Calling and DLL

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denial

Joined: 12 Sep 2004
Posts: 98

denial 06 Jan 2005, 16:40

I tried to import GetTickCount() inside the Kernel32.DLL with the import macro.
I did it as always and tried to call the function with invoke. But this time
it didn't work because GetTickCount() doesn't use parameters. So I tried "call".
FASM compiled but when I run my compiled program, it seems to crash at
the point where I call GetTickCount().
What could be the reason?

And there's another thing: I asked about already but didn't get a real answer.
I tried to learn it on my own but I still understand nearly NOTHING about
this calling-conventions! I know there's a C-Calling-Convention and I know
how it gets used (push params in reversed order and call), but what about
other calling conventions? Why do they exist and when do they get used (
I heared about PASCAL calls and so on)?
What convention is used when I use "call" or "stdcall"? Or invoke?? Is invoke
the same as call and stdcall? Cinvoke is C-Call I think?

PLEASE HELP ME Sad

06 Jan 2005, 16:40

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia

vid 06 Jan 2005, 20:16

why "call", just use "invoke GetTickCount" without any arugments and it should work. Anyway, you can call it youself by "call [GetTickCount]" (because "invoke something" is "call [something]", that's why it crashed)

06 Jan 2005, 20:16

denial

Joined: 12 Sep 2004
Posts: 98

denial 06 Jan 2005, 20:28

No Invoke GetTickCount doesn't work! But call [GetTickCount] did work! But I don't understand something: When I write an own function with proc/endp, I have to call it through "call Progname" and not "call [Progname]"... oO What's the matter?

And please help me with my other questions... I really need to know it.
Thank you.

06 Jan 2005, 20:28

msmith

Joined: 22 Jun 2003
Posts: 40
Location: Missouri

msmith 06 Jan 2005, 23:15

Here is a copy/paste from my program. This code works fine every day.

Code:

invoke GetTickCount
mov [_Tmp1],eax

Here are 2 C style calls which work fine also.

Code:

cinvoke ltoa,eax,[_ConvBuf1],10
...
cinvoke system,[_IOBuffer]

06 Jan 2005, 23:15

HarryTuttle

Joined: 26 Sep 2003
Posts: 211
Location: Poland

HarryTuttle 06 Jan 2005, 23:18

because if you call an import then

invoke addr makes call [addr]
the import is just pointer to exported function; addr= pointer to dll

if you make function ,it has own address not pointer to the address so you call addr
addr = proc

if you type invoke it means for example call [00041000]
and data placed under this address can jumps to the forbidden addres which has no access to execute.

every is clear?

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06 Jan 2005, 23:18

msmith

Joined: 22 Jun 2003
Posts: 40
Location: Missouri

msmith 06 Jan 2005, 23:21

BTW, here is the cinvoke stuff I used in the previous post.

Code:

;declares a cdecl procedure
macro cproc name,[params]
{
   common
      name:
   push ebp
    mov ebp, esp            
    
    virtual at ebp +8                 

      if ~ params eq    
          forward
                     local ..params          
                    ..params dd ?
                       params equ ..params
         common
      end if
      end virtual
 local ..dynamic_data,..dynamic_size
 dynamic_data equ ..dynamic_data
     dynamic_size equ ..dynamic_size
     virtual at ebp - dynamic_size
       dynamic_data:
}

macro center
{       
            dynamic_size = $ - dynamic_data
   end virtual
   sub esp,dynamic_size
}

macro cret
{      
    add esp,dynamic_size
        pop ebp
     ret     
}

;calling/ invoking a cdecl procedure

macro ccall proc,[arg]            ; call cdecl procedure
{ 
   common
              local ..param_num 
          ..param_num=0           
    reverse
             push arg
            ..param_num = ..param_num + 4           
    common
              call proc 
          add esp, ..param_num            
}

macro cinvoke proc,[arg]              ; invoke cdecl procedure (indirect)
{
       common
              if ~ arg eq
                         ccall [proc],arg
            else
                        call [proc]
 end if 
}

06 Jan 2005, 23:21

denial

Joined: 12 Sep 2004
Posts: 98

denial 07 Jan 2005, 11:26

Thank you for all your answers. Except the calling-conventions, everything is clear now. However, "invoke GetTickCount" I can't use because FASM gives me errors. I'm confused about. But however, I can use call and understand the system now.

Thank you very much. And if someone knows about calling-conventions, I would be glad for a further answer.

07 Jan 2005, 11:26

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