Importing C functions to FASM

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shaolin007

Joined: 03 Sep 2004
Posts: 65

shaolin007 06 Jun 2005, 19:43

Anyone give me a hand here? What am I missing or doing wrong? Thanks

Code:

format PE GUI 4.0
entry BeginCode

include '%fasminc%\win32a.inc'

section '.code' executable readable writeable

BeginCode:
          push ebp
          mov ebp, esp
          push hellostring
          call [printf]
          pop ebp
          ret 4
          push ebp
          mov ebp, esp
          call [getch]
          pop ebp
          push 0
          call [ExitProcess]



section '.data' data readable writeable

hellostring             db "This was printed out with the printf() function!",0

section '.idata' import data readable writeable

  library kernel,'KERNEL32.DLL',\
          msvcrt,'MSVCRT.DLL'

  import kernel,\
         ExitProcess,'ExitProcess'

06 Jun 2005, 19:43

flaith

Joined: 07 Feb 2005
Posts: 122
Location: $300:20 58 FC 60 N 300G => Vietnam

flaith 06 Jun 2005, 20:15

first you must define

Code:

  extrn printf                   ; because of c

and you must compile it as an objet

Code:

format MS COFF

and link with gcc !!!
hmmm May be !

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06 Jun 2005, 20:15

coconut

Joined: 02 Apr 2004
Posts: 326
Location: US

coconut 07 Jun 2005, 04:32

hello, http://board.flatassembler.net/topic.php?t=3195

07 Jun 2005, 04:32

shaolin007

Joined: 03 Sep 2004
Posts: 65

shaolin007 07 Jun 2005, 12:19

Thanks coconut, but I'm still having problems getting this to run. It crashes at run time. I'm I still doing something wrong?

Code:

format PE CONSOLE 4.0
entry BeginCode

include '%fasminc%\win32a.inc'

section '.code' executable readable writeable

BeginCode:
          cinvoke printf, hellostring
          cinvoke getch
          push 0
          call [ExitProcess]



section '.data' data readable writeable

hellostring             db "This was printed out with the printf() function!",0

section '.idata' data readable writable

  library kernel,'KERNEL32.DLL',\
          msvcrt,'msvcrt.dll'

  import kernel,\
         ExitProcess,'ExitProcess'

  import msvcrt,\
         printf,'printf',\
         getch, 'getch'

07 Jun 2005, 12:19

pelaillo
Missing in inaction

Joined: 19 Jun 2003
Posts: 878
Location: Colombia

pelaillo 07 Jun 2005, 13:25

You are missing first parameter to printf:

Code:

          cinvoke printf, format, hellostring 
(...)
format db "%s",0
hellostring             db "This was printed out with the printf() function!",0

07 Jun 2005, 13:25

shaolin007

Joined: 03 Sep 2004
Posts: 65

shaolin007 07 Jun 2005, 13:59

pelaillo wrote:

You are missing first parameter to printf:

Code:

          cinvoke printf, format, hellostring 
(...)
format db "%s",0
hellostring             db "This was printed out with the printf() function!",0

I still can't get it to work. By the way, if you don't specify a format type then couldn't you just pass the pointer to the string like you do in C?

Code:

example

printf("My string"); // No argument type string

new code

Code:

format PE CONSOLE 4.0
entry BeginCode

include '%fasminc%\win32a.inc'

section '.code' executable readable writeable

BeginCode:

          cinvoke printf, type, hellostring
          cinvoke getch

          push 0
          call [ExitProcess]



section '.data' data readable writeable

type                    db "%s",0
hellostring             db "This was printed out with the printf() function!",0

section '.idata' data readable writable

  library kernel,'KERNEL32.DLL',\
          msvcrt,'msvcrt.dll'

  import kernel,\
         ExitProcess,'ExitProcess'

  import msvcrt,\
         printf,'printf',\
         getch, 'getch'

07 Jun 2005, 13:59

Reverend

Joined: 24 Aug 2004
Posts: 408
Location: Poland

Reverend 07 Jun 2005, 14:22

Maybe your 'cinvoke' macro is incorrect. Try:

Code:

    push    hellostring
    call    [printf]
    add     esp, 4
    call    [getch]

07 Jun 2005, 14:22

shaolin007

Joined: 03 Sep 2004
Posts: 65

shaolin007 07 Jun 2005, 14:35

Reverend wrote:

Maybe your 'cinvoke' macro is incorrect. Try:

Code:

    push    hellostring
    call    [printf]
    add     esp, 4
    call    [getch]

Thanks man but still no dice. Sad

There must be something I am missing. Seems like I read somewhere that you have to underscore the name of the functions but I have tried that and it still didn't work.

07 Jun 2005, 14:35

flaith

Joined: 07 Feb 2005
Posts: 122
Location: $300:20 58 FC 60 N 300G => Vietnam

flaith 07 Jun 2005, 17:06

Much better now (look at the 'idata' section and 'getch' to '_getch')

Code:

format PE CONSOLE 4.0
entry BeginCode

include '%fasminc%\win32a.inc'

section '.code' executable readable writeable

BeginCode:

          cinvoke printf, type, hellostring
          cinvoke getch

          invoke ExitProcess


section '.data' data readable writeable
type                    db "%s",0
hellostring             db "This was printed out with the printf() function!",0

section '.idata' import data readable writable

  library kernel,'KERNEL32.DLL',\
          msvcrt,'msvcrt.dll'

  import kernel,\
         ExitProcess,'ExitProcess'

  import msvcrt,\
         printf,'printf',\
         getch, '_getch'

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07 Jun 2005, 17:06

shaolin007

Joined: 03 Sep 2004
Posts: 65

shaolin007 07 Jun 2005, 18:27

flaith wrote:

Much better now (look at the 'idata' section and 'getch' to '_getch

Hmm still crashing. I wouldn't think that it would be like this to call a simple c function.

07 Jun 2005, 18:27

flaith

Joined: 07 Feb 2005
Posts: 122
Location: $300:20 58 FC 60 N 300G => Vietnam

flaith 07 Jun 2005, 18:42

I don't get it, it run ok for me :

compiled with Fasm 1.61.8

_________________
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07 Jun 2005, 18:42

shaolin007

Joined: 03 Sep 2004
Posts: 65

shaolin007 07 Jun 2005, 19:22

I don't get it either. I have exactly the same code as you have there and it will compile fine but when you execute it it crashes! Doesn't make a bit of sense. Any suggest as to what it may be?

07 Jun 2005, 19:22

flaith

Joined: 07 Feb 2005
Posts: 122
Location: $300:20 58 FC 60 N 300G => Vietnam

flaith 07 Jun 2005, 20:40

Ok, and if you try my own exe ???

Download ZIP

_________________
Je suis sur de 'rien', mais je ne suis pas sur du 'tout'.

07 Jun 2005, 20:40

coconut

Joined: 02 Apr 2004
Posts: 326
Location: US

coconut 07 Jun 2005, 21:38

what windows are you running, and msvcrt.dll version? btw looking at msvcrt with dependancy walker (great free program), getch is exported as _getch

http://www.dependencywalker.com/

Last edited by coconut on 07 Jun 2005, 21:42; edited 1 time in total

07 Jun 2005, 21:38

shaolin007

Joined: 03 Sep 2004
Posts: 65

shaolin007 07 Jun 2005, 21:39

flaith wrote:

Ok, and if you try my own exe ???

Download ZIP

LOL I know what it is now. I forgot to add the 'import' directive to my '.idata' section! Silly error! Laughing

07 Jun 2005, 21:39

coconut

Joined: 02 Apr 2004
Posts: 326
Location: US

coconut 07 Jun 2005, 21:40

ouch lol

07 Jun 2005, 21:40

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