Obfuscated Code Contest
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Obfuscated Code Contest
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WikiGuru
ADOS (Attention deficit... Oh! Shiny!)


Elite


Joined: 15 Sep 2005
Posts: 923
Posted: 10 Jan 2009 02:24:04 pm    Post subject:
What's the most obfuscated code you can come with in z80 that performs a simple task (draw 8*8 sprite, do some simple arithmetic, etc.)?

Edit:
One rule, it must be able to run NoStub.

Last edited by Guest on 10 Jan 2009 02:24:55 pm; edited 1 time in total
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calc84maniac


Elite


Joined: 22 Jan 2007
Posts: 770
Posted: 10 Jan 2009 03:30:08 pm    Post subject:
A = B + C

Code:
ld a,b
and c
add a,a
ld d,a
ld a,b
xor c
add a,d


Should work. Razz

Last edited by Guest on 10 Jan 2009 03:47:29 pm; edited 1 time in total
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darkstone knight


Advanced Member


Joined: 07 Sep 2008
Posts: 438
Posted: 10 Jan 2009 03:38:27 pm    Post subject:
A=B+C

LD A,B
AND C
or A\ RL A
LD B,A
XOR C
ADD A,B

yes, this does actualy work Dry
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calc84maniac


Elite


Joined: 22 Jan 2007
Posts: 770
Posted: 10 Jan 2009 03:42:12 pm    Post subject:
darkstone knight wrote:
A=B+C

LD A,B
AND C
or A\ RL A
LD B,A
XOR C
ADD A,B

yes, this does actualy work Dry

No it doesn't. Razz Try with B=1 and C=0.
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darkstone knight


Advanced Member


Joined: 07 Sep 2008
Posts: 438
Posted: 10 Jan 2009 03:45:39 pm    Post subject:
LD A,B
AND C
or A\ RL A
LD H,A
LD A,B
XOR C
ADD A,H

minor correction >.>

(btw, this is how adding 2 numbers whit logic switches work.. kinda)
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WikiGuru
ADOS (Attention deficit... Oh! Shiny!)


Elite


Joined: 15 Sep 2005
Posts: 923
Posted: 11 Jan 2009 04:26:56 pm    Post subject:
A = -C


Code:
 or $FF
 xor c
 inc a
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elfprince13
Retired


Super Elite (Last Title)


Joined: 11 Apr 2005
Posts: 3500
Posted: 12 Jan 2009 11:44:44 am    Post subject:
*I* think it would be more fun to try and obfuscate TI-Basic and make people guess what its for.
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DarkerLine
ceci n'est pas une |


Super Elite (Last Title)


Joined: 04 Nov 2003
Posts: 8328
Posted: 12 Jan 2009 12:37:14 pm    Post subject:
At the very least, I think there should be a defined goal for the obfuscated code. A=B+C is a good start. Maybe later someone could write obfuscated code for something cooler like drawing a line.

My entry for an obfuscated A=B+C:

di (this may well be unnecessary)
ld a, c
srl a
srl b
ld r, a
djnz $
ld a, r
rla
srl c
adc a, -4


Last edited by Guest on 11 Jul 2010 06:46:27 pm; edited 1 time in total
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darkstone knight


Advanced Member


Joined: 07 Sep 2008
Posts: 438
Posted: 12 Jan 2009 01:17:42 pm    Post subject:
does that actualy work?
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DarkerLine
ceci n'est pas une |


Super Elite (Last Title)


Joined: 04 Nov 2003
Posts: 8328
Posted: 12 Jan 2009 01:32:40 pm    Post subject:
Wouldn't you like to know?

It worked for me when I tried it on an emulator.
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darkstone knight


Advanced Member


Joined: 07 Sep 2008
Posts: 438
Posted: 12 Jan 2009 04:41:20 pm    Post subject:
ah, i made a mistake on the djnz...

nevermind..
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Galandros


Active Member


Joined: 29 Aug 2008
Posts: 565
Posted: 12 Jan 2009 05:09:28 pm    Post subject:
Load from memory:

Code:
ld hl,data
xor a
add a,(hl)


random generator Neutral

Code:
ld bc,FFh
ld hl,pointsometioscode;(somewhere in TI-OS or data)
ld de,pointsometioscode
tryagain:
ld a,r
cpir
ld a,b
or c
jr z,tryagain
sbc hl,de
ld a,l



This serve?
DarkerLine was the best (or worst, depends) in my opinion...
EDIT: corrected nick

Last edited by Guest on 12 Jan 2009 05:11:10 pm; edited 1 time in total
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darkstone knight


Advanced Member


Joined: 07 Sep 2008
Posts: 438
Posted: 13 Jan 2009 04:36:04 am    Post subject:
you should use random numbers based on the checksum of the graph buffer Very Happy
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Galandros


Active Member


Joined: 29 Aug 2008
Posts: 565
Posted: 13 Jan 2009 12:34:28 pm    Post subject:
darkstone knight wrote:
you should use random numbers based on the checksum of the graph buffer Very Happy
I love it. And also shadowtext! :biggrin:

And I had a great idea to confuse even more things. I will do it some day. Razz

Last edited by Guest on 13 Jan 2009 12:36:39 pm; edited 1 time in total
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darkstone knight


Advanced Member


Joined: 07 Sep 2008
Posts: 438
Posted: 13 Jan 2009 03:44:35 pm    Post subject:
by the way, what is the fastest checksum code?
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FloppusMaximus


Advanced Member


Joined: 22 Aug 2008
Posts: 472
Posted: 13 Jan 2009 04:33:44 pm    Post subject:
That would have to depend on what you're doing.

For a simple 8-bit checksum I don't see any way to improve on

Code:
   xor a
loop:
   add a,(hl)
   inc hl
   djnz loop

(unless of course you know that L + B < 257, in which case use "inc l" instead of "inc hl".)

If you want to add up more than 256 bytes, it will be faster if you use a double loop rather than a 16-bit counter:

Code:
   dec bc
   inc b
   inc c
   ld a,b
   ld b,c
   ld c,a
   xor a
loop:
   add a,(hl)
   inc hl
   djnz loop
   dec c
   jp nz,loop


If you want a 16-bit result, use the carry flag (I haven't fully convinced myself that this is the fastest possible, but it's the best I can think of):

Code:
   xor a
   ld d,a
loop:
   add a,(hl)
   jr nc,noincr
   inc d
noincr:
   inc hl
   djnz loop
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cjgone
Aw3s0m3


Active Member


Joined: 24 May 2006
Posts: 693
Posted: 14 Jan 2009 01:34:13 am    Post subject:
Oh man, i'm so freakin' brutal at obfuscation.

Look at this


Code:
add a,b ; very verbose addition


Oh yeaa...
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bananaman
Indestructible


Calc Guru


Joined: 12 Sep 2005
Posts: 1124
Posted: 14 Jan 2009 07:15:54 am    Post subject:
Aaaahhhhh, but we were trying to do A=B+C

Code:
ld a,b
add a,c ; a=b+c
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WikiGuru
ADOS (Attention deficit... Oh! Shiny!)


Elite


Joined: 15 Sep 2005
Posts: 923
Posted: 14 Jan 2009 06:11:03 pm    Post subject:
which would make cjgone's very obfuscated indeed.
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darkstone knight


Advanced Member


Joined: 07 Sep 2008
Posts: 438
Posted: 15 Jan 2009 03:09:15 am    Post subject:
isnt the checksum the amount of set bits in a number?

10010000 becomes 2..
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