Bug fix!
[openssl.git] / crypto / bn / bn_mul.c
index 0af6e96d7aae6ddb675ea480defd7da537d43fb4..eb007e19e9a9063700ca358ab9a61e6cd3bd850e 100644 (file)
  * n2 must be a power of 2.
  * We multiply and return the result.
  * t must be 2*n2 words in size
- * We calulate
+ * 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_mul_recursive(r,a,b,n2,t)
-BN_ULONG *r,*a,*b;
-int n2;
-BN_ULONG *t;
+void bn_mul_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
+            BN_ULONG *t)
        {
        int n=n2/2,c1,c2;
        unsigned int neg,zero;
        BN_ULONG ln,lo,*p;
 
-#ifdef BN_COUNT
-printf(" bn_mul_recursive %d * %d\n",n2,n2);
-#endif
-#ifdef BN_MUL_COMBA
-/*     if (n2 == 4)
+# ifdef BN_COUNT
+       printf(" bn_mul_recursive %d * %d\n",n2,n2);
+# endif
+# ifdef BN_MUL_COMBA
+#  if 0
+       if (n2 == 4)
                {
                bn_mul_comba4(r,a,b);
                return;
                }
-       else */ if (n2 == 8)
+#  endif
+       if (n2 == 8)
                {
                bn_mul_comba8(r,a,b);
                return; 
                }
-#endif
+# endif /* BN_MUL_COMBA */
        if (n2 < BN_MUL_RECURSIVE_SIZE_NORMAL)
                {
                /* This should not happen */
@@ -138,7 +138,7 @@ printf(" bn_mul_recursive %d * %d\n",n2,n2);
                break;
                }
 
-#ifdef BN_MUL_COMBA
+# ifdef BN_MUL_COMBA
        if (n == 4)
                {
                if (!zero)
@@ -160,7 +160,7 @@ printf(" bn_mul_recursive %d * %d\n",n2,n2);
                bn_mul_comba8(&(r[n2]),&(a[n]),&(b[n]));
                }
        else
-#endif
+# endif /* BN_MUL_COMBA */
                {
                p= &(t[n2*2]);
                if (!zero)
@@ -217,18 +217,16 @@ printf(" bn_mul_recursive %d * %d\n",n2,n2);
 
 /* n+tn is the word length
  * t needs to be n*4 is size, as does r */
-void bn_mul_part_recursive(r,a,b,tn,n,t)
-BN_ULONG *r,*a,*b;
-int tn,n;
-BN_ULONG *t;
+void bn_mul_part_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int tn,
+            int n, BN_ULONG *t)
        {
        int i,j,n2=n*2;
-       unsigned int c1;
+       unsigned int c1,c2,neg,zero;
        BN_ULONG ln,lo,*p;
 
-#ifdef BN_COUNT
-printf(" bn_mul_part_recursive %d * %d\n",tn+n,tn+n);
-#endif
+# ifdef BN_COUNT
+       printf(" bn_mul_part_recursive %d * %d\n",tn+n,tn+n);
+# endif
        if (n < 8)
                {
                i=tn+n;
@@ -237,17 +235,54 @@ printf(" bn_mul_part_recursive %d * %d\n",tn+n,tn+n);
                }
 
        /* r=(a[0]-a[1])*(b[1]-b[0]) */
-       bn_sub_words(t,      a,      &(a[n]),n); /* + */
-       bn_sub_words(&(t[n]),b,      &(b[n]),n); /* - */
-
-/*     if (n == 4)
+       c1=bn_cmp_words(a,&(a[n]),n);
+       c2=bn_cmp_words(&(b[n]),b,n);
+       zero=neg=0;
+       switch (c1*3+c2)
+               {
+       case -4:
+               bn_sub_words(t,      &(a[n]),a,      n); /* - */
+               bn_sub_words(&(t[n]),b,      &(b[n]),n); /* - */
+               break;
+       case -3:
+               zero=1;
+               /* break; */
+       case -2:
+               bn_sub_words(t,      &(a[n]),a,      n); /* - */
+               bn_sub_words(&(t[n]),&(b[n]),b,      n); /* + */
+               neg=1;
+               break;
+       case -1:
+       case 0:
+       case 1:
+               zero=1;
+               /* break; */
+       case 2:
+               bn_sub_words(t,      a,      &(a[n]),n); /* + */
+               bn_sub_words(&(t[n]),b,      &(b[n]),n); /* - */
+               neg=1;
+               break;
+       case 3:
+               zero=1;
+               /* break; */
+       case 4:
+               bn_sub_words(t,      a,      &(a[n]),n);
+               bn_sub_words(&(t[n]),&(b[n]),b,      n);
+               break;
+               }
+               /* The zero case isn't yet implemented here. The speedup
+                  would probably be negligible. */
+# if 0
+       if (n == 4)
                {
                bn_mul_comba4(&(t[n2]),t,&(t[n]));
                bn_mul_comba4(r,a,b);
                bn_mul_normal(&(r[n2]),&(a[n]),tn,&(b[n]),tn);
                memset(&(r[n2+tn*2]),0,sizeof(BN_ULONG)*(n2-tn*2));
                }
-       else */ if (n == 8)
+       else
+# endif
+       if (n == 8)
                {
                bn_mul_comba8(&(t[n2]),t,&(t[n]));
                bn_mul_comba8(r,a,b);
@@ -312,7 +347,16 @@ printf(" bn_mul_part_recursive %d * %d\n",tn+n,tn+n);
         */
 
        c1=(int)(bn_add_words(t,r,&(r[n2]),n2));
-       c1-=(int)(bn_sub_words(&(t[n2]),t,&(t[n2]),n2));
+
+       if (neg) /* if t[32] is negative */
+               {
+               c1-=(int)(bn_sub_words(&(t[n2]),t,&(t[n2]),n2));
+               }
+       else
+               {
+               /* Might have a carry */
+               c1+=(int)(bn_add_words(&(t[n2]),&(t[n2]),t,n2));
+               }
 
        /* t[32] holds (a[0]-a[1])*(b[1]-b[0])+(a[0]*b[0])+(a[1]*b[1])
         * r[10] holds (a[0]*b[0])
@@ -344,16 +388,14 @@ printf(" bn_mul_part_recursive %d * %d\n",tn+n,tn+n);
 /* a and b must be the same size, which is n2.
  * r needs to be n2 words and t needs to be n2*2
  */
-void bn_mul_low_recursive(r,a,b,n2,t)
-BN_ULONG *r,*a,*b;
-int n2;
-BN_ULONG *t;
+void bn_mul_low_recursive(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n2,
+            BN_ULONG *t)
        {
        int n=n2/2;
 
-#ifdef BN_COUNT
-printf(" bn_mul_low_recursive %d * %d\n",n2,n2);
-#endif
+# ifdef BN_COUNT
+       printf(" bn_mul_low_recursive %d * %d\n",n2,n2);
+# endif
 
        bn_mul_recursive(r,a,b,n,&(t[0]));
        if (n >= BN_MUL_LOW_RECURSIVE_SIZE_NORMAL)
@@ -377,19 +419,17 @@ printf(" bn_mul_low_recursive %d * %d\n",n2,n2);
  * l is the low words of the output.
  * t needs to be n2*3
  */
-void bn_mul_high(r,a,b,l,n2,t)
-BN_ULONG *r,*a,*b,*l;
-int n2;
-BN_ULONG *t;
+void bn_mul_high(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, BN_ULONG *l, int n2,
+            BN_ULONG *t)
        {
        int i,n;
        int c1,c2;
        int neg,oneg,zero;
        BN_ULONG ll,lc,*lp,*mp;
 
-#ifdef BN_COUNT
-printf(" bn_mul_high %d * %d\n",n2,n2);
-#endif
+# ifdef BN_COUNT
+       printf(" bn_mul_high %d * %d\n",n2,n2);
+# endif
        n=n2/2;
 
        /* Calculate (al-ah)*(bh-bl) */
@@ -432,14 +472,14 @@ printf(" bn_mul_high %d * %d\n",n2,n2);
        oneg=neg;
        /* t[10] = (a[0]-a[1])*(b[1]-b[0]) */
        /* r[10] = (a[1]*b[1]) */
-#ifdef BN_MUL_COMBA
+# ifdef BN_MUL_COMBA
        if (n == 8)
                {
                bn_mul_comba8(&(t[0]),&(r[0]),&(r[n]));
                bn_mul_comba8(r,&(a[n]),&(b[n]));
                }
        else
-#endif
+# endif
                {
                bn_mul_recursive(&(t[0]),&(r[0]),&(r[n]),n,&(t[n2]));
                bn_mul_recursive(r,&(a[n]),&(b[n]),n,&(t[n2]));
@@ -563,21 +603,23 @@ printf(" bn_mul_high %d * %d\n",n2,n2);
                        }
                }
        }
-#endif
+#endif /* BN_RECURSION */
 
-int BN_mul(r,a,b,ctx)
-BIGNUM *r,*a,*b;
-BN_CTX *ctx;
+int BN_mul(BIGNUM *r, BIGNUM *a, BIGNUM *b, BN_CTX *ctx)
        {
        int top,al,bl;
        BIGNUM *rr;
+       int ret = 0;
+#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)
+       int i;
+#endif
 #ifdef BN_RECURSION
        BIGNUM *t;
-       int i,j,k;
+       int j,k;
 #endif
 
 #ifdef BN_COUNT
-printf("BN_mul %d * %d\n",a->top,b->top);
+       printf("BN_mul %d * %d\n",a->top,b->top);
 #endif
 
        bn_check_top(a);
@@ -595,127 +637,107 @@ printf("BN_mul %d * %d\n",a->top,b->top);
                }
        top=al+bl;
 
+       BN_CTX_start(ctx);
        if ((r == a) || (r == b))
-               rr= &(ctx->bn[ctx->tos+1]);
+               {
+               if ((rr = BN_CTX_get(ctx)) == NULL) goto err;
+               }
        else
-               rr=r;
+               rr = r;
 
 #if defined(BN_MUL_COMBA) || defined(BN_RECURSION)
-       if (al == bl)
+       i = al-bl;
+#endif
+#ifdef BN_MUL_COMBA
+       if (i == 0)
                {
-#  ifdef BN_MUL_COMBA
-/*             if (al == 4)
+# if 0
+               if (al == 4)
                        {
-                       if (bn_wexpand(rr,8) == NULL) return(0);
-                       r->top=8;
+                       if (bn_wexpand(rr,8) == NULL) goto err;
+                       rr->top=8;
                        bn_mul_comba4(rr->d,a->d,b->d);
                        goto end;
                        }
-               else */ if (al == 8)
+# endif
+               if (al == 8)
                        {
-                       if (bn_wexpand(rr,16) == NULL) return(0);
-                       r->top=16;
+                       if (bn_wexpand(rr,16) == NULL) goto err;
+                       rr->top=16;
                        bn_mul_comba8(rr->d,a->d,b->d);
                        goto end;
                        }
-               else
-#  endif
-#ifdef BN_RECURSION
-               if (al < BN_MULL_SIZE_NORMAL)
-#endif
-                       {
-                       if (bn_wexpand(rr,top) == NULL) return(0);
-                       rr->top=top;
-                       bn_mul_normal(rr->d,a->d,al,b->d,bl);
-                       goto end;
-                       }
-#  ifdef BN_RECURSION
-               goto symetric;
-#  endif
                }
-#endif
+#endif /* BN_MUL_COMBA */
 #ifdef BN_RECURSION
-       else if ((al < BN_MULL_SIZE_NORMAL) || (bl < BN_MULL_SIZE_NORMAL))
+       if ((al >= BN_MULL_SIZE_NORMAL) && (bl >= BN_MULL_SIZE_NORMAL))
                {
-               if (bn_wexpand(rr,top) == NULL) return(0);
-               rr->top=top;
-               bn_mul_normal(rr->d,a->d,al,b->d,bl);
-               goto end;
-               }
-       else
-               {
-               i=(al-bl);
-               if ((i ==  1) && !BN_get_flags(b,BN_FLG_STATIC_DATA))
+               if (i == 1 && !BN_get_flags(b,BN_FLG_STATIC_DATA))
                        {
                        bn_wexpand(b,al);
                        b->d[bl]=0;
                        bl++;
-                       goto symetric;
+                       i--;
                        }
-               else if ((i ==  -1) && !BN_get_flags(a,BN_FLG_STATIC_DATA))
+               else if (i == -1 && !BN_get_flags(a,BN_FLG_STATIC_DATA))
                        {
                        bn_wexpand(a,bl);
                        a->d[al]=0;
                        al++;
-                       goto symetric;
+                       i++;
+                       }
+               if (i == 0)
+                       {
+                       /* symmetric and > 4 */
+                       /* 16 or larger */
+                       j=BN_num_bits_word((BN_ULONG)al);
+                       j=1<<(j-1);
+                       k=j+j;
+                       t = BN_CTX_get(ctx);
+                       if (al == j) /* exact multiple */
+                               {
+                               bn_wexpand(t,k*2);
+                               bn_wexpand(rr,k*2);
+                               bn_mul_recursive(rr->d,a->d,b->d,al,t->d);
+                               }
+                       else
+                               {
+                               bn_wexpand(a,k);
+                               bn_wexpand(b,k);
+                               bn_wexpand(t,k*4);
+                               bn_wexpand(rr,k*4);
+                               for (i=a->top; i<k; i++)
+                                       a->d[i]=0;
+                               for (i=b->top; i<k; i++)
+                                       b->d[i]=0;
+                               bn_mul_part_recursive(rr->d,a->d,b->d,al-j,j,t->d);
+                               }
+                       rr->top=top;
+                       goto end;
                        }
                }
-#endif
-
-       /* asymetric and >= 4 */ 
-       if (bn_wexpand(rr,top) == NULL) return(0);
+#endif /* BN_RECURSION */
+       if (bn_wexpand(rr,top) == NULL) goto err;
        rr->top=top;
        bn_mul_normal(rr->d,a->d,al,b->d,bl);
 
-#ifdef BN_RECURSION
-       if (0)
-               {
-symetric:
-               /* symetric and > 4 */
-               /* 16 or larger */
-               j=BN_num_bits_word((BN_ULONG)al);
-               j=1<<(j-1);
-               k=j+j;
-               t= &(ctx->bn[ctx->tos]);
-               if (al == j) /* exact multiple */
-                       {
-                       bn_wexpand(t,k*2);
-                       bn_wexpand(rr,k*2);
-                       bn_mul_recursive(rr->d,a->d,b->d,al,t->d);
-                       }
-               else
-                       {
-                       bn_wexpand(a,k);
-                       bn_wexpand(b,k);
-                       bn_wexpand(t,k*4);
-                       bn_wexpand(rr,k*4);
-                       for (i=a->top; i<k; i++)
-                               a->d[i]=0;
-                       for (i=b->top; i<k; i++)
-                               b->d[i]=0;
-                       bn_mul_part_recursive(rr->d,a->d,b->d,al-j,j,t->d);
-                       }
-               rr->top=top;
-               }
-#endif
 #if defined(BN_MUL_COMBA) || defined(BN_RECURSION)
 end:
 #endif
        bn_fix_top(rr);
        if (r != rr) BN_copy(r,rr);
-       return(1);
+       ret=1;
+err:
+       BN_CTX_end(ctx);
+       return(ret);
        }
 
-void bn_mul_normal(r,a,na,b,nb)
-BN_ULONG *r,*a;
-int na;
-BN_ULONG *b;
-int nb;
+void bn_mul_normal(BN_ULONG *r, BN_ULONG *a, int na, BN_ULONG *b, int nb)
        {
        BN_ULONG *rr;
 
 #ifdef BN_COUNT
-printf(" bn_mul_normal %d * %d\n",na,nb);
+       printf(" bn_mul_normal %d * %d\n",na,nb);
 #endif
 
        if (na < nb)
@@ -746,12 +768,10 @@ printf(" bn_mul_normal %d * %d\n",na,nb);
                }
        }
 
-void bn_mul_low_normal(r,a,b,n)
-BN_ULONG *r,*a,*b;
-int n;
+void bn_mul_low_normal(BN_ULONG *r, BN_ULONG *a, BN_ULONG *b, int n)
        {
 #ifdef BN_COUNT
-printf(" bn_mul_low_normal %d * %d\n",n,n);
+       printf(" bn_mul_low_normal %d * %d\n",n,n);
 #endif
        bn_mul_words(r,a,n,b[0]);
 
@@ -769,4 +789,3 @@ printf(" bn_mul_low_normal %d * %d\n",n,n);
                b+=4;
                }
        }
-