recursive Macros - Dev Shed

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June 26th, 2003, 05:12 AM

djwilliams37

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Location: Gloucester, Glos

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recursive Macros

does anyone know how to decifer this macro, I know what it basically does but want to convert it to a standard function. The code is from Deep Sea secrets and is a BASIC interpreter from the Ofuscated code copetition. The macro O() is called by means of its
b parameter. It looks like some deep nested recursion is going on here. Any one got any ideas.
Thanks
Dave.

define O(b,f,u,s,c,a)b(){\
int o=f();\
switch(*p++){\
case u:return o s b();\
case c :return o a b()\
default

--;return o;}\
}

//Macro calls
O(S,J,'=',==,'#',!=);
O(J,K,'<',<,'>',>);
O(K,V,'$',<=,'!',>=);
O(V,W,'+',+,'-',-);
O(W,Y,'*',*,'/',/)Y()
{

int o;

return(*p=='-')? (p++,-Y()) //recursive call of Y() here

*p>='0'&&*p<='9')? (strtol(p,&p,0))
: (*p=='(')?(p++,o=S(),p++,o): (P[*p++]);

}

June 26th, 2003, 07:32 AM

Analyser

*bounce*

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Location: Delft, The Netherlands

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Try running it through the preprocessor only. If you're using GCC, something like the following may do the trick:

Code:

gcc -E obfuscated.c > nomacros.c

With obfuscated.c being the source you just posted, and nomacros.c being the file containing the "de-obfuscated" code.

Good luck

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June 26th, 2003, 09:15 AM

balance

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i just got hold of some obfuscated code. it draws a maze. what gets me is that there's a rand in there but the maze, i think, is the same every time - seems a bit strange.

here it is with some returns and tabs in (it was one big block) :

Code:

#define P(X)j=write(1,X,1)
#define C 39

int M[5000] = {2}, *u = M, N[5000], R = 22, a[4], l[] = {0,-1,C-1,-1}, m[] = {1,-C,-1,C}, *b = N, *d = N, c, e, f, g, i, j, k, s;

main()
{
	for(M[i = C*R - 1] = 24; f|d >= b; ) {
		c = M[g = i];
		i = e;
		for( s=f=0; s < 4; s++)
			if((k = m[s] + g) >= 0 && k < C *R && l [s] != k % C && (!M[k] || !j && c >= 16 != M[k] >= 16))
				a[f++] = s;
				if(f) {
					f = M[e = m[s = a[rand() / (1 + 2147483647 / f)]] + g];
					j = j < f ? f : j;
					f += c & -16 * !j;
					M[g] = c | 1 << s;
					M[*d++ = e] = f | 1 << (s + 2) % 4;
				} else
					e = d > b++ ? b[-1] : e;
			}
		P(" ");
		for(s = C; --s; P("_")) P(" ")
			;
		for( ; P("\n"), R--; P("|"))
			for(e = C; e--; P("_ "+(*u++ / 8) % 2)) P("| "+(*u/4) % 2)
				;
}

Code:

  _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
|_   _ _|     |_  |_ _ _  |  _  |  _  |   |  _ _ _  |_ _ _ _ _ _   _ _ _|  _  |
|  _ _ _ _| |_ _ _|  _ _ _ _|_ _|_  |_ _|_ _|_    |_ _  | |  _ _ _ _ _  | |  _|
|   |  _  |  _ _  | |_ _   _|  _  | |  _   _ _ _| | |   |_ _|   |_    |_ _| | |
| |_ _|   |  _  |_ _|  _ _  |_  | | | |   |_ _   _|_ _|_ _|  _|_  | |_  |  _| |
|_ _ _| | | |  _ _ _ _|_  | |  _|_  |_| |_|   | |   |  _  | |_ _ _|_ _| | |   |
|   |  _|_| | |    _ _ _ _|_| |  _ _|   |  _| | | |_ _| |_ _|  _ _  |  _|_ _| |
| |_ _|_ _ _| | |_ _ _  |  _ _| | |  _|_| |_ _|_  |   |   |_ _ _  | |_ _ _    |
| |  _  |  _ _| |   |_ _|_ _ _| |_ _|_  | |  _ _  | | | |_|  _|  _|_ _ _ _  | |
| |_  |_  |   |_ _|_ _   _ _|  _|   |  _| | |   |_| | |_  | |  _|  _ _ _  | | |
| |  _| | | |_ _ _ _ _ _|  _ _|_ _| | | |  _| |_ _ _|_    | |_ _|_ _|  _ _| | |
| |   |_ _|  _|  _ _  |  _|   |  _ _|  _ _|  _|  _   _ _| |  _  |  _ _| |  _| |
| | |_ _ _ _ _ _|_  |_ _| | | | |   | |_  |_ _| |  _| |  _| | | | |    _| |  _|
| |_  |  _ _   _  |  _  |_ _| |_ _| |_  |_ _ _ _| |  _|_  | | |_ _| |_ _ _|_  |
| |_ _| |  _ _ _| |   |_ _ _  |  _ _| |_  |  _ _ _| | |  _| | |   | | | |   | |
|    _ _|_  |   | |_|_ _  | | |  _ _  | | |_ _  |  _|  _|  _| | |_|  _| | |_ _|
| | |_  | |   | |_  |   |_ _| | |_  | |  _|  _  |_  | |_  |  _ _|  _ _ _|_ _ _|
| |_ _ _| |_| |_  |_ _|_ _ _| | |  _| | |   |_ _|  _|_  | | |  _ _|  _   _ _  |
|    _  |_  |_  |     |  _ _   _| |  _| | | |   |_ _   _|   |_ _  | |   | |  _|
| |_  |   | |_ _| | |  _|   |_ _  |_ _ _| | | |_ _  | |   |_  |   |_|_|_ _|_  |
|_  |_| | |_  | | | |_ _ _| |  _ _ _ _  | |_|_ _ _| |_ _|_  | | | |     |  _| |
| |_  | |_ _|_  | | |   |_ _|_|   |_  | |_  |  _ _ _ _ _ _ _|_ _| |_| | |    _|
|_ _ _|_ _ _ _ _|_|_ _|_ _ _ _ _|_ _ _|_ _ _|_ _ _ _ _ _ _ _ _ _|_ _ _|_ _|_  |

god knows how it works really. i haven't tried that pre-processor thing on it though. will do though.

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