X-Git-Url: https://git.openssl.org/gitweb/?a=blobdiff_plain;f=crypto%2Fbn%2Fbn_add.c;h=9405163706aae5dc8064780a2ce879fece80ccdf;hb=4407700c40f766cedccc26479d18ff2e8bc19ff4;hp=ecdb7453b5bced26c644d21b7622334f1004dec3;hpb=b7896b3cb86d80206af14a14d69b0717786f2729;p=openssl.git

diff --git a/crypto/bn/bn_add.c b/crypto/bn/bn_add.c
index ecdb7453b5..9405163706 100644
--- a/crypto/bn/bn_add.c
+++ b/crypto/bn/bn_add.c
@@ -1,5 +1,5 @@
 /* crypto/bn/bn_add.c */
-/* Copyright (C) 1995-1997 Eric Young (eay@cryptsoft.com)
+/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
  * This package is an SSL implementation written
@@ -61,110 +61,253 @@
 #include "bn_lcl.h"
 
 /* r can == a or b */
-int BN_add(r, a, b)
-BIGNUM *r;
-BIGNUM *a;
-BIGNUM *b;
+int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
 	{
-	int i;
-	BIGNUM *tmp;
+	const BIGNUM *tmp;
+	int a_neg = a->neg, ret;
+
+	bn_check_top(a);
+	bn_check_top(b);
 
 	/*  a +  b	a+b
 	 *  a + -b	a-b
 	 * -a +  b	b-a
 	 * -a + -b	-(a+b)
 	 */
-	if (a->neg ^ b->neg)
+	if (a_neg ^ b->neg)
 		{
 		/* only one is negative */
-		if (a->neg)
+		if (a_neg)
 			{ tmp=a; a=b; b=tmp; }
 
 		/* we are now a - b */
-		if (bn_expand(r,((a->top > b->top)?a->top:b->top)*BN_BITS2)
-			== NULL) return(0);
 
 		if (BN_ucmp(a,b) < 0)
 			{
-			bn_qsub(r,b,a);
+			if (!BN_usub(r,b,a)) return(0);
 			r->neg=1;
 			}
 		else
 			{
-			bn_qsub(r,a,b);
+			if (!BN_usub(r,a,b)) return(0);
 			r->neg=0;
 			}
 		return(1);
 		}
 
-	if (a->neg) /* both are neg */
-		r->neg=1;
-	else
-		r->neg=0;
-
-	i=(a->top > b->top);
-	if (bn_expand(r,(((i)?a->top:b->top)+1)*BN_BITS2) == NULL) return(0);
-
-	if (i)
-		bn_qadd(r,a,b);
-	else
-		bn_qadd(r,b,a);
-	return(1);
+	ret = BN_uadd(r,a,b);
+	r->neg = a_neg;
+	bn_check_top(r);
+	return ret;
 	}
 
-/* unsigned add of b to a, r must be large enough */
-void bn_qadd(r,a,b)
-BIGNUM *r;
-BIGNUM *a;
-BIGNUM *b;
+/* unsigned add of b to a */
+int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
 	{
-	register int i;
-	int max,min;
+	int max,min,dif;
 	BN_ULONG *ap,*bp,*rp,carry,t1,t2;
+	const BIGNUM *tmp;
+
+	bn_check_top(a);
+	bn_check_top(b);
+
+	if (a->top < b->top)
+		{ tmp=a; a=b; b=tmp; }
+	max = a->top;
+	min = b->top;
+	dif = max - min;
+
+	if (bn_wexpand(r,max+1) == NULL)
+		return 0;
 
-	max=a->top;
-	min=b->top;
 	r->top=max;
 
+
+	ap=a->d;
+	bp=b->d;
+	rp=r->d;
+
+	carry=bn_add_words(rp,ap,bp,min);
+	rp+=min;
+	ap+=min;
+	bp+=min;
+
+	if (carry)
+		{
+		while (dif)
+			{
+			dif--;
+			t1 = *(ap++);
+			t2 = (t1+1) & BN_MASK2;
+			*(rp++) = t2;
+			if (t2)
+				{
+				carry=0;
+				break;
+				}
+			}
+		if (carry)
+			{
+			/* carry != 0 => dif == 0 */
+			*rp = 1;
+			r->top++;
+			}
+		}
+	if (dif && rp != ap)
+		while (dif--)
+			/* copy remaining words if ap != rp */
+			*(rp++) = *(ap++);
+	r->neg = 0;
+	bn_check_top(r);
+	return 1;
+	}
+
+/* unsigned subtraction of b from a, a must be larger than b. */
+int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
+	{
+	int max,min,dif;
+	register BN_ULONG t1,t2,*ap,*bp,*rp;
+	int i,carry;
+#if defined(IRIX_CC_BUG) && !defined(LINT)
+	int dummy;
+#endif
+
+	bn_check_top(a);
+	bn_check_top(b);
+
+	max = a->top;
+	min = b->top;
+	dif = max - min;
+
+	if (dif < 0)	/* hmm... should not be happening */
+		{
+		BNerr(BN_F_BN_USUB,BN_R_ARG2_LT_ARG3);
+		return(0);
+		}
+
+	if (bn_wexpand(r,max) == NULL) return(0);
+
 	ap=a->d;
 	bp=b->d;
 	rp=r->d;
+
+#if 1
 	carry=0;
-	for (i=0; i<min; i++)
+	for (i = min; i != 0; i--)
 		{
 		t1= *(ap++);
 		t2= *(bp++);
 		if (carry)
 			{
-			carry=(t2 >= ((~t1)&BN_MASK2));
-			t2=(t1+t2+1)&BN_MASK2;
+			carry=(t1 <= t2);
+			t1=(t1-t2-1)&BN_MASK2;
 			}
 		else
 			{
-			t2=(t1+t2)&BN_MASK2;
-			carry=(t2 < t1);
+			carry=(t1 < t2);
+			t1=(t1-t2)&BN_MASK2;
 			}
-		*(rp++)=t2;
+#if defined(IRIX_CC_BUG) && !defined(LINT)
+		dummy=t1;
+#endif
+		*(rp++)=t1&BN_MASK2;
 		}
-	if (carry)
+#else
+	carry=bn_sub_words(rp,ap,bp,min);
+	ap+=min;
+	bp+=min;
+	rp+=min;
+#endif
+	if (carry) /* subtracted */
 		{
-		while (i < max)
+		if (!dif)
+			/* error: a < b */
+			return 0;
+		while (dif)
 			{
-			t1= *(ap++);
-			t2=(t1+1)&BN_MASK2;
-			*(rp++)=t2;
-			carry=(t2 < t1);
-			i++;
-			if (!carry) break;
+			dif--;
+			t1 = *(ap++);
+			t2 = (t1-1)&BN_MASK2;
+			*(rp++) = t2;
+			if (t1)
+				break;
 			}
-		if ((i >= max) && carry)
+		}
+#if 0
+	memcpy(rp,ap,sizeof(*rp)*(max-i));
+#else
+	if (rp != ap)
+		{
+		for (;;)
 			{
-			*(rp++)=1;
-			r->top++;
+			if (!dif--) break;
+			rp[0]=ap[0];
+			if (!dif--) break;
+			rp[1]=ap[1];
+			if (!dif--) break;
+			rp[2]=ap[2];
+			if (!dif--) break;
+			rp[3]=ap[3];
+			rp+=4;
+			ap+=4;
 			}
 		}
-	for (; i<max; i++)
-		*(rp++)= *(ap++);
-	/* memcpy(rp,ap,sizeof(*ap)*(max-i));*/
+#endif
+
+	r->top=max;
+	r->neg=0;
+	bn_correct_top(r);
+	return(1);
+	}
+
+int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
+	{
+	int max;
+	int add=0,neg=0;
+	const BIGNUM *tmp;
+
+	bn_check_top(a);
+	bn_check_top(b);
+
+	/*  a -  b	a-b
+	 *  a - -b	a+b
+	 * -a -  b	-(a+b)
+	 * -a - -b	b-a
+	 */
+	if (a->neg)
+		{
+		if (b->neg)
+			{ tmp=a; a=b; b=tmp; }
+		else
+			{ add=1; neg=1; }
+		}
+	else
+		{
+		if (b->neg) { add=1; neg=0; }
+		}
+
+	if (add)
+		{
+		if (!BN_uadd(r,a,b)) return(0);
+		r->neg=neg;
+		return(1);
+		}
+
+	/* We are actually doing a - b :-) */
+
+	max=(a->top > b->top)?a->top:b->top;
+	if (bn_wexpand(r,max) == NULL) return(0);
+	if (BN_ucmp(a,b) < 0)
+		{
+		if (!BN_usub(r,b,a)) return(0);
+		r->neg=1;
+		}
+	else
+		{
+		if (!BN_usub(r,a,b)) return(0);
+		r->neg=0;
+		}
+	bn_check_top(r);
+	return(1);
 	}