The right way to declare two dimensional array :/

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Szustarol

Joined: 11 Jul 2016
Posts: 9

Szustarol 11 Jul 2016, 08:47

Hi!
I have searched whole internet and found 2 ways of declaring 2d arrays:
(i want to declare array of the size of default windows console)
areatodraw TIMES 25*80 db 0x00
or
areatodraw db 25 dup(80 dup(0x00))
none seems to work when i try to draw end of line character to the last char
in row
i calculate the adress like this- (row-1)*lenghtofrow+positioninrow
mov areatodraw[0x50], 0x8A

im not sure why it isint working maybe i move the value wrong way, can anyone help?

11 Jul 2016, 08:47

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20459
Location: In your JS exploiting you and your system

revolution 11 Jul 2016, 09:02

Show your code.

11 Jul 2016, 09:02

Szustarol

Joined: 11 Jul 2016
Posts: 9

Szustarol 11 Jul 2016, 09:21

Code:

format PE console
entry start 
include 'include/win32a.inc' 

section '.text' code executable
        start:

        stlp:
              push 200
              call [Sleep]
              add esp, 0x04
              call CHECKFORCHAR
              push EAX
              push intbuff
              call [printf]
              add esp, 0x08
              push space
              push strbuff
              call [printf]
              add esp, 0x08
              jmp stlp
              koniec:
              push 0
              call [ExitProcess]
        CHECKFORCHAR:
                push ebp
                call [_kbhit]
                cmp EAX, 0
                je nopress
                call [_getch]
                cmp EAX, 0xE0
                jne nopress
                call [_getch]
                nopress:
                pop ebp
                ret
        FILLAREA:
                push ebp
                mov ebx, areatodraw[0x50]
                mov ebx, 0x8A
                pop ebp
                ret

section '.data' data readable writeable
        intbuff db '%d', 0
        strbuff db '%s', 0
        space db ' ', 0
        areatodraw db 25 dup(80 dup(0x00))
section '.idata' data readable import 
        library kernel32, 'kernel32.dll', msvcrt, 'msvcrt.dll'
        import kernel32, ExitProcess, 'ExitProcess', Sleep, 'Sleep', GetModuleHandle,'GetModuleHandleA'
        import msvcrt, scanf, 'scanf', printf, 'printf', _kbhit, '_kbhit', _getch, '_getch'

i get the "Extra characters on line" error when array element is moved to ebx

Also another question does the windows Sleep function remove its parameter from stack automatically? I noticed if i add 0x04 to esp after calling sleep after some time program crashes when it reaches bottom of the stack, when i dont do this program runs just fine

11 Jul 2016, 09:21

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20459
Location: In your JS exploiting you and your system

revolution 11 Jul 2016, 10:27

"areatodraw" is just a pointer. You can access bytes by simple addition:

Code:

mov ebx, areatodraw + 0x50 ;offset 0x50 bytes

Szustarol wrote:

Also another question does the windows Sleep function remove its parameter from stack automatically? I noticed if i add 0x04 to esp after calling sleep after some time program crashes when it reaches bottom of the stack, when i dont do this program runs just fine

All Windows API calls (except for WSPRINTF) use STDCALL convention, so you should normally have no need to manually adjust ESP after calling.

11 Jul 2016, 10:27

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