cellular automata printer

ca.c

/*
 * Cellular Automata Printer
 *
 * Usage: binary-name [RULE INITAL] 
 * where RULE sets the CA rule (def. 30)
 * and  INITIAL the initial hex start pattern 
 * (def. 0x100000000 i.e. a centered 1).
 *
 * All rights reversed.
 * 2012 Remo Giermann <mo@liberejo.de>
 */

#include <stdio.h>

int main(int argc, const char *argv[])
{
        long i, w=0, r=30, g=1L<<32;
        if (argc == 3) {
                sscanf(argv[1], "%u", &r);
                sscanf(argv[2], "%lx", &g);
        }
        while (1) {
                for (w=g,i=1,g=0; i<sizeof(long)*8; i++) {
                        long nbhood = (w&(7L<<(i-1)))>>(i-1);
                        g |= (r&(1L<<nbhood))<<(i-nbhood);
                        putchar(w&(1L<<i)?'X':' ');
                }
                if (w == g || (w&(1L<<63) && w&(1L<<1))) break;
                putchar(10); usleep(10000);
        }
        return 0;
}