rdesktop/crypto/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 "bn_lcl.h"

/* r can == a or b */
int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
        {
        const BIGNUM *tmp;

        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);
                }

        if (a->neg) /* both are neg */
                r->neg=1;
        else
                r->neg=0;

        if (!BN_uadd(r,a,b)) return(0);
        return(1);
        }

/* unsigned add of b to a, r must be large enough */
int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
        {
        register int i;
        int max,min;
        BN_ULONG *ap,*bp,*rp,carry,t1;
        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;

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

        r->top=max;


        ap=a->d;
        bp=b->d;
        rp=r->d;
        carry=0;

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

        if (carry)
                {
                while (i < max)
                        {
                        i++;
                        t1= *(ap++);
                        if ((*(rp++)=(t1+1)&BN_MASK2) >= t1)
                                {
                                carry=0;
                                break;
                                }
                        }
                if ((i >= max) && carry)
                        {
                        *(rp++)=1;
                        r->top++;
                        }
                }
        if (rp != ap)
                {
                for (; i<max; i++)
                        *(rp++)= *(ap++);
                }
        /* memcpy(rp,ap,sizeof(*ap)*(max-i));*/
        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;
        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);

        if (a->top < b->top) /* hmm... should not be happening */
                {
                BNerr(BN_F_BN_USUB,BN_R_ARG2_LT_ARG3);
                return(0);
                }

        max=a->top;
        min=b->top;
        if (bn_wexpand(r,max) == NULL) return(0);

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

#if 1
        carry=0;
        for (i=0; i<min; 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;
        i=min;
#endif
        if (carry) /* subtracted */
                {
                while (i < max)
                        {
                        i++;
                        t1= *(ap++);
                        t2=(t1-1)&BN_MASK2;
                        *(rp++)=t2;
                        if (t1 > t2) break;
                        }
                }
#if 0
        memcpy(rp,ap,sizeof(*rp)*(max-i));
#else
        if (rp != ap)
                {
                for (;;)
                        {
                        if (i++ >= max) break;
                        rp[0]=ap[0];
                        if (i++ >= max) break;
                        rp[1]=ap[1];
                        if (i++ >= max) break;
                        rp[2]=ap[2];
                        if (i++ >= max) break;
                        rp[3]=ap[3];
                        rp+=4;
                        ap+=4;
                        }
                }
#endif

        r->top=max;
        bn_fix_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;
                }
        return(1);
        }

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