#define BN_S_MP_SQR_C
#define BN_S_MP_MUL_HIGH_DIGS_C /* Note: #undef in tommath_superclass.h; this
* would require other than mp_reduce */
+#ifdef LTM_FAST_DIV
+/* Use faster div at the cost of about 1 kB */
+#define BN_MP_MUL_D_C
+#else /* LTM_FAST_DIV */
+#define BN_MP_DIV_SMALL
+#define BN_MP_INIT_MULTI_C
+#define BN_MP_CLEAR_MULTI_C
+#define BN_MP_ABS_C
+#endif /* LTM_FAST_DIV */
#ifdef LTM_FAST_EXPTMOD
/* Include faster exptmod (Montgomery) at the cost of about 2.5 kB in code */
static int fast_s_mp_mul_digs (mp_int * a, mp_int * b, mp_int * c, int digs);
+#ifdef BN_MP_INIT_MULTI_C
static int mp_init_multi(mp_int *mp, ...);
+#endif
+#ifdef BN_MP_CLEAR_MULTI_C
static void mp_clear_multi(mp_int *mp, ...);
+#endif
static int mp_lshd(mp_int * a, int b);
static void mp_set(mp_int * a, mp_digit b);
static void mp_clamp(mp_int * a);
static int mp_mod(mp_int * a, mp_int * b, mp_int * c);
static int mp_grow(mp_int * a, int size);
static int mp_cmp_mag(mp_int * a, mp_int * b);
+#ifdef BN_MP_ABS_C
static int mp_abs(mp_int * a, mp_int * b);
+#endif
static int mp_sqr(mp_int * a, mp_int * b);
static int mp_reduce_2k_l(mp_int *a, mp_int *n, mp_int *d);
static int mp_reduce_2k_setup_l(mp_int *a, mp_int *d);
#ifdef BN_FAST_S_MP_SQR_C
static int fast_s_mp_sqr (mp_int * a, mp_int * b);
#endif /* BN_FAST_S_MP_SQR_C */
+#ifdef BN_MP_MUL_D_C
+static int mp_mul_d (mp_int * a, mp_digit b, mp_int * c);
+#endif /* BN_MP_MUL_D_C */
}
+#ifdef BN_MP_ABS_C
/* b = |a|
*
* Simple function copies the input and fixes the sign to positive
return MP_OKAY;
}
+#endif
/* set to a digit */
}
+#ifdef BN_MP_INIT_MULTI_C
static int mp_init_multi(mp_int *mp, ...)
{
mp_err res = MP_OKAY; /* Assume ok until proven otherwise */
va_end(args);
return res; /* Assumed ok, if error flagged above. */
}
+#endif
+#ifdef BN_MP_CLEAR_MULTI_C
static void mp_clear_multi(mp_int *mp, ...)
{
mp_int* next_mp = mp;
}
va_end(args);
}
+#endif
/* shift left a certain amount of digits */
}
+#ifdef BN_MP_DIV_SMALL
+
/* slower bit-bang division... also smaller */
static int mp_div(mp_int * a, mp_int * b, mp_int * c, mp_int * d)
{
return res;
}
+#else
+
+/* integer signed division.
+ * c*b + d == a [e.g. a/b, c=quotient, d=remainder]
+ * HAC pp.598 Algorithm 14.20
+ *
+ * Note that the description in HAC is horribly
+ * incomplete. For example, it doesn't consider
+ * the case where digits are removed from 'x' in
+ * the inner loop. It also doesn't consider the
+ * case that y has fewer than three digits, etc..
+ *
+ * The overall algorithm is as described as
+ * 14.20 from HAC but fixed to treat these cases.
+*/
+static int mp_div (mp_int * a, mp_int * b, mp_int * c, mp_int * d)
+{
+ mp_int q, x, y, t1, t2;
+ int res, n, t, i, norm, neg;
+
+ /* is divisor zero ? */
+ if (mp_iszero (b) == 1) {
+ return MP_VAL;
+ }
+
+ /* if a < b then q=0, r = a */
+ if (mp_cmp_mag (a, b) == MP_LT) {
+ if (d != NULL) {
+ res = mp_copy (a, d);
+ } else {
+ res = MP_OKAY;
+ }
+ if (c != NULL) {
+ mp_zero (c);
+ }
+ return res;
+ }
+
+ if ((res = mp_init_size (&q, a->used + 2)) != MP_OKAY) {
+ return res;
+ }
+ q.used = a->used + 2;
+
+ if ((res = mp_init (&t1)) != MP_OKAY) {
+ goto LBL_Q;
+ }
+
+ if ((res = mp_init (&t2)) != MP_OKAY) {
+ goto LBL_T1;
+ }
+
+ if ((res = mp_init_copy (&x, a)) != MP_OKAY) {
+ goto LBL_T2;
+ }
+
+ if ((res = mp_init_copy (&y, b)) != MP_OKAY) {
+ goto LBL_X;
+ }
+
+ /* fix the sign */
+ neg = (a->sign == b->sign) ? MP_ZPOS : MP_NEG;
+ x.sign = y.sign = MP_ZPOS;
+
+ /* normalize both x and y, ensure that y >= b/2, [b == 2**DIGIT_BIT] */
+ norm = mp_count_bits(&y) % DIGIT_BIT;
+ if (norm < (int)(DIGIT_BIT-1)) {
+ norm = (DIGIT_BIT-1) - norm;
+ if ((res = mp_mul_2d (&x, norm, &x)) != MP_OKAY) {
+ goto LBL_Y;
+ }
+ if ((res = mp_mul_2d (&y, norm, &y)) != MP_OKAY) {
+ goto LBL_Y;
+ }
+ } else {
+ norm = 0;
+ }
+
+ /* note hac does 0 based, so if used==5 then its 0,1,2,3,4, e.g. use 4 */
+ n = x.used - 1;
+ t = y.used - 1;
+
+ /* while (x >= y*b**n-t) do { q[n-t] += 1; x -= y*b**{n-t} } */
+ if ((res = mp_lshd (&y, n - t)) != MP_OKAY) { /* y = y*b**{n-t} */
+ goto LBL_Y;
+ }
+
+ while (mp_cmp (&x, &y) != MP_LT) {
+ ++(q.dp[n - t]);
+ if ((res = mp_sub (&x, &y, &x)) != MP_OKAY) {
+ goto LBL_Y;
+ }
+ }
+
+ /* reset y by shifting it back down */
+ mp_rshd (&y, n - t);
+
+ /* step 3. for i from n down to (t + 1) */
+ for (i = n; i >= (t + 1); i--) {
+ if (i > x.used) {
+ continue;
+ }
+
+ /* step 3.1 if xi == yt then set q{i-t-1} to b-1,
+ * otherwise set q{i-t-1} to (xi*b + x{i-1})/yt */
+ if (x.dp[i] == y.dp[t]) {
+ q.dp[i - t - 1] = ((((mp_digit)1) << DIGIT_BIT) - 1);
+ } else {
+ mp_word tmp;
+ tmp = ((mp_word) x.dp[i]) << ((mp_word) DIGIT_BIT);
+ tmp |= ((mp_word) x.dp[i - 1]);
+ tmp /= ((mp_word) y.dp[t]);
+ if (tmp > (mp_word) MP_MASK)
+ tmp = MP_MASK;
+ q.dp[i - t - 1] = (mp_digit) (tmp & (mp_word) (MP_MASK));
+ }
+
+ /* while (q{i-t-1} * (yt * b + y{t-1})) >
+ xi * b**2 + xi-1 * b + xi-2
+
+ do q{i-t-1} -= 1;
+ */
+ q.dp[i - t - 1] = (q.dp[i - t - 1] + 1) & MP_MASK;
+ do {
+ q.dp[i - t - 1] = (q.dp[i - t - 1] - 1) & MP_MASK;
+
+ /* find left hand */
+ mp_zero (&t1);
+ t1.dp[0] = (t - 1 < 0) ? 0 : y.dp[t - 1];
+ t1.dp[1] = y.dp[t];
+ t1.used = 2;
+ if ((res = mp_mul_d (&t1, q.dp[i - t - 1], &t1)) != MP_OKAY) {
+ goto LBL_Y;
+ }
+
+ /* find right hand */
+ t2.dp[0] = (i - 2 < 0) ? 0 : x.dp[i - 2];
+ t2.dp[1] = (i - 1 < 0) ? 0 : x.dp[i - 1];
+ t2.dp[2] = x.dp[i];
+ t2.used = 3;
+ } while (mp_cmp_mag(&t1, &t2) == MP_GT);
+
+ /* step 3.3 x = x - q{i-t-1} * y * b**{i-t-1} */
+ if ((res = mp_mul_d (&y, q.dp[i - t - 1], &t1)) != MP_OKAY) {
+ goto LBL_Y;
+ }
+
+ if ((res = mp_lshd (&t1, i - t - 1)) != MP_OKAY) {
+ goto LBL_Y;
+ }
+
+ if ((res = mp_sub (&x, &t1, &x)) != MP_OKAY) {
+ goto LBL_Y;
+ }
+
+ /* if x < 0 then { x = x + y*b**{i-t-1}; q{i-t-1} -= 1; } */
+ if (x.sign == MP_NEG) {
+ if ((res = mp_copy (&y, &t1)) != MP_OKAY) {
+ goto LBL_Y;
+ }
+ if ((res = mp_lshd (&t1, i - t - 1)) != MP_OKAY) {
+ goto LBL_Y;
+ }
+ if ((res = mp_add (&x, &t1, &x)) != MP_OKAY) {
+ goto LBL_Y;
+ }
+
+ q.dp[i - t - 1] = (q.dp[i - t - 1] - 1UL) & MP_MASK;
+ }
+ }
+
+ /* now q is the quotient and x is the remainder
+ * [which we have to normalize]
+ */
+
+ /* get sign before writing to c */
+ x.sign = x.used == 0 ? MP_ZPOS : a->sign;
+
+ if (c != NULL) {
+ mp_clamp (&q);
+ mp_exch (&q, c);
+ c->sign = neg;
+ }
+
+ if (d != NULL) {
+ mp_div_2d (&x, norm, &x, NULL);
+ mp_exch (&x, d);
+ }
+
+ res = MP_OKAY;
+
+LBL_Y:mp_clear (&y);
+LBL_X:mp_clear (&x);
+LBL_T2:mp_clear (&t2);
+LBL_T1:mp_clear (&t1);
+LBL_Q:mp_clear (&q);
+ return res;
+}
+
+#endif
+
#ifdef MP_LOW_MEM
#define TAB_SIZE 32
return MP_OKAY;
}
#endif
+
+
+#ifdef BN_MP_MUL_D_C
+/* multiply by a digit */
+static int
+mp_mul_d (mp_int * a, mp_digit b, mp_int * c)
+{
+ mp_digit u, *tmpa, *tmpc;
+ mp_word r;
+ int ix, res, olduse;
+
+ /* make sure c is big enough to hold a*b */
+ if (c->alloc < a->used + 1) {
+ if ((res = mp_grow (c, a->used + 1)) != MP_OKAY) {
+ return res;
+ }
+ }
+
+ /* get the original destinations used count */
+ olduse = c->used;
+
+ /* set the sign */
+ c->sign = a->sign;
+
+ /* alias for a->dp [source] */
+ tmpa = a->dp;
+
+ /* alias for c->dp [dest] */
+ tmpc = c->dp;
+
+ /* zero carry */
+ u = 0;
+
+ /* compute columns */
+ for (ix = 0; ix < a->used; ix++) {
+ /* compute product and carry sum for this term */
+ r = ((mp_word) u) + ((mp_word)*tmpa++) * ((mp_word)b);
+
+ /* mask off higher bits to get a single digit */
+ *tmpc++ = (mp_digit) (r & ((mp_word) MP_MASK));
+
+ /* send carry into next iteration */
+ u = (mp_digit) (r >> ((mp_word) DIGIT_BIT));
+ }
+
+ /* store final carry [if any] and increment ix offset */
+ *tmpc++ = u;
+ ++ix;
+
+ /* now zero digits above the top */
+ while (ix++ < olduse) {
+ *tmpc++ = 0;
+ }
+
+ /* set used count */
+ c->used = a->used + 1;
+ mp_clamp(c);
+
+ return MP_OKAY;
+}
+#endif
projects / libeap.git / commitdiff