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

/* crypto/bn/bn_add.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 "cryptlib.h"
#include "bn_lcl.h"

/* r can == a or b */
int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
	{
	const BIGNUM *tmp;
	int a_neg = a->neg, ret;

	bn_check_top(a);
	bn_check_top(b);

	/*  a +  b	a+b
	 *  a + -b	a-b
	 * -a +  b	b-a
	 * -a + -b	-(a+b)
	 */
	if (a_neg ^ b->neg)
		{
		/* only one is negative */
		if (a_neg)
			{ tmp=a; a=b; b=tmp; }

		/* we are now a - b */

		if (BN_ucmp(a,b) < 0)
			{
			if (!BN_usub(r,b,a)) return(0);
			r->neg=1;
			}
		else
			{
			if (!BN_usub(r,a,b)) return(0);
			r->neg=0;
			}
		return(1);
		}

	ret = BN_uadd(r,a,b);
	r->neg = a_neg;
	bn_check_top(r);
	return ret;
	}

/* unsigned add of b to a */
int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
	{
	int max,min,dif;
	BN_ULONG *ap,*bp,*rp,carry,t1,t2;
	const BIGNUM *tmp;

	bn_check_top(a);
	bn_check_top(b);

	if (a->top < b->top)
		{ tmp=a; a=b; b=tmp; }
	max = a->top;
	min = b->top;
	dif = max - min;

	if (bn_wexpand(r,max+1) == NULL)
		return 0;

	r->top=max;


	ap=a->d;
	bp=b->d;
	rp=r->d;

	carry=bn_add_words(rp,ap,bp,min);
	rp+=min;
	ap+=min;
	bp+=min;

	if (carry)
		{
		while (dif)
			{
			dif--;
			t1 = *(ap++);
			t2 = (t1+1) & BN_MASK2;
			*(rp++) = t2;
			if (t2)
				{
				carry=0;
				break;
				}
			}
		if (carry)
			{
			/* carry != 0 => dif == 0 */
			*rp = 1;
			r->top++;
			}
		}
	if (dif && rp != ap)
		while (dif--)
			/* copy remaining words if ap != rp */
			*(rp++) = *(ap++);
	r->neg = 0;
	bn_check_top(r);
	return 1;
	}

/* unsigned subtraction of b from a, a must be larger than b. */
int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
	{
	int max,min,dif;
	register BN_ULONG t1,t2,*ap,*bp,*rp;
	int i,carry;
#if defined(IRIX_CC_BUG) && !defined(LINT)
	int dummy;
#endif

	bn_check_top(a);
	bn_check_top(b);

	max = a->top;
	min = b->top;
	dif = max - min;

	if (dif < 0)	/* hmm... should not be happening */
		{
		BNerr(BN_F_BN_USUB,BN_R_ARG2_LT_ARG3);
		return(0);
		}

	if (bn_wexpand(r,max) == NULL) return(0);

	ap=a->d;
	bp=b->d;
	rp=r->d;

#if 1
	carry=0;
	for (i = min; i != 0; i--)
		{
		t1= *(ap++);
		t2= *(bp++);
		if (carry)
			{
			carry=(t1 <= t2);
			t1=(t1-t2-1)&BN_MASK2;
			}
		else
			{
			carry=(t1 < t2);
			t1=(t1-t2)&BN_MASK2;
			}
#if defined(IRIX_CC_BUG) && !defined(LINT)
		dummy=t1;
#endif
		*(rp++)=t1&BN_MASK2;
		}
#else
	carry=bn_sub_words(rp,ap,bp,min);
	ap+=min;
	bp+=min;
	rp+=min;
#endif
	if (carry) /* subtracted */
		{
		if (!dif)
			/* error: a < b */
			return 0;
		while (dif)
			{
			dif--;
			t1 = *(ap++);
			t2 = (t1-1)&BN_MASK2;
			*(rp++) = t2;
			if (t1)
				break;
			}
		}
#if 0
	memcpy(rp,ap,sizeof(*rp)*(max-i));
#else
	if (rp != ap)
		{
		for (;;)
			{
			if (!dif--) break;
			rp[0]=ap[0];
			if (!dif--) break;
			rp[1]=ap[1];
			if (!dif--) break;
			rp[2]=ap[2];
			if (!dif--) break;
			rp[3]=ap[3];
			rp+=4;
			ap+=4;
			}
		}
#endif

	r->top=max;
	r->neg=0;
	bn_correct_top(r);
	return(1);
	}

int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
	{
	int max;
	int add=0,neg=0;
	const BIGNUM *tmp;

	bn_check_top(a);
	bn_check_top(b);

	/*  a -  b	a-b
	 *  a - -b	a+b
	 * -a -  b	-(a+b)
	 * -a - -b	b-a
	 */
	if (a->neg)
		{
		if (b->neg)
			{ tmp=a; a=b; b=tmp; }
		else
			{ add=1; neg=1; }
		}
	else
		{
		if (b->neg) { add=1; neg=0; }
		}

	if (add)
		{
		if (!BN_uadd(r,a,b)) return(0);
		r->neg=neg;
		return(1);
		}

	/* We are actually doing a - b :-) */

	max=(a->top > b->top)?a->top:b->top;
	if (bn_wexpand(r,max) == NULL) return(0);
	if (BN_ucmp(a,b) < 0)
		{
		if (!BN_usub(r,b,a)) return(0);
		r->neg=1;
		}
	else
		{
		if (!BN_usub(r,a,b)) return(0);
		r->neg=0;
		}
	bn_check_top(r);
	return(1);
	}
Commit	Line	Data
d02b48c6	1	/* crypto/bn/bn_add.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>
	60	#include "cryptlib.h"
	61	#include "bn_lcl.h"
	62
	63	/* r can == a or b */
dd8dec69	64	int BN_add(BIGNUM r, const BIGNUM a, const BIGNUM *b)
d02b48c6	65	{
dd8dec69	66	const BIGNUM *tmp;
380e145d	67	int a_neg = a->neg, ret;
d02b48c6	68
dfeab068 RE	69	bn_check_top(a);
	70	bn_check_top(b);
	71
d02b48c6 RE	72	/* a + b a+b
	73	* a + -b a-b
	74	* -a + b b-a
	75	* -a + -b -(a+b)
	76	*/
8dea52fa	77	if (a_neg ^ b->neg)
d02b48c6 RE	78	{
d02b48c6 RE	79	/* only one is negative */
8dea52fa	80	if (a_neg)
d02b48c6 RE	81	{ tmp=a; a=b; b=tmp; }
	82
	83	/* we are now a - b */
d02b48c6 RE	84
	85	if (BN_ucmp(a,b) < 0)
	86	{
dfeab068	87	if (!BN_usub(r,b,a)) return(0);
d02b48c6 RE	88	r->neg=1;
	89	}
	90	else
	91	{
dfeab068	92	if (!BN_usub(r,a,b)) return(0);
d02b48c6 RE	93	r->neg=0;
	94	}
	95	return(1);
	96	}
	97
380e145d UM	98	ret = BN_uadd(r,a,b);
380e145d UM	99	r->neg = a_neg;
d870740c	100	bn_check_top(r);
380e145d	101	return ret;
d02b48c6 RE	102	}
d02b48c6 RE	103
380e145d	104	/* unsigned add of b to a */
84c15db5	105	int BN_uadd(BIGNUM r, const BIGNUM a, const BIGNUM *b)
d02b48c6	106	{
6343829a	107	int max,min,dif;
380e145d	108	BN_ULONG ap,bp,*rp,carry,t1,t2;
84c15db5	109	const BIGNUM *tmp;
dfeab068 RE	110
	111	bn_check_top(a);
	112	bn_check_top(b);
d02b48c6	113
dfeab068 RE	114	if (a->top < b->top)
dfeab068 RE	115	{ tmp=a; a=b; b=tmp; }
380e145d UM	116	max = a->top;
	117	min = b->top;
	118	dif = max - min;
dfeab068 RE	119
dfeab068 RE	120	if (bn_wexpand(r,max+1) == NULL)
380e145d	121	return 0;
dfeab068	122
d02b48c6 RE	123	r->top=max;
d02b48c6 RE	124
dfeab068	125
d02b48c6 RE	126	ap=a->d;
	127	bp=b->d;
	128	rp=r->d;
58964a49 RE	129
	130	carry=bn_add_words(rp,ap,bp,min);
	131	rp+=min;
	132	ap+=min;
	133	bp+=min;
58964a49	134
d02b48c6 RE	135	if (carry)
d02b48c6 RE	136	{
380e145d	137	while (dif)
d02b48c6	138	{
380e145d UM	139	dif--;
	140	t1 = *(ap++);
	141	t2 = (t1+1) & BN_MASK2;
	142	*(rp++) = t2;
	143	if (t2)
58964a49 RE	144	{
	145	carry=0;
	146	break;
	147	}
d02b48c6	148	}
380e145d	149	if (carry)
d02b48c6	150	{
380e145d UM	151	/* carry != 0 => dif == 0 */
380e145d UM	152	*rp = 1;
d02b48c6 RE	153	r->top++;
	154	}
	155	}
380e145d UM	156	if (dif && rp != ap)
	157	while (dif--)
	158	/* copy remaining words if ap != rp */
	159	(rp++) = (ap++);
8dea52fa	160	r->neg = 0;
d870740c	161	bn_check_top(r);
380e145d	162	return 1;
dfeab068 RE	163	}
	164
	165	/* unsigned subtraction of b from a, a must be larger than b. */
84c15db5	166	int BN_usub(BIGNUM r, const BIGNUM a, const BIGNUM *b)
dfeab068	167	{
6343829a	168	int max,min,dif;
dfeab068 RE	169	register BN_ULONG t1,t2,ap,bp,*rp;
	170	int i,carry;
	171	#if defined(IRIX_CC_BUG) && !defined(LINT)
	172	int dummy;
	173	#endif
	174
	175	bn_check_top(a);
	176	bn_check_top(b);
	177
380e145d UM	178	max = a->top;
	179	min = b->top;
	180	dif = max - min;
	181
	182	if (dif < 0) /* hmm... should not be happening */
dfeab068 RE	183	{
	184	BNerr(BN_F_BN_USUB,BN_R_ARG2_LT_ARG3);
	185	return(0);
	186	}
	187
dfeab068 RE	188	if (bn_wexpand(r,max) == NULL) return(0);
	189
	190	ap=a->d;
	191	bp=b->d;
	192	rp=r->d;
	193
	194	#if 1
	195	carry=0;
380e145d	196	for (i = min; i != 0; i--)
dfeab068 RE	197	{
	198	t1= *(ap++);
	199	t2= *(bp++);
	200	if (carry)
	201	{
	202	carry=(t1 <= t2);
	203	t1=(t1-t2-1)&BN_MASK2;
	204	}
	205	else
	206	{
	207	carry=(t1 < t2);
	208	t1=(t1-t2)&BN_MASK2;
	209	}
	210	#if defined(IRIX_CC_BUG) && !defined(LINT)
	211	dummy=t1;
	212	#endif
	213	*(rp++)=t1&BN_MASK2;
	214	}
	215	#else
	216	carry=bn_sub_words(rp,ap,bp,min);
	217	ap+=min;
	218	bp+=min;
	219	rp+=min;
dfeab068 RE	220	#endif
	221	if (carry) /* subtracted */
	222	{
380e145d UM	223	if (!dif)
	224	/* error: a < b */
	225	return 0;
	226	while (dif)
dfeab068	227	{
380e145d UM	228	dif--;
	229	t1 = *(ap++);
	230	t2 = (t1-1)&BN_MASK2;
	231	*(rp++) = t2;
	232	if (t1)
	233	break;
dfeab068 RE	234	}
	235	}
	236	#if 0
	237	memcpy(rp,ap,sizeof(rp)(max-i));
	238	#else
	239	if (rp != ap)
	240	{
	241	for (;;)
	242	{
380e145d	243	if (!dif--) break;
dfeab068	244	rp[0]=ap[0];
380e145d	245	if (!dif--) break;
dfeab068	246	rp[1]=ap[1];
380e145d	247	if (!dif--) break;
dfeab068	248	rp[2]=ap[2];
380e145d	249	if (!dif--) break;
dfeab068 RE	250	rp[3]=ap[3];
	251	rp+=4;
	252	ap+=4;
	253	}
	254	}
	255	#endif
	256
	257	r->top=max;
8dea52fa	258	r->neg=0;
d870740c	259	bn_correct_top(r);
dfeab068 RE	260	return(1);
	261	}
	262
84c15db5	263	int BN_sub(BIGNUM r, const BIGNUM a, const BIGNUM *b)
dfeab068	264	{
6343829a	265	int max;
dfeab068	266	int add=0,neg=0;
84c15db5	267	const BIGNUM *tmp;
dfeab068 RE	268
	269	bn_check_top(a);
	270	bn_check_top(b);
	271
	272	/* a - b a-b
	273	* a - -b a+b
	274	* -a - b -(a+b)
	275	* -a - -b b-a
	276	*/
	277	if (a->neg)
	278	{
	279	if (b->neg)
	280	{ tmp=a; a=b; b=tmp; }
	281	else
	282	{ add=1; neg=1; }
	283	}
	284	else
	285	{
	286	if (b->neg) { add=1; neg=0; }
	287	}
	288
	289	if (add)
	290	{
	291	if (!BN_uadd(r,a,b)) return(0);
	292	r->neg=neg;
	293	return(1);
	294	}
	295
	296	/* We are actually doing a - b :-) */
	297
	298	max=(a->top > b->top)?a->top:b->top;
	299	if (bn_wexpand(r,max) == NULL) return(0);
	300	if (BN_ucmp(a,b) < 0)
	301	{
	302	if (!BN_usub(r,b,a)) return(0);
	303	r->neg=1;
	304	}
	305	else
	306	{
	307	if (!BN_usub(r,a,b)) return(0);
	308	r->neg=0;
	309	}
d870740c	310	bn_check_top(r);
dfeab068	311	return(1);
d02b48c6 RE	312	}
d02b48c6 RE	313