New year – new blog or how to migrate Community Server to any other engine, supports XML-RPC

Tamir Khason — Fri, 02 Jan 2009 02:33:04 GMT

Please update your bookmarks, because the new url of this blog is http://khason.net/ (you have not update RSS feeds, it will be done automatically). Why I did it? Why I decided to go to “stand-alone”… Well. there are some reasons. Generally, I do not want to explain all those here, but trust me, there are some. The main reason is, that there is no responsible person in charge for this blog platform in Microsoft Israel. This why, if your blog is popular and you have a respect to your blog visitors, you cannot host it here… Take a look into new comments notifications in my inbox. Would you answer your readers with such “small amount” of SPAM and capcha, that cannot be fixed already for three years in this platform? This how my inbox looks like for last three years. So now, you should not ask me, why I not answered your email or comments. Aren’t you? :)

Currently, all comments in this blog are disabled, so if you want to comment, please use new url of posts (this will appear shortly in the beginning of each post). Also, this post will not be syndicated in RSS.

So, this post is the last. I loved this platform, and loved people started it. But, unfortunately, it seemed, that bloggers community is not important enough for new platform managers.

Also, If you want to learn how to use C# and XML-RCP to migrate from CS2007, used in this platform, visit my new home :)

Have a great year and, as always, be good people. This post marked with all possible tags automatically. Sorry.

P/Invoke cheat sheet

Tamir Khason — Mon, 20 Oct 2008 20:02:40 GMT

[This blog was migrated. You will not be able to comment here.
The new URL of this post is http://khason.net/blog/pinvoke-cheat-sheet/]

I’m working a lot with p/invoke, and know how it’s hard to produce correct signature for unmanaged method. So, today I decided to publish basic cheat sheet for methods, parameters and attributes you should use in order to invoke unmanaged methods from managed code without a lot of problems. We start with data type translations. Here the table to understand it.

Data type from unmanaged signature	Data type in managed signature
int	int the same with all other simple types such as double, uint, etc or private objects
void*	IntPtr
int*	ref int the same with all other simple types such as double, uint, etc or private objects
char**	ref IntPtr later, you should get ascii string by using System.Runtime.InteropServices.Marshal.PtrToStringAnsi() method
wcar_t**	ref IntPtr later, you should get ascii string by using System.Runtime.InteropServices.Marshal.PtrToStringUni() method
const int*	ref int
const char*	[System.Runtime.InteropServices.In()] [System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.LPWStr)] string
… (variable argument)	[System.Runtime.InteropServices.In()] [System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.AsAny)] object

You can use either System.Runtime.InteropServices.In or System.Runtime.InteropServices.Out attribute to specify how arguments should be used.

Now we done with simple arguments, let’s see what can be done when argument is actually callback or delegate?

Unmanaged definition

Managed definition

typedef void (*MyCallback)(int Arg)

[System.Runtime.InteropServices.UnmanagedFunctionPointer(System.Runtime.InteropServices.CallingConvention.Cdecl)]delegate void MyCallback(int Arg)
Caller cleans stack argument is used to assure, that we can call varargs type function, usually used by API provider. It is very similar to C# overrides for methods. Also you can use StdCall (this is default), ThisCall – stores this first and pushes other parameters on the stack, FastCall – not very supported :(

To call all those methods, we should know managed equivalents of unmanaged types. Here the table. The rule is simple – know how many bytes unmanaged type has and find managed type with the same number of bytes. Other words, you can marshal int into IntPtr too…

Unmanaged type	Managed equivalent
bool	bool
char	sbyte (signed), byte (unsigned)
wchar_t	char
double	double
float	single
int, long (signed)	Int32
int, long (unsigned)	UInt32
__int64 (signed)	Int64
__int64	UInt64
short (signed)	Int16
short (unsigned)	UInt16
void	void

But not only types are problem in managed/unmanaged transitions. Also structures are aligned differently. For this purpose we can use StructLayout attribute. Even if unmanaged classes are sequential and you used correct managed data types, you can find you with problems in Pack. What “pack” is? Pack is actually slot size in bytes for members of your structure. It can be 0, 1, 2, 4, 8, 16, 32, 64, or 128 and depends on the platform and application setting.

Now you can see, that it is not very complicated to create managed signatures when you have header of unmanaged assemblies. So go ahead and ask, if I missed something.

That’s all by now. Have a nice day and be good people.

Just code - Tamir Khason : DEV, Mono

New year – new blog or how to migrate Community Server to any other engine, supports XML-RPC

P/Invoke cheat sheet

[This blog was migrated. You will not be able to comment here.The new URL of this post is http://khason.net/blog/pinvoke-cheat-sheet/]

[This blog was migrated. You will not be able to comment here.
The new URL of this post is http://khason.net/blog/pinvoke-cheat-sheet/]