1 /* $OpenBSD: bn_add.c,v 1.13 2018/07/23 18:07:21 tb Exp $ */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
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)"
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
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.]
61 #include <openssl/err.h>
66 BN_add(BIGNUM
*r
, const BIGNUM
*a
, const BIGNUM
*b
)
73 if (a
->neg
== b
->neg
) {
75 ret
= BN_uadd(r
, a
, b
);
77 int cmp
= BN_ucmp(a
, b
);
81 ret
= BN_usub(r
, a
, b
);
84 ret
= BN_usub(r
, b
, a
);
98 BN_uadd(BIGNUM
*r
, const BIGNUM
*a
, const BIGNUM
*b
)
101 const BN_ULONG
*ap
, *bp
;
102 BN_ULONG
*rp
, carry
, t1
, t2
;
107 if (a
->top
< b
->top
) {
118 if (bn_wexpand(r
, max
+ 1) == NULL
)
127 carry
= bn_add_words(rp
, ap
, bp
, min
);
134 t2
= (t1
+ carry
) & BN_MASK2
;
147 BN_usub(BIGNUM
*r
, const BIGNUM
*a
, const BIGNUM
*b
)
150 const BN_ULONG
*ap
, *bp
;
151 BN_ULONG t1
, t2
, borrow
, *rp
;
161 BNerror(BN_R_ARG2_LT_ARG3
);
165 if (bn_wexpand(r
, max
) == NULL
)
172 borrow
= bn_sub_words(rp
, ap
, bp
, min
);
179 t2
= (t1
- borrow
) & BN_MASK2
;
184 while (max
> 0 && *--rp
== 0)
194 BN_sub(BIGNUM
*r
, const BIGNUM
*a
, const BIGNUM
*b
)
201 if (a
->neg
!= b
->neg
) {
203 ret
= BN_uadd(r
, a
, b
);
205 int cmp
= BN_ucmp(a
, b
);
209 ret
= BN_usub(r
, a
, b
);
210 } else if (cmp
< 0) {
212 ret
= BN_usub(r
, b
, a
);