From de8f24ea083384bb66b32ec105dc4743c5663cdf Mon Sep 17 00:00:00 2001
From: beck <>
Date: Wed, 29 Sep 1999 04:37:45 +0000
Subject: OpenSSL 0.9.4 merge

---
 src/lib/libcrypto/bn/bn_div.c | 180 +++++++++++++++++++++++++++++-------------
 1 file changed, 126 insertions(+), 54 deletions(-)

(limited to 'src/lib/libcrypto/bn/bn_div.c')

diff --git a/src/lib/libcrypto/bn/bn_div.c b/src/lib/libcrypto/bn/bn_div.c
index 2263bdc7da..150dd289a5 100644
--- a/src/lib/libcrypto/bn/bn_div.c
+++ b/src/lib/libcrypto/bn/bn_div.c
@@ -57,21 +57,19 @@
  */
 
 #include <stdio.h>
+#include <openssl/bn.h>
 #include "cryptlib.h"
 #include "bn_lcl.h"
 
 /* The old slow way */
 #if 0
-int BN_div(dv, rem, m, d,ctx)
-BIGNUM *dv;
-BIGNUM *rem;
-BIGNUM *m;
-BIGNUM *d;
-BN_CTX *ctx;
+int BN_div(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BIGNUM *d, BN_CTX *ctx)
 	{
 	int i,nm,nd;
 	BIGNUM *D;
 
+	bn_check_top(m);
+	bn_check_top(d);
 	if (BN_is_zero(d))
 		{
 		BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO);
@@ -86,9 +84,9 @@ BN_CTX *ctx;
 		return(1);
 		}
 
-	D=ctx->bn[ctx->tos];
-	if (dv == NULL) dv=ctx->bn[ctx->tos+1];
-	if (rem == NULL) rem=ctx->bn[ctx->tos+2];
+	D= &(ctx->bn[ctx->tos]);
+	if (dv == NULL) dv= &(ctx->bn[ctx->tos+1]);
+	if (rem == NULL) rem= &(ctx->bn[ctx->tos+2]);
 
 	nd=BN_num_bits(d);
 	nm=BN_num_bits(m);
@@ -98,6 +96,7 @@ BN_CTX *ctx;
 	/* The next 2 are needed so we can do a dv->d[0]|=1 later
 	 * since BN_lshift1 will only work once there is a value :-) */
 	BN_zero(dv);
+	bn_wexpand(dv,1);
 	dv->top=1;
 
 	if (!BN_lshift(D,D,nm-nd)) return(0);
@@ -107,7 +106,7 @@ BN_CTX *ctx;
 		if (BN_ucmp(rem,D) >= 0)
 			{
 			dv->d[0]|=1;
-			bn_qsub(rem,rem,D);
+			if (!BN_usub(rem,rem,D)) return(0);
 			}
 /* CAN IMPROVE (and have now :=) */
 		if (!BN_rshift1(D,D)) return(0);
@@ -119,12 +118,8 @@ BN_CTX *ctx;
 
 #else
 
-int BN_div(dv, rm, num, divisor,ctx)
-BIGNUM *dv;
-BIGNUM *rm;
-BIGNUM *num;
-BIGNUM *divisor;
-BN_CTX *ctx;
+int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
+	   BN_CTX *ctx)
 	{
 	int norm_shift,i,j,loop;
 	BIGNUM *tmp,wnum,*snum,*sdiv,*res;
@@ -132,6 +127,9 @@ BN_CTX *ctx;
 	BN_ULONG d0,d1;
 	int num_n,div_n;
 
+	bn_check_top(num);
+	bn_check_top(divisor);
+
 	if (BN_is_zero(divisor))
 		{
 		BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO);
@@ -146,12 +144,12 @@ BN_CTX *ctx;
 		return(1);
 		}
 
-	tmp=ctx->bn[ctx->tos]; 
+	tmp= &(ctx->bn[ctx->tos]);
 	tmp->neg=0;
-	snum=ctx->bn[ctx->tos+1];
-	sdiv=ctx->bn[ctx->tos+2];
+	snum= &(ctx->bn[ctx->tos+1]);
+	sdiv= &(ctx->bn[ctx->tos+2]);
 	if (dv == NULL)
-		res=ctx->bn[ctx->tos+3];
+		res= &(ctx->bn[ctx->tos+3]);
 	else	res=dv;
 
 	/* First we normalise the numbers */
@@ -168,10 +166,10 @@ BN_CTX *ctx;
 	/* Lets setup a 'window' into snum
 	 * This is the part that corresponds to the current
 	 * 'area' being divided */
+	BN_init(&wnum);
 	wnum.d=	 &(snum->d[loop]);
 	wnum.top= div_n;
-	wnum.max= snum->max; /* a bit of a lie */
-	wnum.neg= 0;
+	wnum.max= snum->max+1; /* a bit of a lie */
 
 	/* Get the top 2 words of sdiv */
 	/* i=sdiv->top; */
@@ -183,8 +181,8 @@ BN_CTX *ctx;
 
 	/* Setup to 'res' */
 	res->neg= (num->neg^divisor->neg);
-	res->top=loop;
 	if (!bn_wexpand(res,(loop+1))) goto err;
+	res->top=loop;
 	resp= &(res->d[loop-1]);
 
 	/* space for temp */
@@ -192,7 +190,7 @@ BN_CTX *ctx;
 
 	if (BN_ucmp(&wnum,sdiv) >= 0)
 		{
-		bn_qsub(&wnum,&wnum,sdiv);
+		if (!BN_usub(&wnum,&wnum,sdiv)) goto err;
 		*resp=1;
 		res->d[res->top-1]=1;
 		}
@@ -202,56 +200,98 @@ BN_CTX *ctx;
 
 	for (i=0; i<loop-1; i++)
 		{
-		BN_ULONG q,n0,n1;
-		BN_ULONG l0;
+		BN_ULONG q,l0;
+#ifdef BN_DIV3W
+		q=bn_div_3_words(wnump,d0,d1);
+#else
+
+#if !defined(NO_ASM) && !defined(PEDANTIC)
+# if defined(__GNUC__) && __GNUC__>=2
+#  if defined(__i386)
+   /*
+    * There were two reasons for implementing this template:
+    * - GNU C generates a call to a function (__udivdi3 to be exact)
+    *   in reply to ((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0 (I fail to
+    *   understand why...);
+    * - divl doesn't only calculate quotient, but also leaves
+    *   remainder in %edx which we can definitely use here:-)
+    *
+    *					<appro@fy.chalmers.se>
+    */
+#  define bn_div_words(n0,n1,d0)		\
+	({  asm volatile (			\
+		"divl	%4"			\
+		: "=a"(q), "=d"(rem)		\
+		: "a"(n1), "d"(n0), "g"(d0)	\
+		: "cc");			\
+	    q;					\
+	})
+#  define REMINDER_IS_ALREADY_CALCULATED
+#  endif /* __<cpu> */
+# endif /* __GNUC__ */
+#endif /* NO_ASM */
+		BN_ULONG n0,n1,rem=0;
 
-		wnum.d--; wnum.top++;
 		n0=wnump[0];
 		n1=wnump[-1];
 		if (n0 == d0)
 			q=BN_MASK2;
 		else
-			q=bn_div64(n0,n1,d0);
+#if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)
+			q=((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0;
+#else
+			q=bn_div_words(n0,n1,d0);
+#endif
 		{
 #ifdef BN_LLONG
-		BN_ULLONG t1,t2,rem;
-		t1=((BN_ULLONG)n0<<BN_BITS2)|n1;
+		BN_ULLONG t2;
+
+#ifndef REMINDER_IS_ALREADY_CALCULATED
+		/*
+		 * rem doesn't have to be BN_ULLONG. The least we
+		 * know it's less that d0, isn't it?
+		 */
+		rem=(n1-q*d0)&BN_MASK2;
+#endif
+		t2=(BN_ULLONG)d1*q;
+
 		for (;;)
 			{
-			t2=(BN_ULLONG)d1*q;
-			rem=t1-(BN_ULLONG)q*d0;
-			if ((rem>>BN_BITS2) ||
-				(t2 <= ((BN_ULLONG)(rem<<BN_BITS2)+wnump[-2])))
+                        if (t2 <= ((((BN_ULLONG)rem)<<BN_BITS2)|wnump[-2]))
 				break;
 			q--;
+			rem += d0;
+			if (rem < d0) break; /* don't let rem overflow */
+			t2 -= d1;
 			}
 #else
-		BN_ULONG t1l,t1h,t2l,t2h,t3l,t3h,ql,qh,t3t;
-		t1h=n0;
-		t1l=n1;
+		BN_ULONG t2l,t2h,ql,qh;
+
+#ifndef REMINDER_IS_ALREADY_CALCULATED
+		/*
+		 * It's more than enough with the only multiplication.
+		 * See the comment above in BN_LLONG section...
+		 */
+		rem=(n1-q*d0)&BN_MASK2;
+#endif
+		t2l=LBITS(d1); t2h=HBITS(d1);
+		ql =LBITS(q);  qh =HBITS(q);
+		mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */
+
 		for (;;)
 			{
-			t2l=LBITS(d1); t2h=HBITS(d1);
-			ql =LBITS(q);  qh =HBITS(q);
-			mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */
-
-			t3t=LBITS(d0); t3h=HBITS(d0);
-			mul64(t3t,t3h,ql,qh); /* t3=t1-(BN_ULLONG)q*d0; */
-			t3l=(t1l-t3t)&BN_MASK2;
-			if (t3l > t1l) t3h++;
-			t3h=(t1h-t3h)&BN_MASK2;
-
-			/*if ((t3>>BN_BITS2) ||
-				(t2 <= ((t3<<BN_BITS2)+wnump[-2])))
-				break; */
-			if (t3h) break;
-			if (t2h < t3l) break;
-			if ((t2h == t3l) && (t2l <= wnump[-2])) break;
-
+			if ((t2h < rem) ||
+				((t2h == rem) && (t2l <= wnump[-2])))
+				break;
 			q--;
+			rem += d0;
+			if (rem < d0) break; /* don't let rem overflow */
+			if (t2l < d1) t2h--; t2l -= d1;
 			}
 #endif
 		}
+#endif /* !BN_DIV3W */
+		wnum.d--; wnum.top++;
 		l0=bn_mul_words(tmp->d,sdiv->d,div_n,q);
 		tmp->d[div_n]=l0;
 		for (j=div_n+1; j>0; j--)
@@ -284,3 +324,35 @@ err:
 	}
 
 #endif
+
+/* rem != m */
+int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
+	{
+#if 0 /* The old slow way */
+	int i,nm,nd;
+	BIGNUM *dv;
+
+	if (BN_ucmp(m,d) < 0)
+		return((BN_copy(rem,m) == NULL)?0:1);
+
+	dv= &(ctx->bn[ctx->tos]);
+
+	if (!BN_copy(rem,m)) return(0);
+
+	nm=BN_num_bits(rem);
+	nd=BN_num_bits(d);
+	if (!BN_lshift(dv,d,nm-nd)) return(0);
+	for (i=nm-nd; i>=0; i--)
+		{
+		if (BN_cmp(rem,dv) >= 0)
+			{
+			if (!BN_sub(rem,rem,dv)) return(0);
+			}
+		if (!BN_rshift1(dv,dv)) return(0);
+		}
+	return(1);
+#else
+	return(BN_div(NULL,rem,m,d,ctx));
+#endif
+	}
+
-- 
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