Label inside of repeat block?

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AlexP

Joined: 14 Nov 2007
Posts: 561
Location: Out the window. Yes, that one.

AlexP 02 Mar 2008, 18:39

I'm not allowed to use generic labels (or any labels at all!) inside of a repeat block, is there any way around it?

Code:

repeat 4
@@: ; "symbol already defined" error
end repeat

02 Mar 2008, 18:39

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20761
Location: In your JS exploiting you and your system

revolution 03 Mar 2008, 00:39

Code:

rept 4 {
@@: ; No more "symbol already defined" error
}

03 Mar 2008, 00:39

AlexP

Joined: 14 Nov 2007
Posts: 561
Location: Out the window. Yes, that one.

AlexP 03 Mar 2008, 01:08

Thank You! (probably one of the simplest question-response's I've seen)

03 Mar 2008, 01:08

AlexP

Joined: 14 Nov 2007
Posts: 561
Location: Out the window. Yes, that one.

AlexP 03 Mar 2008, 01:55

Okay, I'm having troubles with the rept {} macro. I looked over fasm doc's for it, and it looks like it should work in my code, but now I get an error I've never seen before, "Incomplete Macro". Here's the full code I use:

Code:

macro MixColumns state { ; 46*4 instructions

 rept 4 counter
  {
    mov eax,dword[array_r]
    mov dword[array_a],eax
    shl al,1
    mov     [array_b + 0],al
    jnc @f                         
    xor byte[array_b + 0],GF_modulus
@@: shl ah,1                       
    mov     [array_b + 1],ah
    jnc @f                         
    xor byte[array_b + 1],GF_modulus
@@: shr eax,16                     
    shl al,1                       
    mov     [array_b + 2],al
    jnc @f                         
    xor byte[array_b + 2],GF_modulus
@@: shl ah,1                       
    mov     [array_b + 3],ah
    jnc @f                         
    xor byte[array_b + 3],GF_modulus
@@: mov al,[array_b + 0]
    xor al,[array_a + 3]
    xor al,[array_a + 2]
    xor al,[array_b + 1]
    xor al,[array_a + 1]
    mov    [dest + 0],al
    mov al,[array_b + 1]
    xor al,[array_a + 0]
    xor al,[array_a + 3]
    xor al,[array_b + 2]
    xor al,[array_a + 2]
    mov    [dest + 1],al
    mov al,[array_b + 2]
    xor al,[array_a + 1]
    xor al,[array_a + 0]
    xor al,[array_b + 3]
    xor al,[array_a + 3]
    mov    [dest + 2],al
    mov al,[array_b + 3]
    xor al,[array_a + 2]
    xor al,[array_a + 1]
    xor al,[array_b + 0]
    xor al,[array_a + 0]
    mov    [dest + 3],al
  }
}

the three array's and the dest array are here, using the counter var:

Code:

; procedure constants

array_a = Log   + ((counter-1)*4)
array_b = Alog  + ((counter-1)*4)
array_r = Temp  + ((counter-1)*4)
dest    = State + ((counter-1)*4)

It is part of some other things with GF that I've been experimenting with, but the "incomplete macro" error has me baffled. Until I find out what's wrong, I'll go back to looping for now.

03 Mar 2008, 01:55

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20761
Location: In your JS exploiting you and your system

revolution 03 Mar 2008, 02:01

Code:

macro MixColumns state {
 rept 4 counter
  \{
.....
  \}
}

03 Mar 2008, 02:01

AlexP

Joined: 14 Nov 2007
Posts: 561
Location: Out the window. Yes, that one.

AlexP 03 Mar 2008, 02:21

"Undefined symbol counter"
It now does not recognize the counter symbol, the array symbols are working right (changed to "equ" instead of "=").

03 Mar 2008, 02:21

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 20761
Location: In your JS exploiting you and your system

revolution 03 Mar 2008, 02:25

You have to define your "array_x" variables inside the rept structure. Use "=" not "equ".

Code:

macro MixColumns state {
 rept 4 counter
  \{
    array_a = Log   + ((counter-1)*4)
...

03 Mar 2008, 02:25

AlexP

Joined: 14 Nov 2007
Posts: 561
Location: Out the window. Yes, that one.

AlexP 03 Mar 2008, 02:31

Works:

Code:

macro MixColumns state {
    rept 4 counter 
    \{
       ; constants
       ...
    \}
}

< Thanks again >

03 Mar 2008, 02:31

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