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james



Joined: 07 Sep 2005
Posts: 45
Location: Australia
I hope this isnt too silly a question but is there a way to get the address if a label ?

eg:

Code:
    mytable DW label1, label2, label3

    label1:
        some code here

    label2: 
        some code here

    


ie: mytable is now an array of addresses i can JMP to

rgs, James.
Post 09 Nov 2005, 06:02
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 16652
Location: In your JS exploiting you and your system
Code:
    label1: 
        some code here 

 mov eax, label1 ;get address of label1
 mov eax, [label1] ;get contents of address of label1     
Is that what you were thinking of?
Post 09 Nov 2005, 07:20
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Matrix



Joined: 04 Sep 2004
Posts: 1171
Location: Overflow
i recently made some advanced menu functions that contain the data in an array type, is that what you mean?

Code:
mov si, arraytype01
call menu

...
ret

arraytype01:
db "Proc1"
dw proc1_addr
db 0
db " proc2"
dw proc2_addr
dw 0
    
Post 09 Nov 2005, 09:44
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7108
Location: Slovakia
term "address of label" isn't very good. It's problem coming from stupid MASM syntax. In FASM (and it's also logical too) label is "placeholder for address", so if label "a" is "at address 401122h", then writing "a" should mean same thing as writing "401122h". so
Code:
mov eax,a ;mov eax, 401122h
mov eax,[a] ;mov eax [401122h]
b = 3*a + 5 ;b = 3*401122h + 5    


PS: Internally it's a little bit more complicated because of some special cases...
Post 09 Nov 2005, 09:47
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james



Joined: 07 Sep 2005
Posts: 45
Location: Australia
Thankyou all for the replies. However,

Matrix, your example is good but I need the address represented by a label not the address of a function.

Vid, given your description of using label 'a' like the following:

Code:
a:
;
mov eax, a    ;   eax now has address of where 'a' is.
    


then defining data like below would also work ?

Code:
addressOfALabel dw a
    


Yes ?

Rgs, James.
Post 09 Nov 2005, 20:43
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7108
Location: Slovakia
yes, right
Post 09 Nov 2005, 20:46
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james



Joined: 07 Sep 2005
Posts: 45
Location: Australia
Vid,

When I try to define storage like this:
Code:
section '.data' data readable writeable

labelTest dw labelHere
    


I get the following error:
Code:
labelTest dw labelHere
error: invalid use of symbol.
flat assembler  version 1.64
3 passes, 1536 bytes.
    


Can you please provide an example of defining a variable that contains the address of where a label is ?

Rgs, James

ps - thanks for the super quick responses.
Post 09 Nov 2005, 20:54
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 16652
Location: In your JS exploiting you and your system
Code:
section '.data' data readable writeable 

labelTest dd labelHere ;<-- use DD for 32 bit addresses    
Post 10 Nov 2005, 00:49
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Matrix



Joined: 04 Sep 2004
Posts: 1171
Location: Overflow
james wrote:
Thankyou all for the replies. However,

Matrix, your example is good but I need the address represented by a label not the address of a function.

Vid, given your description of using label 'a' like the following:

Code:
a:
;
mov eax, a    ;   eax now has address of where 'a' is.
    


then defining data like below would also work ?

Code:
addressOfALabel dw a
    


Yes ?

Rgs, James.


James,
and the answer to the thread question is yes.
i managed this structure a few months before, but its a work to index those labels, it is better i think to make a structure, though fairly more advanced.

i think you did not understand what i was trying to write, a label has an address and a function has an address also, i have program in progress that writes the function addresses in memory during run time, depends on far call table, near call table is used, it is possible

ok i send code:
more will be downloadable soon at my web site - at assemmbly section (free)

Code:
macro settextcolor _reg,_rf,_gf,_bf,_lf,_rb,_gb,_bb,_lb ; byte register fore:RGBL Back:RGBL
{
light=1000b
red=100b
green=10b
blue=1
back=(_lb shl 3)+(_rb shl 2)+(_gb shl 1)+(_bb)
fore=(_lf shl 3)+(_rf shl 2)+(_gf shl 1)+(_bf)
_color=fore+(back shl 4)
;wordcolor=color shl 8
;dwordcolor=(wordcolor shl 16) or wordcolor
 mov _reg,_color and $ff}

macro dbtextcolor _rf,_gf,_bf,_lf,_rb,_gb,_bb,_lb ; byte register fore:RGBL Back:RGBL
{
light=1000b
red=100b
green=10b
blue=1
back=(_lb shl 3)+(_rb shl 2)+(_gb shl 1)+(_bb)
fore=(_lf shl 3)+(_rf shl 2)+(_gf shl 1)+(_bf)
_color=fore+(back shl 4)
;wordcolor=color shl 8
;dwordcolor=(wordcolor shl 16) or wordcolor
db _color and $ff}

macro bdisplay _stringpointer001
{ mov si, _stringpointer001
  call bwritestring }
k_up=  $48e0
k_down=$50e0
k_esc= $011b
k_enter=$1c0d
menuxypos=$0505

org 256

mov ax,$03
int 10h

mov bx,MainMenuDataBlockPointer
call DrawZMenu01

int 20h ; exit

DrawZMenu01: ; draw menu from zmenu01 structure from ds:bx
push es
push $b800
pop es
mainloop:
and ebx,$ffff
.resetdrawmenu:
mov si,[bx]             ;data start
xor edx,edx             ;current element

or word [bx+7],0 ; cached proc address
jz exit_proc.notread
;.readthekey:
call breadkey  ;returns: AH = BIOS scan code AL = ASCII character note: enhanced
cmp ax,k_enter
jne .not_enter
pop es
pusha
call word [bx+7] ; cached proc address
popa
push es
push $b800
pop es
and word [bx+7],0 ; cached proc address
jmp mainloop.resetdrawmenu
.not_enter:
and word [bx+7],0 ; cached proc address
cmp ax,k_up
jne .not_up
or byte [bx+6],0 ; choicepointer
jz .notdec
dec byte [bx+6] ; choicepointer
.notdec:
jmp mainloop.resetdrawmenu
.not_up:
cmp ax,k_down
jne .not_down
inc byte [bx+6] ; choicepointer
jmp mainloop.resetdrawmenu
.not_down:
cmp ax,k_esc
jne mainloop.resetdrawmenu
pusha
push ax
exit_proc:
pop ax
popa
pop es
ret
.notread:

.drawmenu:

mov cx,[bx+4]          ;cl=normal color, ch=highlight color
mov al,byte [bx+6]     ;choicepointer
cmp al,dl
jne .no_highlight
rol cx,8
.no_highlight:

push ax bx dx
mov bx,[bx+2]
add bh,dl
call writestring80x25 ; DS:SI = address of string bl=x bh=y ch=color , 0 terminated string !
jmp .dontskip
.skipelement:
.loop:lodsb
or al,al
jnz .loop
.dontskip:
pop dx bx ax
cmp dl,al
jne .notselected
lodsw ; proc address in ax
mov [bx+7],ax
jmp .selected
.notselected:
lodsw ; proc address in ax
.selected:
inc dx

or byte [si],0 ; last element
jnz .notoveryet
dec dl
cmp [bx+6],dl
jnae .ok
mov [bx+6],dl
.ok:
jmp mainloop.resetdrawmenu;.readthekey
.notoveryet:
jmp  exit_proc.drawmenu


MainMenuDataBlockPointer:
dw .begindatatablock
.menuxypos:     db 24,7 ; from top left, x,y ; +2 (word)
.normalattr:    dbtextcolor 1,1,1,0,0,1,0,0 ; byte register fore:RGBL Back:RGBL ; +4 (word)
.highlight:     dbtextcolor 0,1,0,0,0,0,0,0 ; byte register fore:RGBL Back:RGBL
.choicepointer: db 0 ; choicepointer              ; +6 (byte)
.selectedprocaddress: dw 0 ; proc address offset  ; +7 (word)

.begindatatablock:
db 'Erase & Program, then Lock',0
dw erase_program_lock
db 'Erase & Program Only',0
dw erase_program
db 'Program',0
dw program
db 'Chip Erase',0
dw chiperase
db 'Lock',0
dw _lock
db 'Communication Speed Test',0
dw spdtest
db 'EXIT',0
dw exit_proc
db 0

breadkey:  ;returns: AH = BIOS scan code AL = ASCII character note: enhanced
mov ah,$10
int $16
ret

bgotoxy: ; dl=x, dh=y ( 0,0 = upper left ) RETURNS:  AX,BX,DX = undefined.
push ax dx ; transparency
mov ah,2
xor bh,bh
int 10h
pop dx ax
ret

bwritestring: ; Writes a 0 terminated string to screen ( string is at ds:si )
push ax bx
mov bx,7 ; use video page 0, normal white
mov ah,$e
.localloop:lodsb
           or al,al
           jnz .next_char
           pop bx ax
           ret
.next_char:int 10h
           jmp .localloop

writestring80x25: ; DS:SI = address of string bl=x bh=y ch=color , 0 terminated string !
xor ax,ax
xchg al,bh
mov di,ax
shl di,2
add di,ax
shl di,4
add di,bx
shl di,1

.again:
mov ah,ch
lodsb
or al,al
jz .ext2
stosw
jmp .again
.ext2:
ret

highlightbackground: ; eax = dword color
xor di,di
mov cx,1000
.setback:
and dword [es:di],$00ff00ff
or dword [es:di],eax
add di,4
loop .setback
ret

bwritedword: ; EAX = number, BL = base
  push eax ebx ecx edx
  and ebx,$ff
  cmp bl,2 ; base can't be less than 2 Smile
  jge .start
  mov bl,10     ; using bx = 10 instead
  .start:
  xor ecx,ecx     ; cx = 0
  .new:
  xor edx,edx     ; dx = 0
  div ebx        ; number / base
  push dx       ; push the remainder
  inc ecx        ; increase the "digit-count"
  or eax,eax      ; if the quotient still is not 0, do it once more
  jnz .new
  .loop:
  pop ax        ; pop the remainder
cmp al,10
sbb al,69h
das
mov ah,$e
int 10h
  loop .loop
  pop edx ecx ebx eax
ret

cls80x25t: ; clear the text screen really fast
xor eax,eax
mov di,ax
mov eax,$07200720
mov cx,1000
rep stosd
ret

spdtest:
call display_currentproc
ret
_lock:
call display_currentproc
ret
chiperase:
call display_currentproc
ret
program:
call display_currentproc
ret
erase_program:
call display_currentproc
ret
erase_program_lock:
call display_currentproc
ret

display_currentproc:
movzx eax,byte [bx+6]
mov bl,10
call bwritedword ; EAX = number, BL = base
ret
    
Post 10 Nov 2005, 01:02
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7108
Location: Slovakia
james: apps in win32 are usually (well, always) loaded above 10000h, so it won't fit in dword. sorry, i missed that. it's little like if you was trying to compile "something dw 401A2Bh", it can't fit. Labels are 32bit so use DD as revolution said. Another problem is that in win32 they aren't really constant, so you can't sometimes use them in that manner, but for now better don't care about that oo much.
Post 10 Nov 2005, 01:42
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james



Joined: 07 Sep 2005
Posts: 45
Location: Australia
Oh boy !!

I can't believe I used DW instead of DD. Im feeling very stupid right now as I do know better. Embarassed

Changing to the right size worked.

Thanks for your patience.

Rgs, James.
Post 10 Nov 2005, 01:46
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7108
Location: Slovakia
we were all starting.... (but we didn't have internet)
Post 10 Nov 2005, 02:00
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