Invalid Number Help

[lurner]

Hello, I am trying to run a simple ASM sample that opens notepad.exe. When I try to load WinExec and ExitProcess addresses into bx the TASM assembler says:

Assembling file: test.ASM
**Error** test.ASM(29) Illegal number
**Error** test.ASM(34) Illegal number
Error messages: 2
Warning messages: None
Passes: 1
Remaining memory: 418k

Here is my code... btw: I am writing for 8086, Windows XP

.model small
.stack
.data

.code

main proc		;start main procEDURE


start:

jmp short GetCommand

CommandReturn:
    	 pop bx            	;bx now holds the handle to the string
   	 xor ax,ax
   	 push ax
    	 xor ax,ax
  	 mov [bx + 22],al   	;insert the NULL character
  	 push bx
  	 mov bx, 0x77e6fd35
  	 call bx           	;call WinExec(path,showcode)

   	 xor ax,ax        	;zero the register again, clears winexec retval
   	 push ax
   	 mov bx, 0x77e798fd
 	 call bx           	;call ExitProcess(0);


GetCommand:
    	call CommandReturn
	db "cmd.exe /c notepad.exe$"
   mov 	ax,4c00h		;end clean
   int 	21h			;intERRUPT - (DOS Service)
main endp			;end main procEDURE
end main			;exit application

I must be trying to load the addresses wrong or I am not doing something with them in order to make them valid. I tried using quotes "" and square brackets [] and neither worked. Can someone please help me fix this code so it will work. This will be a great snippet to learn from if I can just get it to movE the kernel addresses into bx. Unless there is a better way, in which I would be interested in seeing.

Thanks in advance

[japheth]

the error comes from line

> mov bx, 0x77e6fd35

it is in C syntax, not ASM, and bx is a 16 bit register, it cannot hold 32bit values.

Furthermore, you are trying to call 32bit protected mode code from 16 bit real-mode (or v86mode) code. That cannot work.

[NoHero]

Originally Posted by japheth

the error comes from line

> mov bx, 0x77e6fd35

it is in C syntax, not ASM, and bx is a 16 bit register, it cannot hold 32bit values.

Furthermore, you are trying to call 32bit protected mode code from 16 bit real-mode (or v86mode) code. That cannot work.

That's absolutly correct. Try this instead:

mov ebx, 077e798fdh

The WinAPI calls are far calls so you will need a 32bit register and a valid 32bit windows compiler such as the Microsoft Macro Assembler (MASM) or the Netwide Assembler for Win32. And as far as I know they are named like __imp__ExitProcess() or something like that. .

/ 11 posts to go

[Lican]

When I was using tasm while writing code I used a macro:

calle MACRO x
extrn x:PROC
call x
ENDM calle

then I just wrote:

calle somefunction

and that was enough. I also recommend to read some optimization trick, because they can be quite useful when writing in asm. I learned then by heart and now with c++ I'm still trying to use them, although the compiler's optimizer will "do that for me" it's just a habit :P

[lurner]

oh.. ok so use nasm or masm and try it that way.. I am learning ASM in reverse I first learnt VB then C++ and now ASM. I am so use to API to not use it makes me feel limited while coding, I am definently graduating early to 32bit as soon as possible.

thanks a lot for your help guys, much appreciated.