1 /* crypto/bn/bn_word.c */
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.]
63 BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w)
74 for (i=a->top-1; i>=0; i--)
77 ret=((ret<<BN_BITS4)|((a->d[i]>>BN_BITS4)&BN_MASK2l))%w;
78 ret=((ret<<BN_BITS4)|(a->d[i]&BN_MASK2l))%w;
80 ret=(BN_ULLONG)(((ret<<(BN_ULLONG)BN_BITS2)|a->d[i])%
84 return((BN_ULONG)ret);
87 BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w)
96 /* actually this an error (division by zero) */
101 /* normalize input (so bn_div_words doesn't complain) */
102 j = BN_BITS2 - BN_num_bits_word(w);
104 if (!BN_lshift(a, a, j))
107 for (i=a->top-1; i>=0; i--)
112 d=bn_div_words(ret,l,w);
113 ret=(l-((d*w)&BN_MASK2))&BN_MASK2;
116 if ((a->top > 0) && (a->d[a->top-1] == 0))
123 int BN_add_word(BIGNUM *a, BN_ULONG w)
131 /* degenerate case: w is zero */
133 /* degenerate case: a is zero */
134 if(BN_is_zero(a)) return BN_set_word(a, w);
135 /* handle 'a' when negative */
144 /* Only expand (and risk failing) if it's possibly necessary */
145 if (((BN_ULONG)(a->d[a->top - 1] + 1) == 0) &&
146 (bn_wexpand(a,a->top+1) == NULL))
154 l=(a->d[i]+w)&BN_MASK2;
168 int BN_sub_word(BIGNUM *a, BN_ULONG w)
175 /* degenerate case: w is zero */
177 /* degenerate case: a is zero */
178 if(BN_is_zero(a)) return BN_set_word(a,w);
179 /* handle 'a' when negative */
188 if ((a->top == 1) && (a->d[0] < w))
204 a->d[i]=(a->d[i]-w)&BN_MASK2;
209 if ((a->d[i] == 0) && (i == (a->top-1)))
215 int BN_mul_word(BIGNUM *a, BN_ULONG w)
227 ll=bn_mul_words(a->d,a->d,a->top,w);
230 if (bn_wexpand(a,a->top+1) == NULL) return(0);