[thirdparty/openssl.git] / crypto / bn / bn_div.c

/* 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);
	bn_wexpand(dv,1);
	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 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.
 */
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;
	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);
	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) goto err;
	tmp->neg=0;

	/* 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 */
	BN_init(&wnum);
	wnum.flags = BN_FLG_STATIC_DATA; /* prevent accidental "expands" */
	wnum.d=	 &(snum->d[loop]);
	wnum.top= div_n;
	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;

	bn_correct_top(&wnum);
	if (BN_ucmp(&wnum,sdiv) >= 0)
		{
		if (!BN_usub(&wnum,&wnum,sdiv)) goto err;
		*resp=1;
		res->d[res->top-1]=1;
		}
	else
		res->top--;
	if (res->top == 0)
		res->neg = 0;
	resp--;

	for (i=0; i<loop-1; i++)
		{
		BN_ULONG q,l0;
#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,ql,qh;

			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
			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);
		wnum.d--; wnum.top++; wnum.dmax++;
		tmp->d[div_n]=l0;
		/* XXX: Couldn't we replace this with;
		 *    tmp->top = div_n;
		 *    bn_fix_top(tmp);
		 */
		for (j=div_n+1; j>0; j--)
			if (tmp->d[j-1]) break;
		tmp->top=j;

		j=wnum.top;
		bn_correct_top(&wnum);
		if (!BN_sub(&wnum,&wnum,tmp)) goto err;

		snum->top=snum->top+wnum.top-j;

		if (wnum.neg)
			{
			q--;
			j=wnum.top;
			if (!BN_add(&wnum,&wnum,sdiv)) goto err;
			snum->top+=wnum.top-j;
			}
		*(resp--)=q;
		wnump--;
		}
	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_correct_top(snum);
		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);
	}

#endif
Commit	Line	Data
d02b48c6	1	/* crypto/bn/bn_div.c */
58964a49	2	/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
d02b48c6 RE	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>
84c15db5	60	#include <openssl/bn.h>
d02b48c6 RE	61	#include "cryptlib.h"
	62	#include "bn_lcl.h"
	63
78a0c1f1	64
d02b48c6	65	/* The old slow way */
4a6222d7	66	#if 0
0bde1089 UM	67	int BN_div(BIGNUM dv, BIGNUM rem, const BIGNUM m, const BIGNUM d,
0bde1089 UM	68	BN_CTX *ctx)
d02b48c6 RE	69	{
d02b48c6 RE	70	int i,nm,nd;
9b141126	71	int ret = 0;
d02b48c6 RE	72	BIGNUM *D;
d02b48c6 RE	73
dfeab068 RE	74	bn_check_top(m);
dfeab068 RE	75	bn_check_top(d);
d02b48c6 RE	76	if (BN_is_zero(d))
	77	{
	78	BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO);
	79	return(0);
	80	}
	81
	82	if (BN_ucmp(m,d) < 0)
	83	{
	84	if (rem != NULL)
	85	{ if (BN_copy(rem,m) == NULL) return(0); }
	86	if (dv != NULL) BN_zero(dv);
	87	return(1);
	88	}
	89
9b141126 UM	90	BN_CTX_start(ctx);
	91	D = BN_CTX_get(ctx);
	92	if (dv == NULL) dv = BN_CTX_get(ctx);
	93	if (rem == NULL) rem = BN_CTX_get(ctx);
	94	if (D == NULL \|\| dv == NULL \|\| rem == NULL)
	95	goto end;
d02b48c6 RE	96
	97	nd=BN_num_bits(d);
	98	nm=BN_num_bits(m);
9b141126 UM	99	if (BN_copy(D,d) == NULL) goto end;
9b141126 UM	100	if (BN_copy(rem,m) == NULL) goto end;
d02b48c6 RE	101
	102	/* The next 2 are needed so we can do a dv->d[0]\|=1 later
	103	* since BN_lshift1 will only work once there is a value :-) */
	104	BN_zero(dv);
dfeab068	105	bn_wexpand(dv,1);
d02b48c6 RE	106	dv->top=1;
d02b48c6 RE	107
9b141126	108	if (!BN_lshift(D,D,nm-nd)) goto end;
d02b48c6 RE	109	for (i=nm-nd; i>=0; i--)
d02b48c6 RE	110	{
9b141126	111	if (!BN_lshift1(dv,dv)) goto end;
d02b48c6 RE	112	if (BN_ucmp(rem,D) >= 0)
	113	{
	114	dv->d[0]\|=1;
9b141126	115	if (!BN_usub(rem,rem,D)) goto end;
d02b48c6 RE	116	}
d02b48c6 RE	117	/* CAN IMPROVE (and have now :=) */
9b141126	118	if (!BN_rshift1(D,D)) goto end;
d02b48c6 RE	119	}
	120	rem->neg=BN_is_zero(rem)?0:m->neg;
	121	dv->neg=m->neg^d->neg;
9b141126 UM	122	ret = 1;
	123	end:
	124	BN_CTX_end(ctx);
	125	return(ret);
d02b48c6 RE	126	}
	127
	128	#else
	129
cf1b7d96 RL	130	#if !defined(OPENSSL_NO_ASM) && !defined(OPENSSL_NO_INLINE_ASM) \
cf1b7d96 RL	131	&& !defined(PEDANTIC) && !defined(BN_DIV3W)
4a6222d7	132	# if defined(__GNUC__) && __GNUC__>=2
5dd955dc	133	# if defined(__i386) \|\| defined (__i386__)
4a6222d7 UM	134	/*
	135	* There were two reasons for implementing this template:
	136	* - GNU C generates a call to a function (__udivdi3 to be exact)
	137	* in reply to ((((BN_ULLONG)n0)<<BN_BITS2)\|n1)/d0 (I fail to
	138	* understand why...);
	139	* - divl doesn't only calculate quotient, but also leaves
	140	* remainder in %edx which we can definitely use here:-)
	141	*
	142	* <appro@fy.chalmers.se>
	143	*/
	144	# define bn_div_words(n0,n1,d0) \
	145	({ asm volatile ( \
	146	"divl %4" \
	147	: "=a"(q), "=d"(rem) \
	148	: "a"(n1), "d"(n0), "g"(d0) \
	149	: "cc"); \
	150	q; \
	151	})
	152	# define REMAINDER_IS_ALREADY_CALCULATED
2f98abbc AP	153	# elif defined(__x86_64) && defined(SIXTY_FOUR_BIT_LONG)
	154	/*
	155	* Same story here, but it's 128-bit by 64-bit division. Wow!
	156	* <appro@fy.chalmers.se>
	157	*/
	158	# define bn_div_words(n0,n1,d0) \
	159	({ asm volatile ( \
	160	"divq %4" \
	161	: "=a"(q), "=d"(rem) \
	162	: "a"(n1), "d"(n0), "g"(d0) \
	163	: "cc"); \
	164	q; \
	165	})
	166	# define REMAINDER_IS_ALREADY_CALCULATED
4a6222d7 UM	167	# endif /* __<cpu> */
4a6222d7 UM	168	# endif /* __GNUC__ */
cf1b7d96	169	#endif /* OPENSSL_NO_ASM */
4a6222d7	170
78a0c1f1 BM	171
	172	/* BN_div computes dv := num / divisor, rounding towards zero, and sets up
	173	* rm such that dv*divisor + rm = num holds.
	174	* Thus:
	175	* dv->neg == num->neg ^ divisor->neg (unless the result is zero)
	176	* rm->neg == num->neg (unless the remainder is zero)
	177	* If 'dv' or 'rm' is NULL, the respective value is not returned.
	178	*/
84c15db5 BL	179	int BN_div(BIGNUM dv, BIGNUM rm, const BIGNUM num, const BIGNUM divisor,
84c15db5 BL	180	BN_CTX *ctx)
d02b48c6 RE	181	{
	182	int norm_shift,i,j,loop;
	183	BIGNUM tmp,wnum,snum,sdiv,res;
	184	BN_ULONG resp,wnump;
	185	BN_ULONG d0,d1;
	186	int num_n,div_n;
	187
5c0c2280 GT	188	bn_check_top(dv);
5c0c2280 GT	189	bn_check_top(rm);
dfeab068 RE	190	bn_check_top(num);
	191	bn_check_top(divisor);
	192
58964a49	193	if (BN_is_zero(divisor))
d02b48c6 RE	194	{
	195	BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO);
	196	return(0);
	197	}
	198
	199	if (BN_ucmp(num,divisor) < 0)
	200	{
	201	if (rm != NULL)
	202	{ if (BN_copy(rm,num) == NULL) return(0); }
	203	if (dv != NULL) BN_zero(dv);
	204	return(1);
	205	}
	206
9b141126 UM	207	BN_CTX_start(ctx);
9b141126 UM	208	tmp=BN_CTX_get(ctx);
9b141126 UM	209	snum=BN_CTX_get(ctx);
9b141126 UM	210	sdiv=BN_CTX_get(ctx);
d02b48c6	211	if (dv == NULL)
9b141126	212	res=BN_CTX_get(ctx);
d02b48c6	213	else res=dv;
7f7b8d68 BM	214	if (sdiv == NULL \|\| res == NULL) goto err;
7f7b8d68 BM	215	tmp->neg=0;
d02b48c6 RE	216
	217	/* First we normalise the numbers */
	218	norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
9cdf87f1	219	if (!(BN_lshift(sdiv,divisor,norm_shift))) goto err;
d02b48c6 RE	220	sdiv->neg=0;
d02b48c6 RE	221	norm_shift+=BN_BITS2;
9cdf87f1	222	if (!(BN_lshift(snum,num,norm_shift))) goto err;
d02b48c6 RE	223	snum->neg=0;
	224	div_n=sdiv->top;
	225	num_n=snum->top;
	226	loop=num_n-div_n;
	227
	228	/* Lets setup a 'window' into snum
	229	* This is the part that corresponds to the current
	230	* 'area' being divided */
dfeab068	231	BN_init(&wnum);
a9fd78f9	232	wnum.flags = BN_FLG_STATIC_DATA; /* prevent accidental "expands" */
d02b48c6 RE	233	wnum.d= &(snum->d[loop]);
d02b48c6 RE	234	wnum.top= div_n;
a9fd78f9	235	wnum.dmax= snum->dmax - loop; /* so we don't step out of bounds */
d02b48c6 RE	236
d02b48c6 RE	237	/* Get the top 2 words of sdiv */
5c0c2280	238	/* div_n=sdiv->top; */
d02b48c6 RE	239	d0=sdiv->d[div_n-1];
	240	d1=(div_n == 1)?0:sdiv->d[div_n-2];
	241
	242	/* pointer to the 'top' of snum */
	243	wnump= &(snum->d[num_n-1]);
	244
	245	/* Setup to 'res' */
	246	res->neg= (num->neg^divisor->neg);
58964a49	247	if (!bn_wexpand(res,(loop+1))) goto err;
dfeab068	248	res->top=loop;
d02b48c6 RE	249	resp= &(res->d[loop-1]);
	250
	251	/* space for temp */
58964a49	252	if (!bn_wexpand(tmp,(div_n+1))) goto err;
d02b48c6	253
d870740c	254	bn_correct_top(&wnum);
d02b48c6 RE	255	if (BN_ucmp(&wnum,sdiv) >= 0)
d02b48c6 RE	256	{
dfeab068	257	if (!BN_usub(&wnum,&wnum,sdiv)) goto err;
d02b48c6 RE	258	*resp=1;
	259	res->d[res->top-1]=1;
	260	}
	261	else
	262	res->top--;
80d89e6a BM	263	if (res->top == 0)
80d89e6a BM	264	res->neg = 0;
d02b48c6 RE	265	resp--;
	266
	267	for (i=0; i<loop-1; i++)
	268	{
0dd25e36	269	BN_ULONG q,l0;
cf1b7d96	270	#if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM)
500230ee	271	BN_ULONG bn_div_3_words(BN_ULONG*,BN_ULONG,BN_ULONG);
0bbd0352	272	q=bn_div_3_words(wnump,d1,d0);
0dd25e36	273	#else
4c22909e	274	BN_ULONG n0,n1,rem=0;
d02b48c6	275
d02b48c6 RE	276	n0=wnump[0];
	277	n1=wnump[-1];
	278	if (n0 == d0)
	279	q=BN_MASK2;
4a6222d7 UM	280	else /* n0 < d0 */
	281	{
	282	#ifdef BN_LLONG
	283	BN_ULLONG t2;
	284
4c22909e	285	#if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)
8e1589ec	286	q=(BN_ULONG)(((((BN_ULLONG)n0)<<BN_BITS2)\|n1)/d0);
0dd25e36	287	#else
dfeab068	288	q=bn_div_words(n0,n1,d0);
3c801fa4 RL	289	#ifdef BN_DEBUG_LEVITTE
	290	fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
	291	X) -> 0x%08X\n",
	292	n0, n1, d0, q);
	293	#endif
0dd25e36	294	#endif
0dd25e36	295
fe7cd164	296	#ifndef REMAINDER_IS_ALREADY_CALCULATED
4a6222d7 UM	297	/*
	298	* rem doesn't have to be BN_ULLONG. The least we
	299	* know it's less that d0, isn't it?
	300	*/
	301	rem=(n1-q*d0)&BN_MASK2;
4c22909e	302	#endif
4a6222d7 UM	303	t2=(BN_ULLONG)d1*q;
	304
	305	for (;;)
	306	{
	307	if (t2 <= ((((BN_ULLONG)rem)<<BN_BITS2)\|wnump[-2]))
	308	break;
	309	q--;
	310	rem += d0;
	311	if (rem < d0) break; /* don't let rem overflow */
	312	t2 -= d1;
	313	}
	314	#else /* !BN_LLONG */
	315	BN_ULONG t2l,t2h,ql,qh;
0dd25e36	316
4a6222d7	317	q=bn_div_words(n0,n1,d0);
3c801fa4 RL	318	#ifdef BN_DEBUG_LEVITTE
	319	fprintf(stderr,"DEBUG: bn_div_words(0x%08X,0x%08X,0x%08\
	320	X) -> 0x%08X\n",
	321	n0, n1, d0, q);
	322	#endif
fe7cd164	323	#ifndef REMAINDER_IS_ALREADY_CALCULATED
4a6222d7	324	rem=(n1-q*d0)&BN_MASK2;
4c22909e	325	#endif
4a6222d7	326
2f98abbc AP	327	#if defined(BN_UMULT_LOHI)
	328	BN_UMULT_LOHI(t2l,t2h,d1,q);
	329	#elif defined(BN_UMULT_HIGH)
4a6222d7 UM	330	t2l = d1 * q;
4a6222d7 UM	331	t2h = BN_UMULT_HIGH(d1,q);
fb81ac5e	332	#else
4a6222d7 UM	333	t2l=LBITS(d1); t2h=HBITS(d1);
	334	ql =LBITS(q); qh =HBITS(q);
	335	mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1q; /
fb81ac5e	336	#endif
0dd25e36	337
4a6222d7 UM	338	for (;;)
	339	{
	340	if ((t2h < rem) \|\|
	341	((t2h == rem) && (t2l <= wnump[-2])))
	342	break;
	343	q--;
	344	rem += d0;
	345	if (rem < d0) break; /* don't let rem overflow */
	346	if (t2l < d1) t2h--; t2l -= d1;
	347	}
	348	#endif /* !BN_LLONG */
d02b48c6	349	}
4c22909e	350	#endif /* !BN_DIV3W */
4a6222d7	351
58964a49	352	l0=bn_mul_words(tmp->d,sdiv->d,div_n,q);
a9fd78f9	353	wnum.d--; wnum.top++; wnum.dmax++;
d02b48c6	354	tmp->d[div_n]=l0;
c4db1a8b GT	355	/* XXX: Couldn't we replace this with;
	356	* tmp->top = div_n;
	357	* bn_fix_top(tmp);
	358	*/
d02b48c6 RE	359	for (j=div_n+1; j>0; j--)
	360	if (tmp->d[j-1]) break;
	361	tmp->top=j;
	362
	363	j=wnum.top;
d870740c	364	bn_correct_top(&wnum);
9cdf87f1	365	if (!BN_sub(&wnum,&wnum,tmp)) goto err;
d02b48c6 RE	366
	367	snum->top=snum->top+wnum.top-j;
	368
	369	if (wnum.neg)
	370	{
	371	q--;
	372	j=wnum.top;
9cdf87f1	373	if (!BN_add(&wnum,&wnum,sdiv)) goto err;
d02b48c6 RE	374	snum->top+=wnum.top-j;
	375	}
	376	*(resp--)=q;
	377	wnump--;
	378	}
	379	if (rm != NULL)
	380	{
3d2e469c DSH	381	/* Keep a copy of the neg flag in num because if rm==num
	382	* BN_rshift() will overwrite it.
	383	*/
	384	int neg = num->neg;
d870740c	385	bn_correct_top(snum);
d02b48c6	386	BN_rshift(rm,snum,norm_shift);
78a0c1f1	387	if (!BN_is_zero(rm))
3d2e469c	388	rm->neg = neg;
d870740c	389	bn_check_top(rm);
d02b48c6	390	}
9b141126	391	BN_CTX_end(ctx);
d02b48c6 RE	392	return(1);
d02b48c6 RE	393	err:
d870740c	394	bn_check_top(rm);
4a6222d7	395	BN_CTX_end(ctx);
d02b48c6 RE	396	return(0);
	397	}
	398
	399	#endif