[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, 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);
		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);
		}

	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);
	if (BN_copy(D,d) == NULL) return(0);
	if (BN_copy(rem,m) == NULL) return(0);

	/* 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);
	for (i=nm-nd; i>=0; i--)
		{
		if (!BN_lshift1(dv,dv)) return(0);
		if (BN_ucmp(rem,D) >= 0)
			{
			dv->d[0]|=1;
			if (!BN_usub(rem,rem,D)) return(0);
			}
/* CAN IMPROVE (and have now :=) */
		if (!BN_rshift1(D,D)) return(0);
		}
	rem->neg=BN_is_zero(rem)?0:m->neg;
	dv->neg=m->neg^d->neg;
	return(1);
	}

#else

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(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);
		}

	tmp= &(ctx->bn[ctx->tos]);
	tmp->neg=0;
	snum= &(ctx->bn[ctx->tos+1]);
	sdiv= &(ctx->bn[ctx->tos+2]);
	if (dv == NULL)
		res= &(ctx->bn[ctx->tos+3]);
	else	res=dv;

	/* First we normalise the numbers */
	norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
	BN_lshift(sdiv,divisor,norm_shift);
	sdiv->neg=0;
	norm_shift+=BN_BITS2;
	BN_lshift(snum,num,norm_shift);
	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.d=	 &(snum->d[loop]);
	wnum.top= div_n;
	wnum.max= snum->max+1; /* a bit of a lie */

	/* Get the top 2 words of sdiv */
	/* i=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_usub(&wnum,&wnum,sdiv)) goto err;
		*resp=1;
		res->d[res->top-1]=1;
		}
	else
		res->top--;
	resp--;

	for (i=0; i<loop-1; i++)
		{
		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;

		n0=wnump[0];
		n1=wnump[-1];
		if (n0 == d0)
			q=BN_MASK2;
		else
#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 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 (;;)
			{
                        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 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 (;;)
			{
			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--)
			if (tmp->d[j-1]) break;
		tmp->top=j;

		j=wnum.top;
		BN_sub(&wnum,&wnum,tmp);

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

		if (wnum.neg)
			{
			q--;
			j=wnum.top;
			BN_add(&wnum,&wnum,sdiv);
			snum->top+=wnum.top-j;
			}
		*(resp--)=q;
		wnump--;
		}
	if (rm != NULL)
		{
		BN_rshift(rm,snum,norm_shift);
		rm->neg=num->neg;
		}
	return(1);
err:
	return(0);
	}

#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
	}
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
	64	/* The old slow way */
	65	#if 0
6b691a5c	66	int BN_div(BIGNUM dv, BIGNUM rem, BIGNUM m, BIGNUM d, BN_CTX *ctx)
d02b48c6 RE	67	{
	68	int i,nm,nd;
	69	BIGNUM *D;
	70
dfeab068 RE	71	bn_check_top(m);
dfeab068 RE	72	bn_check_top(d);
d02b48c6 RE	73	if (BN_is_zero(d))
	74	{
	75	BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO);
	76	return(0);
	77	}
	78
	79	if (BN_ucmp(m,d) < 0)
	80	{
	81	if (rem != NULL)
	82	{ if (BN_copy(rem,m) == NULL) return(0); }
	83	if (dv != NULL) BN_zero(dv);
	84	return(1);
	85	}
	86
dfeab068 RE	87	D= &(ctx->bn[ctx->tos]);
	88	if (dv == NULL) dv= &(ctx->bn[ctx->tos+1]);
	89	if (rem == NULL) rem= &(ctx->bn[ctx->tos+2]);
d02b48c6 RE	90
	91	nd=BN_num_bits(d);
	92	nm=BN_num_bits(m);
	93	if (BN_copy(D,d) == NULL) return(0);
	94	if (BN_copy(rem,m) == NULL) return(0);
	95
	96	/* The next 2 are needed so we can do a dv->d[0]\|=1 later
	97	* since BN_lshift1 will only work once there is a value :-) */
	98	BN_zero(dv);
dfeab068	99	bn_wexpand(dv,1);
d02b48c6 RE	100	dv->top=1;
	101
	102	if (!BN_lshift(D,D,nm-nd)) return(0);
	103	for (i=nm-nd; i>=0; i--)
	104	{
	105	if (!BN_lshift1(dv,dv)) return(0);
	106	if (BN_ucmp(rem,D) >= 0)
	107	{
	108	dv->d[0]\|=1;
dfeab068	109	if (!BN_usub(rem,rem,D)) return(0);
d02b48c6 RE	110	}
	111	/* CAN IMPROVE (and have now :=) */
	112	if (!BN_rshift1(D,D)) return(0);
	113	}
	114	rem->neg=BN_is_zero(rem)?0:m->neg;
	115	dv->neg=m->neg^d->neg;
	116	return(1);
	117	}
	118
	119	#else
	120
84c15db5 BL	121	int BN_div(BIGNUM dv, BIGNUM rm, const BIGNUM num, const BIGNUM divisor,
84c15db5 BL	122	BN_CTX *ctx)
d02b48c6 RE	123	{
	124	int norm_shift,i,j,loop;
	125	BIGNUM tmp,wnum,snum,sdiv,res;
	126	BN_ULONG resp,wnump;
	127	BN_ULONG d0,d1;
	128	int num_n,div_n;
	129
dfeab068 RE	130	bn_check_top(num);
	131	bn_check_top(divisor);
	132
58964a49	133	if (BN_is_zero(divisor))
d02b48c6 RE	134	{
	135	BNerr(BN_F_BN_DIV,BN_R_DIV_BY_ZERO);
	136	return(0);
	137	}
	138
	139	if (BN_ucmp(num,divisor) < 0)
	140	{
	141	if (rm != NULL)
	142	{ if (BN_copy(rm,num) == NULL) return(0); }
	143	if (dv != NULL) BN_zero(dv);
	144	return(1);
	145	}
	146
dfeab068	147	tmp= &(ctx->bn[ctx->tos]);
d02b48c6	148	tmp->neg=0;
dfeab068 RE	149	snum= &(ctx->bn[ctx->tos+1]);
dfeab068 RE	150	sdiv= &(ctx->bn[ctx->tos+2]);
d02b48c6	151	if (dv == NULL)
dfeab068	152	res= &(ctx->bn[ctx->tos+3]);
d02b48c6 RE	153	else res=dv;
	154
	155	/* First we normalise the numbers */
	156	norm_shift=BN_BITS2-((BN_num_bits(divisor))%BN_BITS2);
	157	BN_lshift(sdiv,divisor,norm_shift);
	158	sdiv->neg=0;
	159	norm_shift+=BN_BITS2;
	160	BN_lshift(snum,num,norm_shift);
	161	snum->neg=0;
	162	div_n=sdiv->top;
	163	num_n=snum->top;
	164	loop=num_n-div_n;
	165
	166	/* Lets setup a 'window' into snum
	167	* This is the part that corresponds to the current
	168	* 'area' being divided */
dfeab068	169	BN_init(&wnum);
d02b48c6 RE	170	wnum.d= &(snum->d[loop]);
d02b48c6 RE	171	wnum.top= div_n;
dfeab068	172	wnum.max= snum->max+1; /* a bit of a lie */
d02b48c6 RE	173
	174	/* Get the top 2 words of sdiv */
	175	/* i=sdiv->top; */
	176	d0=sdiv->d[div_n-1];
	177	d1=(div_n == 1)?0:sdiv->d[div_n-2];
	178
	179	/* pointer to the 'top' of snum */
	180	wnump= &(snum->d[num_n-1]);
	181
	182	/* Setup to 'res' */
	183	res->neg= (num->neg^divisor->neg);
58964a49	184	if (!bn_wexpand(res,(loop+1))) goto err;
dfeab068	185	res->top=loop;
d02b48c6 RE	186	resp= &(res->d[loop-1]);
	187
	188	/* space for temp */
58964a49	189	if (!bn_wexpand(tmp,(div_n+1))) goto err;
d02b48c6 RE	190
	191	if (BN_ucmp(&wnum,sdiv) >= 0)
	192	{
dfeab068	193	if (!BN_usub(&wnum,&wnum,sdiv)) goto err;
d02b48c6 RE	194	*resp=1;
	195	res->d[res->top-1]=1;
	196	}
	197	else
	198	res->top--;
	199	resp--;
	200
	201	for (i=0; i<loop-1; i++)
	202	{
0dd25e36 AP	203	BN_ULONG q,l0;
	204	#ifdef BN_DIV3W
	205	q=bn_div_3_words(wnump,d0,d1);
	206	#else
4c22909e	207
97e84e38	208	#if !defined(NO_ASM) && !defined(PEDANTIC)
4c22909e AP	209	# if defined(__GNUC__) && __GNUC__>=2
	210	# if defined(__i386)
	211	/*
	212	* There were two reasons for implementing this template:
	213	* - GNU C generates a call to a function (__udivdi3 to be exact)
	214	* in reply to ((((BN_ULLONG)n0)<<BN_BITS2)\|n1)/d0 (I fail to
	215	* understand why...);
	216	* - divl doesn't only calculate quotient, but also leaves
	217	* remainder in %edx which we can definitely use here:-)
	218	*
	219	* <appro@fy.chalmers.se>
	220	*/
	221	# define bn_div_words(n0,n1,d0) \
	222	({ asm volatile ( \
	223	"divl %4" \
	224	: "=a"(q), "=d"(rem) \
	225	: "a"(n1), "d"(n0), "g"(d0) \
	226	: "cc"); \
	227	q; \
	228	})
	229	# define REMINDER_IS_ALREADY_CALCULATED
	230	# endif /* __<cpu> */
	231	# endif /* __GNUC__ */
	232	#endif /* NO_ASM */
	233	BN_ULONG n0,n1,rem=0;
d02b48c6	234
d02b48c6 RE	235	n0=wnump[0];
	236	n1=wnump[-1];
	237	if (n0 == d0)
	238	q=BN_MASK2;
	239	else
4c22909e AP	240	#if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)
4c22909e AP	241	q=((((BN_ULLONG)n0)<<BN_BITS2)\|n1)/d0;
0dd25e36	242	#else
dfeab068	243	q=bn_div_words(n0,n1,d0);
0dd25e36	244	#endif
d02b48c6 RE	245	{
d02b48c6 RE	246	#ifdef BN_LLONG
0dd25e36 AP	247	BN_ULLONG t2;
0dd25e36 AP	248
4c22909e	249	#ifndef REMINDER_IS_ALREADY_CALCULATED
0dd25e36 AP	250	/*
	251	* rem doesn't have to be BN_ULLONG. The least we
	252	* know it's less that d0, isn't it?
	253	*/
	254	rem=(n1-q*d0)&BN_MASK2;
4c22909e	255	#endif
0dd25e36	256	t2=(BN_ULLONG)d1*q;
4c22909e	257
d02b48c6 RE	258	for (;;)
d02b48c6 RE	259	{
0dd25e36	260	if (t2 <= ((((BN_ULLONG)rem)<<BN_BITS2)\|wnump[-2]))
d02b48c6 RE	261	break;
d02b48c6 RE	262	q--;
0dd25e36 AP	263	rem += d0;
	264	if (rem < d0) break; /* don't let rem overflow */
	265	t2 -= d1;
d02b48c6 RE	266	}
d02b48c6 RE	267	#else
0dd25e36 AP	268	BN_ULONG t2l,t2h,ql,qh;
0dd25e36 AP	269
4c22909e	270	#ifndef REMINDER_IS_ALREADY_CALCULATED
0dd25e36 AP	271	/*
	272	* It's more than enough with the only multiplication.
	273	* See the comment above in BN_LLONG section...
	274	*/
	275	rem=(n1-q*d0)&BN_MASK2;
4c22909e	276	#endif
0dd25e36 AP	277	t2l=LBITS(d1); t2h=HBITS(d1);
	278	ql =LBITS(q); qh =HBITS(q);
	279	mul64(t2l,t2h,ql,qh); /* t2=(BN_ULLONG)d1q; /
	280
d02b48c6 RE	281	for (;;)
d02b48c6 RE	282	{
0dd25e36 AP	283	if ((t2h < rem) \|\|
	284	((t2h == rem) && (t2l <= wnump[-2])))
	285	break;
d02b48c6	286	q--;
0dd25e36 AP	287	rem += d0;
	288	if (rem < d0) break; /* don't let rem overflow */
	289	if (t2l < d1) t2h--; t2l -= d1;
d02b48c6 RE	290	}
	291	#endif
	292	}
4c22909e	293	#endif /* !BN_DIV3W */
0dd25e36	294	wnum.d--; wnum.top++;
58964a49	295	l0=bn_mul_words(tmp->d,sdiv->d,div_n,q);
d02b48c6 RE	296	tmp->d[div_n]=l0;
	297	for (j=div_n+1; j>0; j--)
	298	if (tmp->d[j-1]) break;
	299	tmp->top=j;
	300
	301	j=wnum.top;
	302	BN_sub(&wnum,&wnum,tmp);
	303
	304	snum->top=snum->top+wnum.top-j;
	305
	306	if (wnum.neg)
	307	{
	308	q--;
	309	j=wnum.top;
	310	BN_add(&wnum,&wnum,sdiv);
	311	snum->top+=wnum.top-j;
	312	}
	313	*(resp--)=q;
	314	wnump--;
	315	}
	316	if (rm != NULL)
	317	{
	318	BN_rshift(rm,snum,norm_shift);
	319	rm->neg=num->neg;
	320	}
	321	return(1);
	322	err:
	323	return(0);
	324	}
	325
	326	#endif
dfeab068 RE	327
dfeab068 RE	328	/* rem != m */
84c15db5	329	int BN_mod(BIGNUM rem, const BIGNUM m, const BIGNUM d, BN_CTX ctx)
dfeab068 RE	330	{
	331	#if 0 /* The old slow way */
	332	int i,nm,nd;
	333	BIGNUM *dv;
	334
	335	if (BN_ucmp(m,d) < 0)
	336	return((BN_copy(rem,m) == NULL)?0:1);
	337
	338	dv= &(ctx->bn[ctx->tos]);
	339
	340	if (!BN_copy(rem,m)) return(0);
	341
	342	nm=BN_num_bits(rem);
	343	nd=BN_num_bits(d);
	344	if (!BN_lshift(dv,d,nm-nd)) return(0);
	345	for (i=nm-nd; i>=0; i--)
	346	{
	347	if (BN_cmp(rem,dv) >= 0)
	348	{
	349	if (!BN_sub(rem,rem,dv)) return(0);
	350	}
	351	if (!BN_rshift1(dv,dv)) return(0);
	352	}
	353	return(1);
	354	#else
	355	return(BN_div(NULL,rem,m,d,ctx));
	356	#endif
	357	}
	358