deobfuscated-buzzard.2.c

// deobfuscated version of "FIRST and THIRD"
// deobfuscated by Sofia Faro (@typeswitch)
// original by Sean Barrett (@nothings)
//
// original design document: ftp.funet.fi/pub/doc/IOCCC/1992/buzzard.2.design
// original obfuscated code: ftp.funet.fi/pub/doc/IOCCC/1992/buzzard.2.c

#define comma m[m[0]++] =

char s[5000];
int m[20000]={32},L=1,IP,T[500],*S=T,t=64,w,f;
void create(x) {
   comma L;
   L= *m-1;
   comma t;
   comma x;
   scanf("%s",s+t);
   t+=strlen(s+t)+1;
}

void run(x) {
   	switch (m[x++]){
		case 0: // lit
			*++S=f;
			f=m[IP++];
			break;
		case 1: // default compile action, which is to comma the xt
			comma x;
			break;
	 	case 2: // docolon op, which pushes IP on RS and gives a new IP
			m[++m[1]]=IP;
			IP=x;
			break;
		case 3: // : -- makes an activation which just pushes
			create(1);
			comma 2;
			break;
		case 4: // immediate -- overwrites the compile op with docol,
                // and moves HERE back to compensate
			*m-=2;
			comma 2;
			break;
		case 5: // read_ ?
			if (scanf("%s",s) < 1) exit(0);
			for(w=L; strcmp(s, &s[m[w+1]]) != 0; w=m[w]);
			// last link L is 1 (see that L=1 initially)
			// m[2] has to be zero for this loop to finish
			// basically w=1 here means we didn't find a word
			// in the dictionary, but m[2] being zero means we're
			// comparing s against itself, which is a convenient way to stop
			if (w != 1) { // no string
				run(w+2); // run compile xt
			} else {
				comma 2 // m[2]=0 means the corresponding operator is lit
				comma atoi(s) // push integer value
			}
			break;
		case 6: // load @
			f=m[f];
			break;
		case 7: // store !
			m[f]= *S--;
			f= *S--;
			break;
		case 8: // subtraction -
			f= *S-- - f;
			break;
		case 9: // multiplication *
			f *= *S--;
			break;
		case 10: // division /
			f= *S-- / f;
			break;
		case 11: // is-negative <0
			f=0>f;
			break;
		case 12: // exit, i.e. return from function
			IP=m[m[1]--];
			break;
		case 13: // echo, i.e. emit character to stdout
			putchar(f);
			f= *S--;
			break;
		case 14: // key, i.e. get character from stdin
			*++S=f;
			f=getchar();
		case 15: // _pick, not really used
			f=S[-f];
			break;
   }
}

main()
{
	create(3);
	create(4);
	create(1);
	w= *m;
	comma 5;
	comma 2;
	IP= *m;
	comma w;
	comma IP-1;
	for(w=6;w<16;)
		create(1),comma w++;
	m[1]= *m;
	*m += 512;
	while(1)
   		run(m[IP++]);
}