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Index > Main > What is the "Equation" of XOR (Bitwise)? (If there

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typedef



Joined: 25 Jul 2010
Posts: 2913
Location: 0x77760000
typedef
What is the equation of XOR?
For example

let's say this is the standard form of XOR

A xor B

6 xor 4 = 2;

So,

Is it ( A xor B = ( A > B) ? A - B : B - A; (but either way the result is 2).

So I say that's not the way it is computed.

Let A=9 & Let B=12

A xor B = 5.. How, i was expecting 3 (LOL)


It looks like there are some conditions inside it.


Anyhbody know, I asked Google and all he said was the Boolean XOR equation. I interrogated him but still he refused to say. Very Happy
Post 19 Apr 2011, 00:41
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asmhack



Joined: 01 Feb 2008
Posts: 431
asmhack
Code:
110 ;6
100 ;4
____
010 ;2



1001 ;9
1100 ;12
____
0101 ;5
    


xor is a digital logic gate that implements an exclusive disjunction, not absolute subtraction, that's the conditions.
Post 19 Apr 2011, 00:55
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17658
Location: In your JS exploiting you and your system
revolution
XOR is the same as addition (and subtraction) but without any internal carries propagated.

For each bit in the operand:

0+0=0
0+1=1
1+0=1
1+1=0 (ignore the carry)

Works for subtraction also:

0-0=0
0-1=1 (ignore the carry)
1-0=1
1-1=0

The mathematical equivalent would be: bitwise A + B = C mod 2
Post 19 Apr 2011, 01:01
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typedef



Joined: 25 Jul 2010
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typedef
Oh, so the trick is to just convert from whatever base you are in to base 2 and then use the truth table ?.......
Post 19 Apr 2011, 01:12
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
Posts: 17658
Location: In your JS exploiting you and your system
revolution
AFAIK XOR is only defined in the binary domain. "boolean" is the word that should alert you to it being binary.
Post 19 Apr 2011, 01:24
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bitRAKE



Joined: 21 Jul 2003
Posts: 3032
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bitRAKE
A xor B = (A or B) and ((not A) or (not B))
...and the wiki has several alternatives.
Post 19 Apr 2011, 02:12
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bitshifter



Joined: 04 Dec 2007
Posts: 764
Location: Massachusetts, USA
bitshifter
My BitBox helps to visualize such things...
http://board.flatassembler.net/topic.php?t=11615
Have fun Smile
Post 19 Apr 2011, 10:45
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