source: trunk/cscrypt/bn_add.c@ 3181

Last change on this file since 3181 was 3181, checked in by dingo35, 10 years ago

Adding threadsafety FIXMEs, feel free to join checking..

File size: 6.7 KB
Line 
1//FIXME Not checked on threadsafety yet; after checking please remove this line
2/* crypto/bn/bn_add.c */
3/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
4 * All rights reserved.
5 *
6 * This package is an SSL implementation written
7 * by Eric Young (eay@cryptsoft.com).
8 * The implementation was written so as to conform with Netscapes SSL.
9 *
10 * This library is free for commercial and non-commercial use as long as
11 * the following conditions are aheared to. The following conditions
12 * apply to all code found in this distribution, be it the RC4, RSA,
13 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
14 * included with this distribution is covered by the same copyright terms
15 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
16 *
17 * Copyright remains Eric Young's, and as such any Copyright notices in
18 * the code are not to be removed.
19 * If this package is used in a product, Eric Young should be given attribution
20 * as the author of the parts of the library used.
21 * This can be in the form of a textual message at program startup or
22 * in documentation (online or textual) provided with the package.
23 *
24 * Redistribution and use in source and binary forms, with or without
25 * modification, are permitted provided that the following conditions
26 * are met:
27 * 1. Redistributions of source code must retain the copyright
28 * notice, this list of conditions and the following disclaimer.
29 * 2. Redistributions in binary form must reproduce the above copyright
30 * notice, this list of conditions and the following disclaimer in the
31 * documentation and/or other materials provided with the distribution.
32 * 3. All advertising materials mentioning features or use of this software
33 * must display the following acknowledgement:
34 * "This product includes cryptographic software written by
35 * Eric Young (eay@cryptsoft.com)"
36 * The word 'cryptographic' can be left out if the rouines from the library
37 * being used are not cryptographic related :-).
38 * 4. If you include any Windows specific code (or a derivative thereof) from
39 * the apps directory (application code) you must include an acknowledgement:
40 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
41 *
42 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
43 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
44 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
45 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
46 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
47 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
48 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
49 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
50 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
51 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52 * SUCH DAMAGE.
53 *
54 * The licence and distribution terms for any publically available version or
55 * derivative of this code cannot be changed. i.e. this code cannot simply be
56 * copied and put under another distribution licence
57 * [including the GNU Public Licence.]
58 */
59
60#include <stdio.h>
61#include "openssl_mods.h"
62#include "bn_lcl.h"
63
64/* r can == a or b */
65int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
66 {
67 const BIGNUM *tmp;
68
69 bn_check_top(a);
70 bn_check_top(b);
71
72 /* a + b a+b
73 * a + -b a-b
74 * -a + b b-a
75 * -a + -b -(a+b)
76 */
77 if (a->neg ^ b->neg)
78 {
79 /* only one is negative */
80 if (a->neg)
81 { tmp=a; a=b; b=tmp; }
82
83 /* we are now a - b */
84
85 if (BN_ucmp(a,b) < 0)
86 {
87 if (!BN_usub(r,b,a)) return(0);
88 r->neg=1;
89 }
90 else
91 {
92 if (!BN_usub(r,a,b)) return(0);
93 r->neg=0;
94 }
95 return(1);
96 }
97
98 if (a->neg) /* both are neg */
99 r->neg=1;
100 else
101 r->neg=0;
102
103 if (!BN_uadd(r,a,b)) return(0);
104 return(1);
105 }
106
107/* unsigned add of b to a, r must be large enough */
108int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
109 {
110 register int i;
111 int max,min;
112 BN_ULONG *ap,*bp,*rp,carry,t1;
113 const BIGNUM *tmp;
114
115 bn_check_top(a);
116 bn_check_top(b);
117
118 if (a->top < b->top)
119 { tmp=a; a=b; b=tmp; }
120 max=a->top;
121 min=b->top;
122
123 if (bn_wexpand(r,max+1) == NULL)
124 return(0);
125
126 r->top=max;
127
128
129 ap=a->d;
130 bp=b->d;
131 rp=r->d;
132 carry=0;
133
134 carry=bn_add_words(rp,ap,bp,min);
135 rp+=min;
136 ap+=min;
137 bp+=min;
138 i=min;
139
140 if (carry)
141 {
142 while (i < max)
143 {
144 i++;
145 t1= *(ap++);
146 if ((*(rp++)=(t1+1)&BN_MASK2) >= t1)
147 {
148 carry=0;
149 break;
150 }
151 }
152 if ((i >= max) && carry)
153 {
154 *(rp++)=1;
155 r->top++;
156 }
157 }
158 if (rp != ap)
159 {
160 for (; i<max; i++)
161 *(rp++)= *(ap++);
162 }
163 /* memcpy(rp,ap,sizeof(*ap)*(max-i));*/
164 return(1);
165 }
166
167/* unsigned subtraction of b from a, a must be larger than b. */
168int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
169 {
170 int max,min;
171 register BN_ULONG t1,t2,*ap,*bp,*rp;
172 int i,carry;
173#if defined(IRIX_CC_BUG) && !defined(LINT)
174 int dummy;
175#endif
176
177 bn_check_top(a);
178 bn_check_top(b);
179
180 if (a->top < b->top) /* hmm... should not be happening */
181 {
182 return(0);
183 }
184
185 max=a->top;
186 min=b->top;
187 if (bn_wexpand(r,max) == NULL) return(0);
188
189 ap=a->d;
190 bp=b->d;
191 rp=r->d;
192
193#if 1
194 carry=0;
195 for (i=0; i<min; i++)
196 {
197 t1= *(ap++);
198 t2= *(bp++);
199 if (carry)
200 {
201 carry=(t1 <= t2);
202 t1=(t1-t2-1)&BN_MASK2;
203 }
204 else
205 {
206 carry=(t1 < t2);
207 t1=(t1-t2)&BN_MASK2;
208 }
209#if defined(IRIX_CC_BUG) && !defined(LINT)
210 dummy=t1;
211#endif
212 *(rp++)=t1&BN_MASK2;
213 }
214#else
215 carry=bn_sub_words(rp,ap,bp,min);
216 ap+=min;
217 bp+=min;
218 rp+=min;
219 i=min;
220#endif
221 if (carry) /* subtracted */
222 {
223 while (i < max)
224 {
225 i++;
226 t1= *(ap++);
227 t2=(t1-1)&BN_MASK2;
228 *(rp++)=t2;
229 if (t1 > t2) break;
230 }
231 }
232#if 0
233 memcpy(rp,ap,sizeof(*rp)*(max-i));
234#else
235 if (rp != ap)
236 {
237 for (;;)
238 {
239 if (i++ >= max) break;
240 rp[0]=ap[0];
241 if (i++ >= max) break;
242 rp[1]=ap[1];
243 if (i++ >= max) break;
244 rp[2]=ap[2];
245 if (i++ >= max) break;
246 rp[3]=ap[3];
247 rp+=4;
248 ap+=4;
249 }
250 }
251#endif
252
253 r->top=max;
254 bn_fix_top(r);
255 return(1);
256 }
257
258int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
259 {
260 int max;
261 int add=0,neg=0;
262 const BIGNUM *tmp;
263
264 bn_check_top(a);
265 bn_check_top(b);
266
267 /* a - b a-b
268 * a - -b a+b
269 * -a - b -(a+b)
270 * -a - -b b-a
271 */
272 if (a->neg)
273 {
274 if (b->neg)
275 { tmp=a; a=b; b=tmp; }
276 else
277 { add=1; neg=1; }
278 }
279 else
280 {
281 if (b->neg) { add=1; neg=0; }
282 }
283
284 if (add)
285 {
286 if (!BN_uadd(r,a,b)) return(0);
287 r->neg=neg;
288 return(1);
289 }
290
291 /* We are actually doing a - b :-) */
292
293 max=(a->top > b->top)?a->top:b->top;
294 if (bn_wexpand(r,max) == NULL) return(0);
295 if (BN_ucmp(a,b) < 0)
296 {
297 if (!BN_usub(r,b,a)) return(0);
298 r->neg=1;
299 }
300 else
301 {
302 if (!BN_usub(r,a,b)) return(0);
303 r->neg=0;
304 }
305 return(1);
306 }
307
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