sen dASPI32Command" ,

ExactSpelling=t rue, CharSet=CharSet .Ansi, SetLastError=tr ue)]

private static extern UInt32 SendASPI32Comma nd(

ref SRB_HAInquiry str);

and my call is:

public SRB_HAInquiry ScHaInquiry(int haId)

{

SRB_HAInquiry enq = new SRB_HAInquiry() ;

enq.SRB_Cmd = (byte)Commands. SC_HA_INQUIRY;

enq.SRB_HaId = (byte)haId;

UInt32 result = SendASPI32Comma nd(ref enq);
return enq;

}

Any help would be much appreciated.

[BMermuys]

Hi,

"Duncan Mole" <du**********@n tlworld.com> wrote in message
news:8f******** *******@newsfe1-gui.ntli.net...

Hi BMermuys,

Well, unfortuantley the changes did not help. None of the fields are being
set, this I can confirm becase SRB_Status is supposed to be set to the
return value of SendASPI32Comma nd and it isn't. With regards to HA_SRsvd1 , this was a mistake in the post, it is acually a WORD.
I always use a struct not a class. A quick test using a class as a struct
failed when an inline array is used, I gonna look into that later.

In the meantime if you didn't already tried it, try using a struct. This
should work, if it doesn't check if the function doesn't return an error and
check if you can call it succesfully from c.

[StructLayout(La youtKind.Sequen tial, CharSet=CharSet .Ansi)]
public struct SRB_HAInquiry
{
public const int STRING_LEN = 16;
public byte SRB_Cmd;
public byte SRB_Status;
public byte SRB_HaId;
public byte SRB_Flags;
public uint SRB_Hdr_Rsvd;
public byte HA_Count;
public byte HA_SCSI_ID;

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]
public string HA_ManagerId;

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]
public string HA_Identifier;

[MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]
public string HA_Unique;

public ushort HA_Rsvd1;
}

[DllImport("wnas pi32.dll", EntryPoint="Sen dASPI32Command" ,
ExactSpelling=t rue, CharSet=CharSet .Ansi, SetLastError=tr ue)]
private static extern UInt32 SendASPI32Comma nd(ref SRB_HAInquiry str);

HTH,
greetings

Any other ideas?

"Duncan Mole" <___@____.com > wrote in message
news:Ox******** ******@TK2MSFTN GP11.phx.gbl...

Hi BMermuys,

Thanks for the response. I wrote it last last night, trying new tricks that

late is never a good idea! I look forward to making the fixes you have
flagged when I get home tonight, interestingly HA_SRsvd1 was the only

member

whose value changed - hopefully this is a good sign! I'll post my

results to

this thread.

Duncan
"BMermuys" <so*****@someon e.com> wrote in message
news:Mw******** **************@ phobos.telenet-ops.be...

Hi,

3 problems:

- You don't have to initialize the strings

- If you use a class as struct, then you don't have to pass it by

reference,

objects are already passed by reference.
If you use a struct then you have to pass it by reference.

- HA_SRsvd1 is a BYTE inside the c structure and a Uint16 inside the

managed

class, they don't match.
HTH,
greetings
"Duncan Mole" <du**********@n tlworld.com> wrote in message
news:L8******** *******@newsfe1-gui.ntli.net...
> Hi,
>
> This is probably an easy one but it iy first bit of p/invoke. I am

trying

to
> use the following C struct in a call:
>
> typedef struct
> {
> BYTE SRB_Cmd;
> BYTE SRB_Status,
> BYTE SRB_HaId;
> BYTE SRB_Flags;
> DWORD SRB_Hdr_Rsvd;
> BYTE HA_Count;
> BYTE HA_SCSI_ID;
> BYTE HA_ManagerId[16];
> BYTE HA_Identifiyer[16];
> BYTE HA_Unique[16];
> BYTE HA_SRsvd1;
> }
> SRB_HAInquiry, *PSRB_HAInquiry ;
>
> The function prototype is as follows:
>
> SendASPI32Comma nd((LPSRB)&srbH AInquiry)
>
> According to the docs LPSRB is 4 bit generic pointer to a command
strucure.
>
> Fort this I have:
>
> [StructLayout(La youtKind.Sequen tial, CharSet=CharSet .Ansi)]
>
> public class SRB_HAInquiry
>
> {
>
> public const int STRING_LEN = 16;
>
> public byte SRB_Cmd;
>
> public byte SRB_Status;
>
> public byte SRB_HaId;
>
> public byte SRB_Flags;
>
> public UInt32 SRB_Hdr_Rsvd;
>
> public byte HA_Count;
>
> public byte HA_SCSI_ID;
>
> [MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]
>
> public string HA_ManagerId = new string(' ', STRING_LEN);
>
> [MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]
>
> public string HA_Identifier = new string(' ', STRING_LEN);
>
> [MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]
>
> public string HA_Unique = new string(' ', STRING_LEN);
>
> public UInt16 HA_Rsvd1 = 0;
>
> }
>
> my invokke is :
>
> [DllImport("wnas pi32.dll", EntryPoint="Sen dASPI32Command" ,
>
> ExactSpelling=t rue, CharSet=CharSet .Ansi, SetLastError=tr ue)]
>
> private static extern UInt32 SendASPI32Comma nd(
>
> ref SRB_HAInquiry str);
>
>
>
> and my call is:
>
>
>
> public SRB_HAInquiry ScHaInquiry(int haId)
>
> {
>
> SRB_HAInquiry enq = new SRB_HAInquiry() ;
>
> enq.SRB_Cmd = (byte)Commands. SC_HA_INQUIRY;
>
> enq.SRB_HaId = (byte)haId;
>
> UInt32 result = SendASPI32Comma nd(ref enq);
>
>
> return enq;
>
> }
>
> Any help would be much appreciated.
>
>
>
>

[Chua Wen Ching]

Hi BMermuys,

Wow. Thanks a lot. I always thought IntPtr is for integer. Not sure can be done with ushort. Had been thinking of using other ways. I had few doubts. Maybe you can help me to clarify it. Thanks.

From your code:
--------------------
// eg write to it
ushort x = 100;
Marshal.WriteIn t16( myStruct.pData, (short) x );

--> Is this to write 100 value to myStruct.pData?

// suppose here you call an unmanaged function that alters (*pData), it
shouldn't change the pointer,
// then you can get the new value:
x = (ushort)Marshal .ReadInt16( myStruct.pData );

--> I assume if we use *pData, normally we expect the out value there. So it also means you are transfering the *pData out value to x.

Marshal.FreeHGl obal( myStruct.pData );
//de-allocation

--> Is it always a must to do the de-allocation?

Wow, if i had this:

struct StructTest
{
int Var1;
int Var2;
float Var3;
IntPtr pData;
IntPtr pHeader;
IntPtr pBits;
}

--> So i declare IntPtr for 3 times, had to marshal for 3 times and deallocated for 3 times. Is that right?

--> I am also curious about UIntPtr. I saw this before. What is the difference between UIntPtr and IntPtr. Why can't i use UIntPtr, as i am using unsigned short pointer.

--> Is there any good resources to pick up marshalling for this kind of scenario. I am always looking forward on this, but I am not sure what is the right keywords to search in the Internet.

Thanks again for the wonderful tips.

--
Regards,
Chua Wen Ching :)
"BMermuys" wrote:

Hi,
[inline]

"Chua Wen Ching" <ch************ @nospam.hotmail .com> wrote in message
news:36******** *************** ***********@mic rosoft.com...

Hi BMermuys,

What if i have a structure like this?

typedef unsigned short uint16;

typedef uint16 *puint16;

typedef struct StructA
{
puint16 Data;
} StructTest;

[StructLayout(La youtKind.Sequen tial)]
public struct StructTest
{
IntPtr pData; // PUSHORT
}

Here you end up with the "pointer-problem". If you work with pointers, you
should think about allocating and de-allocating memory.

Think about:
1. The side (managed or unmanaged) that allocates the memory for the
ushort should also de-allocate it.
2. This also means that the side that initial set the pointer can only
change it (re-allocation).
3. After allocation happened, any side can change the value the pointer
points to, that's no problem.
Example allocating memory from c# and de-allocating from c#:
----
StructTest myStruct = new StructTest();
myStruct.pData = Marshal.AllocHG lobal(sizeof(ty peof(ushort));
//allocation

// eg write to it
ushort x = 100;
Marshal.WriteIn t16( myStruct.pData, (short) x );

// suppose here you call an unmanaged function that alters (*pData), it
shouldn't change the pointer,
// then you can get the new value:
x = (ushort)Marshal .ReadInt16( myStruct.pData );

Marshal.FreeHGl obal( myStruct.pData );
//de-allocation
HTH,
greetings

Any idea how to do this in C#?

Thanks.
--
Regards,
Chua Wen Ching :)
"BMermuys" wrote:

Hi,

3 problems:

- You don't have to initialize the strings

- If you use a class as struct, then you don't have to pass it by reference, objects are already passed by reference.
If you use a struct then you have to pass it by reference.

- HA_SRsvd1 is a BYTE inside the c structure and a Uint16 inside the managed class, they don't match.
HTH,
greetings
"Duncan Mole" <du**********@n tlworld.com> wrote in message
news:L8******** *******@newsfe1-gui.ntli.net...
> Hi,
>
> This is probably an easy one but it iy first bit of p/invoke. I am trying to
> use the following C struct in a call:
>
> typedef struct
> {
> BYTE SRB_Cmd;
> BYTE SRB_Status,
> BYTE SRB_HaId;
> BYTE SRB_Flags;
> DWORD SRB_Hdr_Rsvd;
> BYTE HA_Count;
> BYTE HA_SCSI_ID;
> BYTE HA_ManagerId[16];
> BYTE HA_Identifiyer[16];
> BYTE HA_Unique[16];
> BYTE HA_SRsvd1;
> }
> SRB_HAInquiry, *PSRB_HAInquiry ;
>
> The function prototype is as follows:
>
> SendASPI32Comma nd((LPSRB)&srbH AInquiry)
>
> According to the docs LPSRB is 4 bit generic pointer to a command
strucure.
>
> Fort this I have:
>
> [StructLayout(La youtKind.Sequen tial, CharSet=CharSet .Ansi)]
>
> public class SRB_HAInquiry
>
> {
>
> public const int STRING_LEN = 16;
>
> public byte SRB_Cmd;
>
> public byte SRB_Status;
>
> public byte SRB_HaId;
>
> public byte SRB_Flags;
>
> public UInt32 SRB_Hdr_Rsvd;
>
> public byte HA_Count;
>
> public byte HA_SCSI_ID;
>
> [MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]
>
> public string HA_ManagerId = new string(' ', STRING_LEN);
>
> [MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]
>
> public string HA_Identifier = new string(' ', STRING_LEN);
>
> [MarshalAs(Unman agedType.ByValT Str, SizeConst=STRIN G_LEN)]
>
> public string HA_Unique = new string(' ', STRING_LEN);
>
> public UInt16 HA_Rsvd1 = 0;
>
> }
>
> my invokke is :
>
> [DllImport("wnas pi32.dll", EntryPoint="Sen dASPI32Command" ,
>
> ExactSpelling=t rue, CharSet=CharSet .Ansi, SetLastError=tr ue)]
>
> private static extern UInt32 SendASPI32Comma nd(
>
> ref SRB_HAInquiry str);
>
>
>
> and my call is:
>
>
>
> public SRB_HAInquiry ScHaInquiry(int haId)
>
> {
>
> SRB_HAInquiry enq = new SRB_HAInquiry() ;
>
> enq.SRB_Cmd = (byte)Commands. SC_HA_INQUIRY;
>
> enq.SRB_HaId = (byte)haId;
>
> UInt32 result = SendASPI32Comma nd(ref enq);
>
>
> return enq;
>
> }
>
> Any help would be much appreciated.
>
>
>
>