bigtest.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include <u.h>
#include <libc.h>
#include <mp.h>
#include <libsec.h>

char *sfactors[] =
{	"3", "5", "17", "257", "641", "65537", "274177", "2424833", "6700417", "45592577",
    "6487031809", "67280421310721", "1238926361552897", "59649589127497217",
    "5704689200685129054721", "4659775785220018543264560743076778192897",
    "7455602825647884208337395736200454918783366342657",
    "93461639715357977769163558199606896584051237541638188580280321",

    "741640062627530801524787141901937474059940781097519023905821316144415759504705008092818711693940737",

    "130439874405488189727484768796509903946608530841611892186895295776832416251471863574140227977573104895898783928842923844831149032913798729088601617946094119449010595906710130531906171018354491609619193912488538116080712299672322806217820753127014424577"
};

long start;

void
printmp(mpint *b, char *tag)
{
	int n;
	char *p;

	print("%s (%d) ", tag, b->top);
	p = mptoa(b, 10, nil, 0);
	write(1, p, strlen(p));
	free(p);
	print("\n");
}

int
timing(void)
{
	long now, span;

	now = time(0);
	span = now-start;
	start = now;

	return span;
}

int expdebug;


void
main(int argc, char **argv)
{
	mpint *p, *k, *d, *b, *e, *x, *r;
	int i;

	start = time(0);
	fmtinstall('B', mpconv);
	mpsetminbits(2*Dbits);

	x = mpnew(0);
	e = mpnew(0);
	r = mpnew(0);
	p = mpnew(0);

	// b = 2^32
	b = mpcopy(mpone);
	mpleft(b, 32, b);

	// 2^29440
	p = mpcopy(mpone);
	mpleft(p, 29440, p);
	// 2^27392
	k = mpcopy(mpone);
	mpleft(k, 27392, k);
	// k = 2^29440 - 2^27392
	mpsub(p, k, k);
	// p = 2^29440 - 2^27392 + 1
	mpadd(k, mpone, p);

//	if(!probably_prime(p, 18)){
//		print("not a prime\n");
//		exits(0);
//	}
//	print("probably prime\n");

	mpright(k, 10, k);
	printmp(k, "k =");

expdebug = 1;
	mpexp(b, k, p, x);
	printmp(x, "x =");
	print("timing %d\n", timing());

	for(i = 0; i < nelem(sfactors); i++){
		d = strtomp(sfactors[i], nil, 10, nil);
		// e = k/d
		mpdiv(k, d, e, r);
		printmp(r, "r =");

		// x = b^e mod p
		mpexp(b, e, p, x);
		printmp(x, "x =");
		print("timing %d\n", timing());
	}
}