FillConsoleOutputCharacter doesn't work with a COORD struct

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vanzan

Joined: 27 Apr 2010
Posts: 14

vanzan 27 Apr 2010, 21:00

Hello !

I've got a problem with the FillConsoleOutputCharacter function

When I use a structure COORD in oder to fix the start cell, it doesn't work,.... nothin apear

The only on way which workin is to put "0"/"NULL" instead of the COORD struct,....but I loose the positionning of the string Crying or Very sad

, which is the main interressant feature of this fonction ^^

This is the code which doesn't work...:

Code:

format PE console 4.0 
entry start 

include '%fasminc%/win32ax.inc' 

section '.data' data readable writeable 

hCSB      dd ? 
Temp    dd ? 
     struc COORD{ 
                .X dw ?       
              .Y dw ?     
               } 
          
          testt COORD


section '.code' code readable executable 
start:    
    invoke  CreateConsoleScreenBuffer,GENERIC_WRITE,0,0,1,0 
     mov     [hCSB],eax 
  inc     eax 
 jz      exit            ;if eax=-1 error 
    invoke  SetConsoleActiveScreenBuffer,[hCSB] 
          
mov [testt.X],52
mov [testt.Y],10
                    
          
    invoke  FillConsoleOutputCharacter,\ 
               [hCSB],80,\ 
             80,testt,Temp 

    invoke  Sleep,4000 
  invoke  CloseHandle,[hCSB] 
exit:  
    invoke  ExitProcess,0 


                
;include 'csb.imp' 
section '.idata' import data readable writeable 

  library kernel32,'kernel32.dll' 

  import kernel32,\ 
         CloseHandle,'CloseHandle',\ 
         CreateConsoleScreenBuffer,'CreateConsoleScreenBuffer',\ 
         ExitProcess,'ExitProcess',\ 
         FillConsoleOutputCharacter,'FillConsoleOutputCharacterA',\ 
         SetConsoleActiveScreenBuffer,'SetConsoleActiveScreenBuffer',\ 
         Sleep,'Sleep'

27 Apr 2010, 21:00

Picnic

Joined: 05 May 2007
Posts: 1403
Location: Piraeus, Greece

Picnic 27 Apr 2010, 23:19

hi vanzan, try this:

Code:

    invoke  FillConsoleOutputCharacter,\ 
               [hCSB],80,\ 
             80,DWORD[testt],Temp

27 Apr 2010, 23:19

vanzan

Joined: 27 Apr 2010
Posts: 14

vanzan 28 Apr 2010, 05:33

Thank you very, very much ! Smile

How can I know when I had to precise the type of data ?

28 Apr 2010, 05:33

revolution
When all else fails, read the source

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

revolution 28 Apr 2010, 05:55

vanzan wrote:

How can I know when I had to precise the type of data ?

When you read the C-code structure in the API docs you look for the prefix 'lp'.

Code:

BOOL FillConsoleOutputCharacter(

    HANDLE hConsoleOutput,    // handle to screen buffer 
    TCHAR cCharacter,    // character to write 
    DWORD nLength,    // number of character cells to write to 
    COORD dwWriteCoord,    // x- and y-coordinates of first cell 
    LPDWORD lpNumberOfCharsWritten    // pointer to number of cells written to 
);

Notice that dwWriteCoord does not have the 'lp' prefix so it is not a pointer, it is a value with the size 'dw'.

28 Apr 2010, 05:55

baldr

Joined: 19 Mar 2008
Posts: 1651

baldr 28 Apr 2010, 05:59

vanzan,

When structure is passed by value (i.e. argument type is not a pointer) as function argument, you have to copy it to stack entirely.

28 Apr 2010, 05:59

vanzan

Joined: 27 Apr 2010
Posts: 14

vanzan 29 Apr 2010, 10:30

Ok ! Thank You very much for the explanation Wink

I think I've understood the principle =)

PS: I'm creating an ASCII Arkanoid for my IT Shcool ASM project

29 Apr 2010, 10:30

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