text: /* crypto/bn/bn_div.c */
  /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   * All rights reserved.
   *
   * This package is an SSL implementation written
   * by Eric Young (eay@cryptsoft.com).
   * The implementation was written so as to conform with Netscapes SSL.
   * 
   * This library is free for commercial and non-commercial use as long as
   * the following conditions are aheared to.  The following conditions
   * apply to all code found in this distribution, be it the RC4, RSA,
   * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
   * included with this distribution is covered by the same copyright terms
   * except that the holder is Tim Hudson (tjh@cryptsoft.com).
   * 
   * Copyright remains Eric Young's, and as such any Copyright notices in
   * the code are not to be removed.
   * If this package is used in a product, Eric Young should be given attribution
   * as the author of the parts of the library used.
   * This can be in the form of a textual message at program startup or
   * in documentation (online or textual) provided with the package.
   * 
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *    "This product includes cryptographic software written by
   *     Eric Young (eay@cryptsoft.com)"
   *    The word 'cryptographic' can be left out if the rouines from the library
   *    being used are not cryptographic related :-).
   * 4. If you include any Windows specific code (or a derivative thereof) from 
   *    the apps directory (application code) you must include an acknowledgement:
   *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
   * 
   * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   * 
   * The licence and distribution terms for any publically available version or
   * derivative of this code cannot be changed.  i.e. this code cannot simply be
   * copied and put under another distribution licence
   * [including the GNU Public Licence.]
   */
  
  #include <stdio.h>
  #include <openssl/bn.h>
  #include "cryptlib.h"
  #include "bn_lcl.h"
  
  
  /* The old slow way */
  #if 0
  int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d,
  	   BN_CTX *ctx)
  	{
  	int i,nm,nd;
  	int ret = 0;
  	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);
  		return(0);
  		}
  
  	if (BN_ucmp(m,d) < 0)
  		{
  		if (rem != NULL)
  			{ if (BN_copy(rem,m) == NULL) return(0); }
  		if (dv != NULL) BN_zero(dv);
  		return(1);
  		}
  
  	BN_CTX_start(ctx);
  	D = BN_CTX_get(ctx);
  	if (dv == NULL) dv = BN_CTX_get(ctx);
  	if (rem == NULL) rem = BN_CTX_get(ctx);
  	if (D == NULL || dv == NULL || rem == NULL)
  		goto end;
  
  	nd=BN_num_bits(d);
  	nm=BN_num_bits(m);
  	if (BN_copy(D,d) == NULL) goto end;
  	if (BN_copy(rem,m) == NULL) goto end;
  
  	/* 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);
  	if(bn_wexpand(dv,1) == NULL) goto end;
  	dv->top=1;
  
  	if (!BN_lshift(D,D,nm-nd)) goto end;
  	for (i=nm-nd; i>=0; i--)
  		{
  		if (!BN_lshift1(dv,dv)) goto end;
  		if (BN_ucmp(rem,D) >= 0)
  			{
  			dv->d[0]|=1;
  			if (!BN_usub(rem,rem,D)) goto end;
  			}
  /* CAN IMPROVE (and have now :=) */
  		if (!BN_rshift1(D,D)) goto end;
  		}
  	rem->neg=BN_is_zero(rem)?0:m->neg;
  	dv->neg=m->neg^d->neg;
  	ret = 1;
   end:
  	BN_CTX_end(ctx);
  	return(ret);
  	}
  
  #else
  
  #if !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM) \
      && !defined(PEDANTIC) && !defined(BN_DIV3W)
  # if defined(__GNUC__) && __GNUC__>=2
  #  if defined(__i386) || 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 REMAINDER_IS_ALREADY_CALCULATED
  #  elif defined(__x86_64) && defined(SIXTY_FOUR_BIT_LONG)
     /*
      * Same story here, but it's 128-bit by 64-bit division. Wow!
      *					<appro@fy.chalmers.se>
      */
  #  define bn_div_words(n0,n1,d0)		\
  	({  asm volatile (			\
  		"divq	%4"			\
  		: "=a"(q), "=d"(rem)		\
  		: "a"(n1), "d"(n0), "g"(d0)	\
  		: "cc");			\
  	    q;					\
  	})
  #  define REMAINDER_IS_ALREADY_CALCULATED
  #  endif /* __<cpu> */
  # endif /* __GNUC__ */
  #endif /* OPENSSL_NO_ASM */
  
  
  /* BN_div[_no_branch] computes  dv := num / divisor,  rounding towards
   * zero, and sets up rm  such that  dv*divisor + rm = num  holds.
   * Thus:
   *     dv->neg == num->neg ^ divisor->neg  (unless the result is zero)
   *     rm->neg == num->neg                 (unless the remainder is zero)
   * If 'dv' or 'rm' is NULL, the respective value is not returned.
   */
  static int BN_div_no_branch(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num,
          const 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,loop;
  	BIGNUM *tmp,wnum,*snum,*sdiv,*res;
  	BN_ULONG *resp,*wnump;
  	BN_ULONG d0,d1;
  	int num_n,div_n;
  
  	/* Invalid zero-padding would have particularly bad consequences
  	 * in the case of 'num', so don't just rely on bn_check_top() for this one
  	 * (bn_check_top() works only for BN_DEBUG builds) */
  	if (num->top > 0 && num->d[num->top - 1] == 0)
  		{
  		BNerr(BN_F_BN_DIV,BN_R_NOT_INITIALIZED);
  		return 0;
  		}
  
  	bn_check_top(num);
  
  	if ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0))
  		{
  		return BN_div_no_branch(dv, rm, num, divisor, ctx);
  		}
  
  	bn_check_top(dv);
  	bn_check_top(rm);
  	/* bn_check_top(num); */ /* 'num' has been checked already */
  	bn_check_top(divisor);
  
  	if (BN_is_zero(divisor))
  		{
  		BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO);
  		return(0);
  		}
  
  	if (BN_ucmp(num,divisor) < 0)
  		{
  		if (rm != NULL)
  			{ if (BN_copy(rm,num) == NULL) return(0); }
  		if (dv != NULL) BN_zero(dv);
  		return(1);
  		}
  
  	BN_CTX_start(ctx);
  	tmp=BN_CTX_get(ctx);
  	snum=BN_CTX_get(ctx);
  	sdiv=BN_CTX_get(ctx);
  	if (dv == NULL)
  		res=BN_CTX_get(ctx);
  	else	res=dv;
  	if (sdiv == NULL || res == NULL || tmp == NULL || snum == NULL)
  		goto err;
  
  	/* First we normalise the numbers */
  	norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
  	if (!(BN_lshift(sdiv,divisor,norm_shift))) goto err;
  	sdiv->neg=0;
  	norm_shift+=BN_BITS2;
  	if (!(BN_lshift(snum,num,norm_shift))) goto err;
  	snum->neg=0;
  	div_n=sdiv->top;
  	num_n=snum->top;
  	loop=num_n-div_n;
  	/* Lets setup a 'window' into snum
  	 * This is the part that corresponds to the current
  	 * 'area' being divided */
  	wnum.neg   = 0;
  	wnum.d     = &(snum->d[loop]);
  	wnum.top   = div_n;
  	/* only needed when BN_ucmp messes up the values between top and max */
  	wnum.dmax  = snum->dmax - loop; /* so we don't step out of bounds */
  
  	/* Get the top 2 words of sdiv */
  	/* div_n=sdiv->top; */
  	d0=sdiv->d[div_n-1];
  	d1=(div_n == 1)?0:sdiv->d[div_n-2];
  
  	/* pointer to the 'top' of snum */
  	wnump= &(snum->d[num_n-1]);
  
  	/* Setup to 'res' */
  	res->neg= (num->neg^divisor->neg);
  	if (!bn_wexpand(res,(loop+1))) goto err;
  	res->top=loop;
  	resp= &(res->d[loop-1]);
  
  	/* space for temp */
  	if (!bn_wexpand(tmp,(div_n+1))) goto err;
  
  	if (BN_ucmp(&wnum,sdiv) >= 0)
  		{
  		/* If BN_DEBUG_RAND is defined BN_ucmp changes (via
  		 * bn_pollute) the const bignum arguments =>
  		 * clean the values between top and max again */
  		bn_clear_top2max(&wnum);
  		bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n);
  		*resp=1;
  		}
  	else
  		res->top--;
  	/* if res->top == 0 then clear the neg value otherwise decrease
  	 * the resp pointer */
  	if (res->top == 0)
  		res->neg = 0;
  	else
  		resp--;
  
  	for (i=0; i<loop-1; i++, wnump--, resp--)
  		{
  		BN_ULONG q,l0;
  		/* the first part of the loop uses the top two words of
  		 * snum and sdiv to calculate a BN_ULONG q such that
  		 * | wnum - sdiv * q | < sdiv */
  #if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM)
  		BN_ULONG bn_div_3_words(BN_ULONG*,BN_ULONG,BN_ULONG);
  		q=bn_div_3_words(wnump,d1,d0);
  #else
  		BN_ULONG n0,n1,rem=0;
  
  		n0=wnump[0];
  		n1=wnump[-1];
  		if (n0 == d0)
  			q=BN_MASK2;
  		else 			/* n0 < d0 */
  			{
  #ifdef BN_LLONG
  			BN_ULLONG t2;
  
  #if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)
  			q=(BN_ULONG)(((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0);
  #else
  			q=bn_div_words(n0,n1,d0);
  #ifdef BN_DEBUG_LEVITTE
  			fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
  X) -> 0x%08X\n",
  				n0, n1, d0, q);
  #endif
  #endif
  
  #ifndef REMAINDER_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 (;;)
  				{
  				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_LLONG */
  			BN_ULONG t2l,t2h;
  
  			q=bn_div_words(n0,n1,d0);
  #ifdef BN_DEBUG_LEVITTE
  			fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
  X) -> 0x%08X\n",
  				n0, n1, d0, q);
  #endif
  #ifndef REMAINDER_IS_ALREADY_CALCULATED
  			rem=(n1-q*d0)&BN_MASK2;
  #endif
  
  #if defined(BN_UMULT_LOHI)
  			BN_UMULT_LOHI(t2l,t2h,d1,q);
  #elif defined(BN_UMULT_HIGH)
  			t2l = d1 * q;
  			t2h = BN_UMULT_HIGH(d1,q);
  #else
  			{
  			BN_ULONG ql, qh;
  			t2l=LBITS(d1); t2h=HBITS(d1);
  			ql =LBITS(q);  qh =HBITS(q);
  			mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */
  			}
  #endif
  
  			for (;;)
  				{
  				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 /* !BN_LLONG */
  			}
  #endif /* !BN_DIV3W */
  
  		l0=bn_mul_words(tmp->d,sdiv->d,div_n,q);
  		tmp->d[div_n]=l0;
  		wnum.d--;
  		/* ingore top values of the bignums just sub the two 
  		 * BN_ULONG arrays with bn_sub_words */
  		if (bn_sub_words(wnum.d, wnum.d, tmp->d, div_n+1))
  			{
  			/* Note: As we have considered only the leading
  			 * two BN_ULONGs in the calculation of q, sdiv * q
  			 * might be greater than wnum (but then (q-1) * sdiv
  			 * is less or equal than wnum)
  			 */
  			q--;
  			if (bn_add_words(wnum.d, wnum.d, sdiv->d, div_n))
  				/* we can't have an overflow here (assuming
  				 * that q != 0, but if q == 0 then tmp is
  				 * zero anyway) */
  				(*wnump)++;
  			}
  		/* store part of the result */
  		*resp = q;
  		}
  	bn_correct_top(snum);
  	if (rm != NULL)
  		{
  		/* Keep a copy of the neg flag in num because if rm==num
  		 * BN_rshift() will overwrite it.
  		 */
  		int neg = num->neg;
  		BN_rshift(rm,snum,norm_shift);
  		if (!BN_is_zero(rm))
  			rm->neg = neg;
  		bn_check_top(rm);
  		}
  	BN_CTX_end(ctx);
  	return(1);
  err:
  	bn_check_top(rm);
  	BN_CTX_end(ctx);
  	return(0);
  	}
  
  
  /* BN_div_no_branch is a special version of BN_div. It does not contain
   * branches that may leak sensitive information.
   */
  static int BN_div_no_branch(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, 
  	const BIGNUM *divisor, BN_CTX *ctx)
  	{
  	int norm_shift,i,loop;
  	BIGNUM *tmp,wnum,*snum,*sdiv,*res;
  	BN_ULONG *resp,*wnump;
  	BN_ULONG d0,d1;
  	int num_n,div_n;
  
  	bn_check_top(dv);
  	bn_check_top(rm);
  	/* bn_check_top(num); */ /* 'num' has been checked in BN_div() */
  	bn_check_top(divisor);
  
  	if (BN_is_zero(divisor))
  		{
  		BNerr(BN_F_BN_DIV_NO_BRANCH,BN_R_DIV_BY_ZERO);
  		return(0);
  		}
  
  	BN_CTX_start(ctx);
  	tmp=BN_CTX_get(ctx);
  	snum=BN_CTX_get(ctx);
  	sdiv=BN_CTX_get(ctx);
  	if (dv == NULL)
  		res=BN_CTX_get(ctx);
  	else	res=dv;
  	if (sdiv == NULL || res == NULL) goto err;
  
  	/* First we normalise the numbers */
  	norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
  	if (!(BN_lshift(sdiv,divisor,norm_shift))) goto err;
  	sdiv->neg=0;
  	norm_shift+=BN_BITS2;
  	if (!(BN_lshift(snum,num,norm_shift))) goto err;
  	snum->neg=0;
  
  	/* Since we don't know whether snum is larger than sdiv,
  	 * we pad snum with enough zeroes without changing its
  	 * value. 
  	 */
  	if (snum->top <= sdiv->top+1) 
  		{
  		if (bn_wexpand(snum, sdiv->top + 2) == NULL) goto err;
  		for (i = snum->top; i < sdiv->top + 2; i++) snum->d[i] = 0;
  		snum->top = sdiv->top + 2;
  		}
  	else
  		{
  		if (bn_wexpand(snum, snum->top + 1) == NULL) goto err;
  		snum->d[snum->top] = 0;
  		snum->top ++;
  		}
  
  	div_n=sdiv->top;
  	num_n=snum->top;
  	loop=num_n-div_n;
  	/* Lets setup a 'window' into snum
  	 * This is the part that corresponds to the current
  	 * 'area' being divided */
  	wnum.neg   = 0;
  	wnum.d     = &(snum->d[loop]);
  	wnum.top   = div_n;
  	/* only needed when BN_ucmp messes up the values between top and max */
  	wnum.dmax  = snum->dmax - loop; /* so we don't step out of bounds */
  
  	/* Get the top 2 words of sdiv */
  	/* div_n=sdiv->top; */
  	d0=sdiv->d[div_n-1];
  	d1=(div_n == 1)?0:sdiv->d[div_n-2];
  
  	/* pointer to the 'top' of snum */
  	wnump= &(snum->d[num_n-1]);
  
  	/* Setup to 'res' */
  	res->neg= (num->neg^divisor->neg);
  	if (!bn_wexpand(res,(loop+1))) goto err;
  	res->top=loop-1;
  	resp= &(res->d[loop-1]);
  
  	/* space for temp */
  	if (!bn_wexpand(tmp,(div_n+1))) goto err;
  
  	/* if res->top == 0 then clear the neg value otherwise decrease
  	 * the resp pointer */
  	if (res->top == 0)
  		res->neg = 0;
  	else
  		resp--;
  
  	for (i=0; i<loop-1; i++, wnump--, resp--)
  		{
  		BN_ULONG q,l0;
  		/* the first part of the loop uses the top two words of
  		 * snum and sdiv to calculate a BN_ULONG q such that
  		 * | wnum - sdiv * q | < sdiv */
  #if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM)
  		BN_ULONG bn_div_3_words(BN_ULONG*,BN_ULONG,BN_ULONG);
  		q=bn_div_3_words(wnump,d1,d0);
  #else
  		BN_ULONG n0,n1,rem=0;
  
  		n0=wnump[0];
  		n1=wnump[-1];
  		if (n0 == d0)
  			q=BN_MASK2;
  		else 			/* n0 < d0 */
  			{
  #ifdef BN_LLONG
  			BN_ULLONG t2;
  
  #if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)
  			q=(BN_ULONG)(((((BN_ULLONG)n0)<<BN_BITS2)|n1)/d0);
  #else
  			q=bn_div_words(n0,n1,d0);
  #ifdef BN_DEBUG_LEVITTE
  			fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
  X) -> 0x%08X\n",
  				n0, n1, d0, q);
  #endif
  #endif
  
  #ifndef REMAINDER_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 (;;)
  				{
  				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_LLONG */
  			BN_ULONG t2l,t2h;
  
  			q=bn_div_words(n0,n1,d0);
  #ifdef BN_DEBUG_LEVITTE
  			fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
  X) -> 0x%08X\n",
  				n0, n1, d0, q);
  #endif
  #ifndef REMAINDER_IS_ALREADY_CALCULATED
  			rem=(n1-q*d0)&BN_MASK2;
  #endif
  
  #if defined(BN_UMULT_LOHI)
  			BN_UMULT_LOHI(t2l,t2h,d1,q);
  #elif defined(BN_UMULT_HIGH)
  			t2l = d1 * q;
  			t2h = BN_UMULT_HIGH(d1,q);
  #else
  			{
  			BN_ULONG ql, qh;
  			t2l=LBITS(d1); t2h=HBITS(d1);
  			ql =LBITS(q);  qh =HBITS(q);
  			mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1*q; */
  			}
  #endif
  
  			for (;;)
  				{
  				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 /* !BN_LLONG */
  			}
  #endif /* !BN_DIV3W */
  
  		l0=bn_mul_words(tmp->d,sdiv->d,div_n,q);
  		tmp->d[div_n]=l0;
  		wnum.d--;
  		/* ingore top values of the bignums just sub the two 
  		 * BN_ULONG arrays with bn_sub_words */
  		if (bn_sub_words(wnum.d, wnum.d, tmp->d, div_n+1))
  			{
  			/* Note: As we have considered only the leading
  			 * two BN_ULONGs in the calculation of q, sdiv * q
  			 * might be greater than wnum (but then (q-1) * sdiv
  			 * is less or equal than wnum)
  			 */
  			q--;
  			if (bn_add_words(wnum.d, wnum.d, sdiv->d, div_n))
  				/* we can't have an overflow here (assuming
  				 * that q != 0, but if q == 0 then tmp is
  				 * zero anyway) */
  				(*wnump)++;
  			}
  		/* store part of the result */
  		*resp = q;
  		}
  	bn_correct_top(snum);
  	if (rm != NULL)
  		{
  		/* Keep a copy of the neg flag in num because if rm==num
  		 * BN_rshift() will overwrite it.
  		 */
  		int neg = num->neg;
  		BN_rshift(rm,snum,norm_shift);
  		if (!BN_is_zero(rm))
  			rm->neg = neg;
  		bn_check_top(rm);
  		}
  	bn_correct_top(res);
  	BN_CTX_end(ctx);
  	return(1);
  err:
  	bn_check_top(rm);
  	BN_CTX_end(ctx);
  	return(0);
  	}
  
  #endif
  