Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>
#include <bio.h>

#define whsiz   (sizeof(wheel)/sizeof(wheel[0]))

double  wheel[] =
{
         2,10, 2, 4, 2, 4, 6, 2, 6, 4,
         2, 4, 6, 6, 2, 6, 4, 2, 6, 4,
         6, 8, 4, 2, 4, 2, 4, 8, 6, 4,
         6, 2, 4, 6, 2, 6, 6, 4, 2, 4,
         6, 2, 6, 4, 2, 4, 2,10,
};

Biobuf  bin;

void    factor(double);

void
main(int argc, char *argv[])
{
        double n;
        int i;
        char *l;

        if(argc > 1) {
                for(i=1; i<argc; i++) {
                        n = atof(argv[i]);
                        factor(n);
                }
                exits(0);
        }

        Binit(&bin, 0, OREAD);
        for(;;) {
                l = Brdline(&bin, '\n');
                if(l ==  0)
                        break;
                n = atof(l);
                if(n <= 0)
                        break;
                factor(n);
        }
        exits(0);
}

void
factor(double n)
{
        double quot, d, s;
        int i;

        print("%.0f\n", n);
        if(n == 0)
                return;
        s = sqrt(n) + 1;
        while(modf(n/2, &quot) == 0) {
                print("     2\n");
                n = quot;
                s = sqrt(n) + 1;
        }
        while(modf(n/3, &quot) == 0) {
                print("     3\n");
                n = quot;
                s = sqrt(n) + 1;
        }
        while(modf(n/5, &quot) == 0) {
                print("     5\n");
                n = quot;
                s = sqrt(n) + 1;
        }
        while(modf(n/7, &quot) == 0) {
                print("     7\n");
                n = quot;
                s = sqrt(n) + 1;
        }
        d = 1;
        for(i=1;;) {
                d += wheel[i];
                while(modf(n/d, &quot) == 0) {
                        print("     %.0f\n", d);
                        n = quot;
                        s = sqrt(n) + 1;
                }
                i++;
                if(i >= whsiz) {
                        i = 0;
                        if(d > s)
                                break;
                }
        }
        if(n > 1)
                print("     %.0f\n",n);
        print("\n");
}