C# Discussion Boards - CodeProject

savage_8-Jun-05 16:51

8-Jun-05 16:51

anyone know of a tool that can convert c/c++ header to c#, i need to
convert a massive struct which is about 150 lines that has nested
structs and unions.

heres a sample of the struct.
*note* chopped off bits and pieces in the middile.

struct R_OMNI_LINK_MESSAGE {
unsigned char MessageLength;
union {
unsigned char Data[255];
struct {
unsigned char MessageType;
union {
struct {
unsigned char ItemType8;
unsigned char ItemName8[16];
};
struct {
unsigned char TimeDateValidFlag;
unsigned char AreaSecurityMode[8]; // index 0-7
struct {
unsigned char BatteryReading;
} ExpansionEnclosure[8]; // index 0-7
};
struct /* olmMESSAGE_STATUS */ {
unsigned char Data;
} MessageStatus[33];
struct {
unsigned char AreaNumber; // (1-8)
};
struct {
unsigned char UserCodeNumber;
};
}; // union
}; // struct
}; // union
};

Kids don't try this at home!

Re: convert c/c++ header to c#

Christian Graus8-Jun-05 16:53

Christian Graus

8-Jun-05 16:53

There are no unions in C#.

Christian Graus - Microsoft MVP - C++

Re: convert c/c++ header to c#

savage_8-Jun-05 16:59

savage_

8-Jun-05 16:59

ok, how do i convert that to c#?

Kids don't try this at home!

Re: convert c/c++ header to c#

Christian Graus8-Jun-05 17:11

Christian Graus

8-Jun-05 17:11

I'm not sure that you can, in a way I'd consider production safe. Why do you need to ?

Christian Graus - Microsoft MVP - C++

Re: convert c/c++ header to c#

savage_8-Jun-05 17:20

savage_

8-Jun-05 17:20

doesnt matter if its safe or not...i just need it to work with c#, i have it partially converted but its giving me errors about [FieldOffset()] collisions and marshalling errors.

i need to convert this to c# so i can communicate with a piece of hardware, since i dont know enough c++, c# is the only way to go ;(

Kids don't try this at home!

Re: convert c/c++ header to c#

Christian Graus8-Jun-05 17:23

Christian Graus

8-Jun-05 17:23

savage_ wrote:
[FieldOffset()] collisions and marshalling errors.

Then you've found the methods I could suggest, I dunno how else you could do it. Excepting that perhaps you could store an object for each union, and then create objects that represent the possibilities that go inside. Honestly, I reckon it would be easier to learn a little C++.

Christian Graus - Microsoft MVP - C++

Re: convert c/c++ header to c# [EDITED]

Dave Kreskowiak9-Jun-05 8:49

Dave Kreskowiak

9-Jun-05 8:49

There is no tool that will do this for you. You'll have to code the thing by hand.

Since you haven't posted your C# code, it's impossible to tell you what you did wrong to generate that error. But, I'll take a guess at it.

Heath posted an example of how to simulate unions sometime last year. I grabbed this little piece of code from my archives:

[StructLayout(LayoutKind.Explicit)]
public struct INPUT{
  [FieldOffset(0), MarshalAs(UnmanagedType.U4)] public int type;
  [FieldOffset(4)] public MOUSEINPUT mi;
  [FieldOffset(4)] public KEYBOARDINPUT ki;
  // No need to declare HARDWAREINPUT since this is a union.
  // You would for proper bit alignment if it wasn't a union;
  // otherwise, you're shorting the execution stack.
}

[StructLayout(LayoutKind.Sequential)]
public struct MOUSEINPUT{
  public int dx; // Unmanaged longs are managed ints (both 32 bits)
  public int dy;
  [MarshalAs(UnmanagedType.U4)] public int mouseData;
  [MarshalAs(UnmanagedType.U4)] public int dwFlags;
  [MarshalAs(UnmanagedType.U4)] public int time;
  [MarshalAs(UnmanagedType.SysUInt)] public IntPtr dwExtraInfo;
}

[StructLayout(LayoutKind.Sequential)]
public struct KEYBOARDINPUT{
  public short wVk; // Could cast managed Keys enumeration to (short)
  public short wScan;
  [MarshalAs(UnmanagedType.U4)] public int dwFlags;
  [MarshalAs(UnmanagedType.U4)] public int time;
  [MarshalAs(UnmanagedType.SysUInt)] public IntPtr dwExtraInfo;
}

The thing to remember is that your inital struct must be LayoutKind.Explicit. Also note the FieldOffsets! If you use LayoutKind.Sequential and try using overlapping FieldOffsets, you'll get the collision exception.

Also, you're going to have to learn a little C++ to do this anyway. Since C++ types and .NET types of the same names don't exactly match in size or function.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

Re: convert c/c++ header to c# [EDITED]

savage_9-Jun-05 11:18

savage_

9-Jun-05 11:18

what i dont understand is the offsets. heres where im getting stuck:

struct R_OMNI_LINK_MESSAGE {
unsigned char messagelength // offset 0
unionX {
unsigned char data[255] // offset 4?
struct { // this struct has no name?
unsigned char messagetype // since its inside union this ones offset is 4?
unionY {
struct { // NAME_DATA
unsigned char itemtype // offset ??
} // struct name_data
} // unionY
} // struct
} // unionX
} // r_omni_link_message

this is my c# code for the above bit of code
[StructLayout(LayoutKind.Explicit)]
public struct R_OMNI_LINK_MESSAGE
{
[FieldOffset(0)] public int MessageLength;
[FieldOffset(4)][MarshalAs(UnmanagedType.ByValTStr, SizeConst=255)] public string Data;
[FieldOffset(??)] public int MessageType;

//olmNAME_DATA (8 bit)
[FieldOffset(??)][MarshalAs(UnmanagedType.LPStr)] public string ItemType8;
[FieldOffset(??)][MarshalAs(UnmanagedType.LPStr)] public string ItemNumber8;
[FieldOffset(??)][MarshalAs(UnmanagedType.LPStr, SizeConst=16)] public string ItemName8;

?? i dont know the offsets

Kids don't try this at home!

Re: convert c/c++ header to c# [EDITED]

Dave Kreskowiak9-Jun-05 15:24

Dave Kreskowiak

9-Jun-05 15:24

The field offsets are just how many bytes into the structure that field starts. What these values are depends on the original structure. Usually, the field offsets put the field immediately after the last one, accounting for the size (in bytes) of the previous fields.

In your example, the first field is an unsigned char, called messagelength, at, obviously, offset 0 from the start of the structure. Since the C++ char type is usually a single byte, the next field would probably be at offset 1, accounting for the size of the fields before it.

RageInTheMachine9532
"...a pungent, ghastly, stinky piece of cheese!" -- The Roaming Gnome

can someone explain this to me???

Serenena8-Jun-05 16:40

Serenena

8-Jun-05 16:40

i am enhancing a image button.... i found this web page but dun reali understand.... can someone teach me how to use it?

http://www.codeproject.com/script/comments/forums.asp?forumid=1649