FASM in C#

[Jens]

I recently decided that copy / pasting memory patches to use in my framework was really tedious, so I decided to get FASM to work in C# since i could not be bothered to use fasm_managed, since it is in C++/CLI and therefore the devil.

This is a just a simple .cs file, containing the necessary code to call fasm_assemble from the FASM library (less than 30 lines of code)

The only purpose of this code was to assemble asm to bytes, it does not contain code to write the bytes to memory or call asm procedures, it is all trivial to implement though.

Have a look at it here.

Usage:

string asm = @"push ebp
	       mov ebp, esp

	       mov esp, ebp
	       pop ebp

	       ret";

try
{
	byte[] bytes = Asm.Assemble(asm);

	foreach (var b in bytes)
	{
		Console.Write(b.ToString("X2") + " ");
	}
}
catch (Exception e)
{
	Console.WriteLine(e.Message);
}

Console.Read();

Error examples:

Assembling failed!
State:  FASM_ERROR
Error:  FASMERR_ILLEGAL_INSTRUCTION
line:   5

Assembling failed!
State:  FASM_ERROR
Error:  FASMERR_INVALID_OPERAND
line:   4

Remember to include the FASM library in your output directory, or wherever you decide to call it from, otherwise bad things will happen.

If you would like to get FASM library yourself, you can get it here, remember to change the DllImport according to the name of the assembly.


Credits:
- Shynd for fasm_managed, the C++/CLI wrapper for FASM
- Tomasz Grysztar for FASM


Enjoy.

[nableng]

c# and asm... srsly?

[Jens]

c# and asm... srsly?

Everything (!) should be done in C#

[berlinermauer]

Hint: Let the first line be "use32" or else you will expecting Problems as all your addresses and registers are considered 16bits

[Jens]

Hint: Let the first line be "use32" or else you will expecting Problems as all your addresses and registers are considered 16bits

Is added automatically, since it's a bother to do that every time you want to assemble something.