C# P/Invoke

Question

5.00/5 (1 vote)

See more:

I was wondering if I could invoke directly in C# assembly code (i must optimize a loop which involves some math computations and I was thinking I should write them in assembly to speed it up).
However, I'ved google'it and all I could find was some sort of invoking the assembly code in C and then using P/Invoke in C# .
Is there a way that I could invoke the assembly directly from C#?

Thanks in advance !

Posted 25-Dec-10 8:28am

tamash_ionut

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Phil J Pearson · Answer 1 · 2010-12-25T08:59:00

Solution 1

It would be quite possible to write a dll in assembly language and P/Invoke that from C# but you would be making life inordinately difficult for yourself.

I would just hack together a dll in C++ and write the assembler stuff in there.

Posted 25-Dec-10 8:59am

Phil J Pearson

Comments

Sergey Alexandrovich Kryukov 25-Dec-10 15:44pm

Yes, Phil, you're right. I totally agree.

Sergey Alexandrovich Kryukov 25-Dec-10 15:47pm

...and, after all, one could also insert in-line assembly in that C++ code if it even makes any sense. In this case, mixed-mode target (both native and CLR) should be used for C++ project.

Sergey Alexandrovich Kryukov · Answer 2 · 2010-12-25T09:25:00

As creating a library from Assembly Language source code and using P/Invoke to link it to C# project is already direct enough ;), I think what you have in mind is something like "inline assembly" available in C++ or Borland Pascal/Delphi code.

In this way, you could actually mix C# and assembly code, but -- no, you can't, but you should better understand why not and also understand that you really don't want it.

You can not do such thing, because .NET assembly is not compiled in any CPU's code. The compilation is done by JIT when the code is already loaded; and this is done gradually, on per-method basis (so, for example, method which never called will not be compiled). This makes things amazingly portable. A good deal of my applications I develop I also run on Linux, even UI applications. The assembly has target CPUs specified in it; and it can be some class of Intel CPU (x86 (32-bit architecture), x86-64 and Itanium (two different 64-bit architectures)), but this is no more than a simple "tag" in the executable image; and the default is "Any CPU" (using auto-detected CPU);

If "inline assembly" existed its code would not get a target to be compiled into.

(Well, I could fantasize remote possibility that such high-level .NET language with "inline assembly" feature can be created, but all it could do is automating process of creating if native assembly in linking is using PInvoke. I don't think there will be any practical justification for such work.)

Don't confuse, however, assembly language with IL. Yes, any assembly can be "disassembled" into IL, so IL plays a role of Assembly Language in the word of .NET in that sense it is low-level. IL also target .NET byte code (it actually a text human-readable representation of the byte code resembling tradition Assembly Language), it does not target CPU instruction code.

You could also optimize IL code and compile it back. There are few interesting and useful works where people automatically disassemble an assembly, tweak IL code and assemble it back during build step behind the scene. This is because IL has some features not available in other languages, and because with IL you can gain more fine-grain control.

I don't think it can give you much. I would advice to try regular P/Invoke.
Good luck!