Head

GCC Code Coverage Report

Directory:	./		Exec	Total	Coverage
File:	lib/libcrypto/bn/bn_div.c	Lines:	100	107	93.5 %
Date:	2017-11-13	Branches:	82	98	83.7 %


/* $OpenBSD: bn_div.c,v 1.25 2017/01/29 17:49:22 beck Exp $ */
/* 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/opensslconf.h>

#include <openssl/bn.h>
#include <openssl/err.h>

#include "bn_lcl.h"

#if !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM) \
    && !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>
    */
#undef bn_div_words
#  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)
   /*
    * Same story here, but it's 128-bit by 64-bit division. Wow!
    *					<appro@fy.chalmers.se>
    */
#  undef bn_div_words
#  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 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_internal(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
    BN_CTX *ctx, int ct)
{
	int norm_shift, i, loop;
	BIGNUM *tmp, wnum, *snum, *sdiv, *res;
	BN_ULONG *resp, *wnump;
	BN_ULONG d0, d1;
	int num_n, div_n;
	int no_branch = 0;

	/* 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) {
		BNerror(BN_R_NOT_INITIALIZED);
		return 0;
	}

	bn_check_top(num);

	if (ct)
		no_branch = 1;

	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)) {
		BNerror(BN_R_DIV_BY_ZERO);
		return (0);
	}

	if (!no_branch && 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 (tmp == NULL || snum == NULL || 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;

	if (no_branch) {
		/* 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 */
	wnum.flags = snum->flags | BN_FLG_STATIC_DATA;

	/* 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 - no_branch;
	resp = &(res->d[loop - 1]);

	/* space for temp */
	if (!bn_wexpand(tmp, (div_n + 1)))
		goto err;

	if (!no_branch) {
		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_DIV2W) && !defined(bn_div_words)
			q = (BN_ULONG)(((((BN_ULLONG)n0) << BN_BITS2)|n1)/d0);
#else
			q = bn_div_words(n0, n1, d0);
#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);
#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);
	}
	if (no_branch)
		bn_correct_top(res);
	BN_CTX_end(ctx);
	return (1);

err:
	bn_check_top(rm);
	BN_CTX_end(ctx);
	return (0);
}

int
BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
    BN_CTX *ctx)
{
	int ct = ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) ||
	    (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0));

	return BN_div_internal(dv, rm, num, divisor, ctx, ct);
}

int
BN_div_nonct(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
    BN_CTX *ctx)
{
	return BN_div_internal(dv, rm, num, divisor, ctx, 0);
}

int
BN_div_ct(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
    BN_CTX *ctx)
{
	return BN_div_internal(dv, rm, num, divisor, ctx, 1);
}


Generated by: GCOVR (Version 3.3)

Line	Branch	Exec	Source
1			/* $OpenBSD: bn_div.c,v 1.25 2017/01/29 17:49:22 beck Exp $ */
2			/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3			* All rights reserved.
4			*
5			* This package is an SSL implementation written
6			* by Eric Young (eay@cryptsoft.com).
7			* The implementation was written so as to conform with Netscapes SSL.
8			*
9			* This library is free for commercial and non-commercial use as long as
10			* the following conditions are aheared to. The following conditions
11			* apply to all code found in this distribution, be it the RC4, RSA,
12			* lhash, DES, etc., code; not just the SSL code. The SSL documentation
13			* included with this distribution is covered by the same copyright terms
14			* except that the holder is Tim Hudson (tjh@cryptsoft.com).
15			*
16			* Copyright remains Eric Young's, and as such any Copyright notices in
17			* the code are not to be removed.
18			* If this package is used in a product, Eric Young should be given attribution
19			* as the author of the parts of the library used.
20			* This can be in the form of a textual message at program startup or
21			* in documentation (online or textual) provided with the package.
22			*
23			* Redistribution and use in source and binary forms, with or without
24			* modification, are permitted provided that the following conditions
25			* are met:
26			* 1. Redistributions of source code must retain the copyright
27			* notice, this list of conditions and the following disclaimer.
28			* 2. Redistributions in binary form must reproduce the above copyright
29			* notice, this list of conditions and the following disclaimer in the
30			* documentation and/or other materials provided with the distribution.
31			* 3. All advertising materials mentioning features or use of this software
32			* must display the following acknowledgement:
33			* "This product includes cryptographic software written by
34			* Eric Young (eay@cryptsoft.com)"
35			* The word 'cryptographic' can be left out if the rouines from the library
36			* being used are not cryptographic related :-).
37			* 4. If you include any Windows specific code (or a derivative thereof) from
38			* the apps directory (application code) you must include an acknowledgement:
39			* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40			*
41			* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42			* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43			* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44			* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45			* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46			* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47			* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48			* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49			* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50			* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51			* SUCH DAMAGE.
52			*
53			* The licence and distribution terms for any publically available version or
54			* derivative of this code cannot be changed. i.e. this code cannot simply be
55			* copied and put under another distribution licence
56			* [including the GNU Public Licence.]
57			*/
58
59			#include <stdio.h>
60
61			#include <openssl/opensslconf.h>
62
63			#include <openssl/bn.h>
64			#include <openssl/err.h>
65
66			#include "bn_lcl.h"
67
68			#if !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM) \
69			&& !defined(BN_DIV3W)
70			# if defined(__GNUC__) && __GNUC__>=2
71			# if defined(__i386) \|\| defined (__i386__)
72			/*
73			* There were two reasons for implementing this template:
74			* - GNU C generates a call to a function (__udivdi3 to be exact)
75			* in reply to ((((BN_ULLONG)n0)<<BN_BITS2)\|n1)/d0 (I fail to
76			* understand why...);
77			* - divl doesn't only calculate quotient, but also leaves
78			* remainder in %edx which we can definitely use here:-)
79			*
80			* <appro@fy.chalmers.se>
81			*/
82			#undef bn_div_words
83			# define bn_div_words(n0,n1,d0) \
84			({ asm volatile ( \
85			"divl %4" \
86			: "=a"(q), "=d"(rem) \
87			: "a"(n1), "d"(n0), "g"(d0) \
88			: "cc"); \
89			q; \
90			})
91			# define REMAINDER_IS_ALREADY_CALCULATED
92			# elif defined(__x86_64)
93			/*
94			* Same story here, but it's 128-bit by 64-bit division. Wow!
95			* <appro@fy.chalmers.se>
96			*/
97			# undef bn_div_words
98			# define bn_div_words(n0,n1,d0) \
99			({ asm volatile ( \
100			"divq %4" \
101			: "=a"(q), "=d"(rem) \
102			: "a"(n1), "d"(n0), "g"(d0) \
103			: "cc"); \
104			q; \
105			})
106			# define REMAINDER_IS_ALREADY_CALCULATED
107			# endif /* __<cpu> */
108			# endif /* __GNUC__ */
109			#endif /* OPENSSL_NO_ASM */
110
111
112			/* BN_div computes dv := num / divisor, rounding towards
113			* zero, and sets up rm such that dv*divisor + rm = num holds.
114			* Thus:
115			* dv->neg == num->neg ^ divisor->neg (unless the result is zero)
116			* rm->neg == num->neg (unless the remainder is zero)
117			* If 'dv' or 'rm' is NULL, the respective value is not returned.
118			*/
119			static int
120			BN_div_internal(BIGNUM dv, BIGNUM rm, const BIGNUM num, const BIGNUM divisor,
121			BN_CTX *ctx, int ct)
122			{
123			int norm_shift, i, loop;
124		8687792	BIGNUM tmp, wnum, snum, sdiv, res;
125			BN_ULONG resp, wnump;
126			BN_ULONG d0, d1;
127			int num_n, div_n;
128			int no_branch = 0;
129
130			/* Invalid zero-padding would have particularly bad consequences
131			* in the case of 'num', so don't just rely on bn_check_top() for this one
132			* (bn_check_top() works only for BN_DEBUG builds) */
133	✓✓✗✓	8662883	if (num->top > 0 && num->d[num->top - 1] == 0) {
134			BNerror(BN_R_NOT_INITIALIZED);
135			return 0;
136			}
137
138			bn_check_top(num);
139
140	✓✓	4343896	if (ct)
141		4268991	no_branch = 1;
142
143			bn_check_top(dv);
144			bn_check_top(rm);
145			/* bn_check_top(num); / / 'num' has been checked already */
146			bn_check_top(divisor);
147
148	✓✓	4343896	if (BN_is_zero(divisor)) {
149		18	BNerror(BN_R_DIV_BY_ZERO);
150		18	return (0);
151			}
152
153	✓✓✓✓	4418780	if (!no_branch && BN_ucmp(num, divisor) < 0) {
154	✓✓	5433	if (rm != NULL) {
155	✗✓	1659	if (BN_copy(rm, num) == NULL)
156			return (0);
157			}
158	✓✓	5433	if (dv != NULL)
159		4331	BN_zero(dv);
160		5433	return (1);
161			}
162
163		4338445	BN_CTX_start(ctx);
164		4338445	tmp = BN_CTX_get(ctx);
165		4338445	snum = BN_CTX_get(ctx);
166		4338445	sdiv = BN_CTX_get(ctx);
167	✓✓	4338445	if (dv == NULL)
168		634107	res = BN_CTX_get(ctx);
169			else
170			res = dv;
171	✓✗	4338445	if (tmp == NULL \|\| snum == NULL \|\| sdiv == NULL \|\| res == NULL)
172			goto err;
173
174			/* First we normalise the numbers */
175		4338445	norm_shift = BN_BITS2 - ((BN_num_bits(divisor)) % BN_BITS2);
176	✓✗	4338445	if (!(BN_lshift(sdiv, divisor, norm_shift)))
177			goto err;
178		4338445	sdiv->neg = 0;
179		4338445	norm_shift += BN_BITS2;
180	✓✗	4338445	if (!(BN_lshift(snum, num, norm_shift)))
181			goto err;
182		4338445	snum->neg = 0;
183
184	✓✓	4338445	if (no_branch) {
185			/* Since we don't know whether snum is larger than sdiv,
186			* we pad snum with enough zeroes without changing its
187			* value.
188			*/
189	✓✓	4268976	if (snum->top <= sdiv->top + 1) {
190	✓✓✓✗	1687573	if (bn_wexpand(snum, sdiv->top + 2) == NULL)
191			goto err;
192	✓✓	4870044	for (i = snum->top; i < sdiv->top + 2; i++)
193		1591266	snum->d[i] = 0;
194		843756	snum->top = sdiv->top + 2;
195		843756	} else {
196	✓✓✓✗	6858615	if (bn_wexpand(snum, snum->top + 1) == NULL)
197			goto err;
198		3425220	snum->d[snum->top] = 0;
199		3425220	snum->top ++;
200			}
201			}
202
203		4338445	div_n = sdiv->top;
204		4338445	num_n = snum->top;
205		4338445	loop = num_n - div_n;
206			/* Lets setup a 'window' into snum
207			* This is the part that corresponds to the current
208			* 'area' being divided */
209		4338445	wnum.neg = 0;
210		4338445	wnum.d = &(snum->d[loop]);
211		4338445	wnum.top = div_n;
212			/* only needed when BN_ucmp messes up the values between top and max */
213		4338445	wnum.dmax = snum->dmax - loop; /* so we don't step out of bounds */
214		4338445	wnum.flags = snum->flags \| BN_FLG_STATIC_DATA;
215
216			/* Get the top 2 words of sdiv */
217			/* div_n=sdiv->top; */
218		4338445	d0 = sdiv->d[div_n - 1];
219	✓✓	11476273	d1 = (div_n == 1) ? 0 : sdiv->d[div_n - 2];
220
221			/* pointer to the 'top' of snum */
222		4338445	wnump = &(snum->d[num_n - 1]);
223
224			/* Setup to 'res' */
225		4338445	res->neg = (num->neg ^ divisor->neg);
226	✓✓✓✗ ✓✗	8676890	if (!bn_wexpand(res, (loop + 1)))
227			goto err;
228		4338445	res->top = loop - no_branch;
229		4338445	resp = &(res->d[loop - 1]);
230
231			/* space for temp */
232	✓✓✓✗ ✓✗	8676890	if (!bn_wexpand(tmp, (div_n + 1)))
233			goto err;
234
235	✓✓	4338445	if (!no_branch) {
236	✓✓	69469	if (BN_ucmp(&wnum, sdiv) >= 0) {
237			/* If BN_DEBUG_RAND is defined BN_ucmp changes (via
238			* bn_pollute) the const bignum arguments =>
239			* clean the values between top and max again */
240			bn_clear_top2max(&wnum);
241		1331	bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n);
242		1331	*resp = 1;
243		1331	} else
244		68138	res->top--;
245			}
246
247			/* if res->top == 0 then clear the neg value otherwise decrease
248			* the resp pointer */
249	✗✓	4338445	if (res->top == 0)
250			res->neg = 0;
251			else
252		4338445	resp--;
253
254	✓✓	37141508	for (i = 0; i < loop - 1; i++, wnump--, resp--) {
255			BN_ULONG q, l0;
256			/* the first part of the loop uses the top two words of
257			* snum and sdiv to calculate a BN_ULONG q such that
258			* \| wnum - sdiv * q \| < sdiv */
259			#if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM)
260			BN_ULONG bn_div_3_words(BN_ULONG*, BN_ULONG, BN_ULONG);
261			q = bn_div_3_words(wnump, d1, d0);
262			#else
263			BN_ULONG n0, n1, rem = 0;
264
265		14232309	n0 = wnump[0];
266		14232309	n1 = wnump[-1];
267	✓✓	14232309	if (n0 == d0)
268		758	q = BN_MASK2;
269			else /* n0 < d0 */
270			{
271			#ifdef BN_LLONG
272			BN_ULLONG t2;
273
274			#if defined(BN_DIV2W) && !defined(bn_div_words)
275			q = (BN_ULONG)(((((BN_ULLONG)n0) << BN_BITS2)\|n1)/d0);
276			#else
277			q = bn_div_words(n0, n1, d0);
278			#endif
279
280			#ifndef REMAINDER_IS_ALREADY_CALCULATED
281			/*
282			* rem doesn't have to be BN_ULLONG. The least we
283			* know it's less that d0, isn't it?
284			*/
285			rem = (n1 - q * d0) & BN_MASK2;
286			#endif
287			t2 = (BN_ULLONG)d1*q;
288
289			for (;;) {
290			if (t2 <= ((((BN_ULLONG)rem) << BN_BITS2) \|
291			wnump[-2]))
292			break;
293			q--;
294			rem += d0;
295			if (rem < d0) break; /* don't let rem overflow */
296			t2 -= d1;
297			}
298			#else /* !BN_LLONG */
299			BN_ULONG t2l, t2h;
300
301		14231551	q = bn_div_words(n0, n1, d0);
302			#ifndef REMAINDER_IS_ALREADY_CALCULATED
303			rem = (n1 - q*d0)&BN_MASK2;
304			#endif
305
306			#if defined(BN_UMULT_LOHI)
307		14231551	BN_UMULT_LOHI(t2l, t2h, d1, q);
308			#elif defined(BN_UMULT_HIGH)
309			t2l = d1 * q;
310			t2h = BN_UMULT_HIGH(d1, q);
311			#else
312			{
313			BN_ULONG ql, qh;
314			t2l = LBITS(d1);
315			t2h = HBITS(d1);
316			ql = LBITS(q);
317			qh = HBITS(q);
318			mul64(t2l, t2h, ql, qh); /* t2=(BN_ULLONG)d1q; /
319			}
320			#endif
321
322		15302245	for (;;) {
323	✓✓✓✓	15419179	if ((t2h < rem) \|\|
324	✓✓	1904332	((t2h == rem) && (t2l <= wnump[-2])))
325			break;
326		1670965	q--;
327		1670965	rem += d0;
328	✓✓	1670965	if (rem < d0)
329			break; /* don't let rem overflow */
330	✓✓	1070694	if (t2l < d1)
331		509664	t2h--;
332		1070694	t2l -= d1;
333			}
334			#endif /* !BN_LLONG */
335			}
336			#endif /* !BN_DIV3W */
337
338		14232309	l0 = bn_mul_words(tmp->d, sdiv->d, div_n, q);
339		14232309	tmp->d[div_n] = l0;
340		14232309	wnum.d--;
341			/* ingore top values of the bignums just sub the two
342			* BN_ULONG arrays with bn_sub_words */
343	✓✓	14232309	if (bn_sub_words(wnum.d, wnum.d, tmp->d, div_n + 1)) {
344			/* Note: As we have considered only the leading
345			* two BN_ULONGs in the calculation of q, sdiv * q
346			* might be greater than wnum (but then (q-1) * sdiv
347			* is less or equal than wnum)
348			*/
349		3158	q--;
350	✓✗	3158	if (bn_add_words(wnum.d, wnum.d, sdiv->d, div_n))
351			/* we can't have an overflow here (assuming
352			* that q != 0, but if q == 0 then tmp is
353			* zero anyway) */
354		3158	(*wnump)++;
355			}
356			/* store part of the result */
357		14232309	*resp = q;
358			}
359	✓✗✓✓ ✓✓	67146649	bn_correct_top(snum);
360	✓✓	4338445	if (rm != NULL) {
361			/* Keep a copy of the neg flag in num because if rm==num
362			* BN_rshift() will overwrite it.
363			*/
364		4242146	int neg = num->neg;
365		4242146	BN_rshift(rm, snum, norm_shift);
366	✓✓	4242146	if (!BN_is_zero(rm))
367		4173482	rm->neg = neg;
368			bn_check_top(rm);
369		4242146	}
370	✓✓	4338445	if (no_branch)
371	✓✗✓✓ ✓✓	35971119	bn_correct_top(res);
372		4338445	BN_CTX_end(ctx);
373		4338445	return (1);
374
375			err:
376			bn_check_top(rm);
377			BN_CTX_end(ctx);
378			return (0);
379		4343896	}
380
381			int
382			BN_div(BIGNUM dv, BIGNUM rm, const BIGNUM num, const BIGNUM divisor,
383			BN_CTX *ctx)
384			{
385	✓✗	299620	int ct = ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0) \|\|
386		74905	(BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0));
387
388		74905	return BN_div_internal(dv, rm, num, divisor, ctx, ct);
389			}
390
391			int
392			BN_div_nonct(BIGNUM dv, BIGNUM rm, const BIGNUM num, const BIGNUM divisor,
393			BN_CTX *ctx)
394			{
395			return BN_div_internal(dv, rm, num, divisor, ctx, 0);
396			}
397
398			int
399			BN_div_ct(BIGNUM dv, BIGNUM rm, const BIGNUM num, const BIGNUM divisor,
400			BN_CTX *ctx)
401			{
402		8537982	return BN_div_internal(dv, rm, num, divisor, ctx, 1);
403			}