+ int n=n2/2,c1,c2;
+ int tna=n+dna, tnb=n+dnb;
+ unsigned int neg,zero;
+ BN_ULONG ln,lo,*p;
+
+# ifdef BN_COUNT
+ fprintf(stderr," bn_mul_recursive %d%+d * %d%+d\n",n2,dna,n2,dnb);
+# endif
+# ifdef BN_MUL_COMBA
+# if 0
+ if (n2 == 4)
+ {
+ bn_mul_comba4(r,a,b);
+ return;
+ }
+# endif
+ /* Only call bn_mul_comba 8 if n2 == 8 and the
+ * two arrays are complete [steve]
+ */
+ if (n2 == 8 && dna == 0 && dnb == 0)
+ {
+ bn_mul_comba8(r,a,b);
+ return;
+ }
+# endif /* BN_MUL_COMBA */
+ /* Else do normal multiply */
+ if (n2 < BN_MUL_RECURSIVE_SIZE_NORMAL)
+ {
+ bn_mul_normal(r,a,n2+dna,b,n2+dnb);
+ if ((dna + dnb) < 0)
+ memset(&r[2*n2 + dna + dnb], 0,
+ sizeof(BN_ULONG) * -(dna + dnb));
+ return;
+ }
+ /* r=(a[0]-a[1])*(b[1]-b[0]) */
+ c1=bn_cmp_part_words(a,&(a[n]),tna,n-tna);
+ c2=bn_cmp_part_words(&(b[n]),b,tnb,tnb-n);
+ zero=neg=0;
+ switch (c1*3+c2)
+ {
+ case -4:
+ bn_sub_part_words(t, &(a[n]),a, tna,tna-n); /* - */
+ bn_sub_part_words(&(t[n]),b, &(b[n]),tnb,n-tnb); /* - */
+ break;
+ case -3:
+ zero=1;
+ break;
+ case -2:
+ bn_sub_part_words(t, &(a[n]),a, tna,tna-n); /* - */
+ bn_sub_part_words(&(t[n]),&(b[n]),b, tnb,tnb-n); /* + */
+ neg=1;
+ break;
+ case -1:
+ case 0:
+ case 1:
+ zero=1;
+ break;
+ case 2:
+ bn_sub_part_words(t, a, &(a[n]),tna,n-tna); /* + */
+ bn_sub_part_words(&(t[n]),b, &(b[n]),tnb,n-tnb); /* - */
+ neg=1;
+ break;
+ case 3:
+ zero=1;
+ break;
+ case 4:
+ bn_sub_part_words(t, a, &(a[n]),tna,n-tna);
+ bn_sub_part_words(&(t[n]),&(b[n]),b, tnb,tnb-n);
+ break;
+ }
+
+# ifdef BN_MUL_COMBA
+ if (n == 4 && dna == 0 && dnb == 0) /* XXX: bn_mul_comba4 could take
+ extra args to do this well */
+ {
+ if (!zero)
+ bn_mul_comba4(&(t[n2]),t,&(t[n]));
+ else
+ memset(&(t[n2]),0,8*sizeof(BN_ULONG));
+
+ bn_mul_comba4(r,a,b);
+ bn_mul_comba4(&(r[n2]),&(a[n]),&(b[n]));
+ }
+ else if (n == 8 && dna == 0 && dnb == 0) /* XXX: bn_mul_comba8 could
+ take extra args to do this
+ well */
+ {
+ if (!zero)
+ bn_mul_comba8(&(t[n2]),t,&(t[n]));
+ else
+ memset(&(t[n2]),0,16*sizeof(BN_ULONG));
+
+ bn_mul_comba8(r,a,b);
+ bn_mul_comba8(&(r[n2]),&(a[n]),&(b[n]));
+ }
+ else
+# endif /* BN_MUL_COMBA */
+ {
+ p= &(t[n2*2]);
+ if (!zero)
+ bn_mul_recursive(&(t[n2]),t,&(t[n]),n,0,0,p);
+ else
+ memset(&(t[n2]),0,n2*sizeof(BN_ULONG));
+ bn_mul_recursive(r,a,b,n,0,0,p);
+ bn_mul_recursive(&(r[n2]),&(a[n]),&(b[n]),n,dna,dnb,p);
+ }