static int
testsimpel(void)
{
const char str42[] = "2a";
MINT *t2;
char *s;
mp_madd(c42, c1, t0);
testmcmp(c43, t0, "madd0");
mp_madd(t0, c1, t0);
testmcmp(c44, t0, "madd1");
mp_msub(t0, c1, t0);
testmcmp(c43, t0, "msub0");
mp_msub(t0, c1, t0);
testmcmp(c42, t0, "msub1");
mp_move(c42, t0);
testmcmp(c42, t0, "move0");
t2 = mp_xtom(str42);
testmcmp(c42, t2, "xtom");
s = mp_mtox(t2);
if (strcmp(str42, s) == 0)
printf("ok %d - %s\n", ++tnr, "mtox0");
else
printf("not ok %d - %s\n", ++tnr, "mtox0");
mp_mfree(t2);
}
void
mp_invert(MINT *x1, MINT *x0, MINT *c)
{
MINT u2, u3;
MINT v2, v3;
MINT zero;
MINT q, r;
MINT t;
MINT x0_prime;
static MINT *one = NULL;
/*
* Minimize calls to allocators. Don't use pointers for local
* variables, for the one "initialized" multiple precision
* variable, do it just once.
*/
if (one == NULL)
one = mp_itom(1);
zero.len = q.len = r.len = t.len = 0;
x0_prime.len = u2.len = u3.len = 0;
_mp_move(x0, &u3);
_mp_move(x0, &x0_prime);
v2.len = v3.len = 0;
_mp_move(one, &v2);
_mp_move(x1, &v3);
while (mp_mcmp(&v3, &zero) != 0) {
/* invariant: x0*u1 + x1*u2 = u3 */
/* invariant: x0*v1 + x2*v2 = v3 */
/* invariant: x(n+1) = x(n-1) % x(n) */
mp_mdiv(&u3, &v3, &q, &r);
_mp_move(&v3, &u3);
_mp_move(&r, &v3);
mp_mult(&q, &v2, &t);
mp_msub(&u2, &t, &t);
_mp_move(&v2, &u2);
_mp_move(&t, &v2);
}
/* now x0*u1 + x1*u2 == 1, therefore, (u2*x1) % x0 == 1 */
_mp_move(&u2, c);
if (mp_mcmp(c, &zero) < 0) {
mp_madd(&x0_prime, c, c);
}
_mp_xfree(&zero);
_mp_xfree(&v2);
_mp_xfree(&v3);
_mp_xfree(&u2);
_mp_xfree(&u3);
_mp_xfree(&q);
_mp_xfree(&r);
_mp_xfree(&t);
}
void
mp_msub(MINT *a, MINT *b, MINT *c)
{
MINT x, y;
int sign;
x.len = y.len = 0;
_mp_move(a, &x);
_mp_move(b, &y);
_mp_xfree(c);
sign = 1;
if (x.len >= 0) {
if (y.len >= 0) {
if (x.len >= y.len) {
m_sub(&x, &y, c);
} else {
sign = -1;
mp_msub(&y, &x, c);
}
} else {
y.len = -y.len;
mp_madd(&x, &y, c);
}
} else {
if (y.len <= 0) {
x.len = -x.len;
y.len = -y.len;
mp_msub(&y, &x, c);
} else {
x.len = -x.len;
mp_madd(&x, &y, c);
sign = -1;
}
}
c->len = sign * c->len;
_mp_xfree(&x);
_mp_xfree(&y);
}
void msub(MINT *a, MINT *b, MINT *c) { mp_msub(a, b, c); }
