static int
testmult(void)
{
mp_mult(c5, c2, t0);
testmcmp(t0, c10, "mmult0");
mp_mult(c3, c14, t0);
testmcmp(t0, c42, "mmult1");
}
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);
}
/* Converts a possibly-signed digit string into a large binary number.
Returns assumed radix, derived from suffix 'h','o',b','.' */
int str2reg(unitptr reg, string digitstr)
{
unit temp[MAX_UNIT_PRECISION], base[MAX_UNIT_PRECISION];
int c, i;
boolean minus = FALSE;
short radix; /* base 2-16 */
mp_init(reg, 0);
i = string_length(digitstr);
if (i == 0)
return (10); /* empty string, assume radix 10 */
c = digitstr[i - 1]; /* get last char in string */
switch (c) { /* classify radix select suffix character */
case '.':
radix = 10;
break;
case 'H':
case 'h':
radix = 16;
break;
case 'O':
case 'o':
radix = 8;
break;
case 'B': /* caution! 'b' is a hex digit! */
case 'b':
radix = 2;
break;
default:
radix = 10;
break;
}
mp_init(base, radix);
if ((minus = (*digitstr == '-')) != 0)
digitstr++;
while ((c = *digitstr++) != 0) {
if (c == ',')
continue; /* allow commas in number */
c = ctox(c);
if ((c < 0) || (c >= radix))
break; /* scan terminated by any non-digit */
mp_mult(temp, reg, base);
mp_move(reg, temp);
mp_init(temp, c);
mp_add(reg, temp);
}
if (minus)
mp_neg(reg);
return (radix);
} /* str2reg */
static int
m_in(MINT *a, short b, FILE *f)
{
MINT x, y, ten;
int sign, c;
short qten, qy;
_mp_xfree(a);
sign = 1;
ten.len = 1;
ten.val = &qten;
qten = b;
x.len = 0;
y.len = 1;
y.val = &qy;
while ((c = getc(f)) != EOF)
switch (c) {
case '\\':
(void) getc(f);
continue;
case '\t':
case '\n':
a->len *= sign;
_mp_xfree(&x);
return (0);
case ' ':
continue;
case '-':
sign = -sign;
continue;
default:
if (c >= '0' && c <= '9') {
qy = c - '0';
mp_mult(&x, &ten, a);
mp_madd(a, &y, a);
_mp_move(a, &x);
continue;
} else {
(void) ungetc(c, stdin);
a->len *= sign;
return (0);
}
}
return (EOF);
}
void mult(MINT *a, MINT *b, MINT *c) { mp_mult(a, b, c); }
