+ if (--j > 0) {
+ ap++;
+ rp[j] = bn_mul_words(rp, ap, j, ap[-1]);
+ rp += 2;
+ }
+
+ for (i = n - 2; i > 0; i--) {
+ j--;
+ ap++;
+ rp[j] = bn_mul_add_words(rp, ap, j, ap[-1]);
+ rp += 2;
+ }
+
+ bn_add_words(r, r, r, max);
+
+ /* There will not be a carry */
+
+ bn_sqr_words(tmp, a, n);
+
+ bn_add_words(r, r, tmp, max);
+}
+
+#ifdef BN_RECURSION
+/*-
+ * r is 2*n words in size,
+ * a and b are both n words in size. (There's not actually a 'b' here ...)
+ * n must be a power of 2.
+ * We multiply and return the result.
+ * t must be 2*n words in size
+ * We calculate
+ * a[0]*b[0]
+ * a[0]*b[0]+a[1]*b[1]+(a[0]-a[1])*(b[1]-b[0])
+ * a[1]*b[1]
+ */
+void bn_sqr_recursive(BN_ULONG *r, const BN_ULONG *a, int n2, BN_ULONG *t)
+{
+ int n = n2 / 2;
+ int zero, c1;
+ BN_ULONG ln, lo, *p;
+
+ if (n2 == 4) {
+# ifndef BN_SQR_COMBA
+ bn_sqr_normal(r, a, 4, t);
+# else
+ bn_sqr_comba4(r, a);
+# endif
+ return;
+ } else if (n2 == 8) {
+# ifndef BN_SQR_COMBA
+ bn_sqr_normal(r, a, 8, t);
+# else
+ bn_sqr_comba8(r, a);
+# endif
+ return;
+ }
+ if (n2 < BN_SQR_RECURSIVE_SIZE_NORMAL) {
+ bn_sqr_normal(r, a, n2, t);
+ return;
+ }
+ /* r=(a[0]-a[1])*(a[1]-a[0]) */
+ c1 = bn_cmp_words(a, &(a[n]), n);
+ zero = 0;
+ if (c1 > 0)
+ bn_sub_words(t, a, &(a[n]), n);
+ else if (c1 < 0)
+ bn_sub_words(t, &(a[n]), a, n);
+ else
+ zero = 1;
+
+ /* The result will always be negative unless it is zero */
+ p = &(t[n2 * 2]);
+
+ if (!zero)
+ bn_sqr_recursive(&(t[n2]), t, n, p);
+ else
+ memset(&t[n2], 0, sizeof(*t) * n2);
+ bn_sqr_recursive(r, a, n, p);
+ bn_sqr_recursive(&(r[n2]), &(a[n]), n, p);
+
+ /*-
+ * t[32] holds (a[0]-a[1])*(a[1]-a[0]), it is negative or zero
+ * r[10] holds (a[0]*b[0])
+ * r[32] holds (b[1]*b[1])
+ */
+
+ c1 = (int)(bn_add_words(t, r, &(r[n2]), n2));
+
+ /* t[32] is negative */
+ c1 -= (int)(bn_sub_words(&(t[n2]), t, &(t[n2]), n2));
+
+ /*-
+ * t[32] holds (a[0]-a[1])*(a[1]-a[0])+(a[0]*a[0])+(a[1]*a[1])
+ * r[10] holds (a[0]*a[0])
+ * r[32] holds (a[1]*a[1])
+ * c1 holds the carry bits
+ */
+ c1 += (int)(bn_add_words(&(r[n]), &(r[n]), &(t[n2]), n2));
+ if (c1) {
+ p = &(r[n + n2]);
+ lo = *p;
+ ln = (lo + c1) & BN_MASK2;
+ *p = ln;
+
+ /*
+ * The overflow will stop before we over write words we should not
+ * overwrite
+ */
+ if (ln < (BN_ULONG)c1) {
+ do {
+ p++;
+ lo = *p;
+ ln = (lo + 1) & BN_MASK2;
+ *p = ln;
+ } while (ln == 0);
+ }
+ }
+}
+#endif