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@@ -36,6 +36,11 @@
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#define BN_MP_MUL_2_C
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#endif /* LTM_FAST_EXPTMOD */
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+#ifdef LTM_FAST_SQR
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+/* Include faster sqr at the cost of about 0.5 kB in code */
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+#define BN_FAST_S_MP_SQR_C
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+#endif /* LTM_FAST_SQR */
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+
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/* Current uses do not require support for negative exponent in exptmod, so we
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* can save about 1.5 kB in leaving out invmod. */
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#define LTM_NO_NEG_EXP
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@@ -153,6 +158,9 @@ static int mp_init_size(mp_int * a, int size);
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#ifdef BN_MP_EXPTMOD_FAST_C
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static int mp_exptmod_fast (mp_int * G, mp_int * X, mp_int * P, mp_int * Y, int redmode);
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#endif /* BN_MP_EXPTMOD_FAST_C */
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+#ifdef BN_FAST_S_MP_SQR_C
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+static int fast_s_mp_sqr (mp_int * a, mp_int * b);
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+#endif /* BN_FAST_S_MP_SQR_C */
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@@ -2988,3 +2996,99 @@ LBL_M:
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return err;
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}
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#endif
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+
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+
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+#ifdef BN_FAST_S_MP_SQR_C
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+/* the jist of squaring...
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+ * you do like mult except the offset of the tmpx [one that
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+ * starts closer to zero] can't equal the offset of tmpy.
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+ * So basically you set up iy like before then you min it with
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+ * (ty-tx) so that it never happens. You double all those
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+ * you add in the inner loop
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+
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+After that loop you do the squares and add them in.
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+*/
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+
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+static int fast_s_mp_sqr (mp_int * a, mp_int * b)
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+{
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+ int olduse, res, pa, ix, iz;
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+ mp_digit W[MP_WARRAY], *tmpx;
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+ mp_word W1;
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+
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+ /* grow the destination as required */
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+ pa = a->used + a->used;
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+ if (b->alloc < pa) {
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+ if ((res = mp_grow (b, pa)) != MP_OKAY) {
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+ return res;
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+ }
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+ }
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+
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+ /* number of output digits to produce */
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+ W1 = 0;
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+ for (ix = 0; ix < pa; ix++) {
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+ int tx, ty, iy;
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+ mp_word _W;
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+ mp_digit *tmpy;
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+
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+ /* clear counter */
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+ _W = 0;
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+
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+ /* get offsets into the two bignums */
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+ ty = MIN(a->used-1, ix);
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+ tx = ix - ty;
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+
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+ /* setup temp aliases */
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+ tmpx = a->dp + tx;
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+ tmpy = a->dp + ty;
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+
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+ /* this is the number of times the loop will iterrate, essentially
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+ while (tx++ < a->used && ty-- >= 0) { ... }
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+ */
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+ iy = MIN(a->used-tx, ty+1);
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+
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+ /* now for squaring tx can never equal ty
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+ * we halve the distance since they approach at a rate of 2x
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+ * and we have to round because odd cases need to be executed
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+ */
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+ iy = MIN(iy, (ty-tx+1)>>1);
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+
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+ /* execute loop */
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+ for (iz = 0; iz < iy; iz++) {
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+ _W += ((mp_word)*tmpx++)*((mp_word)*tmpy--);
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+ }
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+
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+ /* double the inner product and add carry */
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+ _W = _W + _W + W1;
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+
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+ /* even columns have the square term in them */
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+ if ((ix&1) == 0) {
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+ _W += ((mp_word)a->dp[ix>>1])*((mp_word)a->dp[ix>>1]);
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+ }
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+
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+ /* store it */
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+ W[ix] = (mp_digit)(_W & MP_MASK);
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+
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+ /* make next carry */
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+ W1 = _W >> ((mp_word)DIGIT_BIT);
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+ }
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+
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+ /* setup dest */
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+ olduse = b->used;
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+ b->used = a->used+a->used;
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+
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+ {
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+ mp_digit *tmpb;
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+ tmpb = b->dp;
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+ for (ix = 0; ix < pa; ix++) {
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+ *tmpb++ = W[ix] & MP_MASK;
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+ }
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+
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+ /* clear unused digits [that existed in the old copy of c] */
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+ for (; ix < olduse; ix++) {
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+ *tmpb++ = 0;
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+ }
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+ }
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+ mp_clamp (b);
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+ return MP_OKAY;
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+}
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+#endif
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