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1/* crypto/bn/bn_word.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 "cryptlib.h"
61#include "bn_lcl.h"
62
63BN_ULONG BN_mod_word(a, w)
64BIGNUM *a;
65unsigned long w;
66 {
67#ifndef BN_LLONG
68 BN_ULONG ret=0;
69#else
70 BN_ULLONG ret=0;
71#endif
72 int i;
73
74 w&=BN_MASK2;
75 for (i=a->top-1; i>=0; i--)
76 {
77#ifndef BN_LLONG
78 ret=((ret<<BN_BITS4)|((a->d[i]>>BN_BITS4)&BN_MASK2l))%(unsigned long)w;
79 ret=((ret<<BN_BITS4)|(a->d[i]&BN_MASK2l))%(unsigned long)w;
80#else
81 ret=(BN_ULLONG)(((ret<<(BN_ULLONG)BN_BITS2)|a->d[i])%
82 (BN_ULLONG)w);
83#endif
84 }
85 return((BN_ULONG)ret);
86 }
87
88BN_ULONG BN_div_word(a, w)
89BIGNUM *a;
90unsigned long w;
91 {
92 BN_ULONG ret;
93 int i;
94
95 if (a->top == 0) return(0);
96 ret=0;
97 w&=BN_MASK2;
98 for (i=a->top-1; i>=0; i--)
99 {
100 BN_ULONG l,d;
101
102 l=a->d[i];
103 d=bn_div64(ret,l,w);
104 ret=(l-((d*w)&BN_MASK2))&BN_MASK2;
105 a->d[i]=d;
106 }
107 if (a->d[a->top-1] == 0)
108 a->top--;
109 return(ret);
110 }
111
112int BN_add_word(a, w)
113BIGNUM *a;
114unsigned long w;
115 {
116 BN_ULONG l;
117 int i;
118
119 if (a->neg)
120 {
121 a->neg=0;
122 i=BN_sub_word(a,w);
123 if (!BN_is_zero(a))
124 a->neg=1;
125 return(i);
126 }
127 w&=BN_MASK2;
128 if (bn_wexpand(a,a->top+1) == NULL) return(0);
129 i=0;
130 for (;;)
131 {
132 l=(a->d[i]+(BN_ULONG)w)&BN_MASK2;
133 a->d[i]=l;
134 if (w > l)
135 w=1;
136 else
137 break;
138 i++;
139 }
140 if (i >= a->top)
141 a->top++;
142 return(1);
143 }
144
145int BN_sub_word(a, w)
146BIGNUM *a;
147unsigned long w;
148 {
149 int i;
150
151 if (a->neg)
152 {
153 a->neg=0;
154 i=BN_add_word(a,w);
155 a->neg=1;
156 return(i);
157 }
158
159 w&=BN_MASK2;
160 if ((a->top == 1) && (a->d[0] < w))
161 {
162 a->d[0]=w-a->d[0];
163 a->neg=1;
164 return(1);
165 }
166 i=0;
167 for (;;)
168 {
169 if (a->d[i] >= w)
170 {
171 a->d[i]-=w;
172 break;
173 }
174 else
175 {
176 a->d[i]=(a->d[i]-w)&BN_MASK2;
177 i++;
178 w=1;
179 }
180 }
181 if ((a->d[i] == 0) && (i == (a->top-1)))
182 a->top--;
183 return(1);
184 }
185
186int BN_mul_word(a,w)
187BIGNUM *a;
188unsigned long w;
189 {
190 BN_ULONG ll;
191
192 w&=BN_MASK2;
193 if (a->top)
194 {
195 ll=bn_mul_words(a->d,a->d,a->top,w);
196 if (ll)
197 {
198 if (bn_wexpand(a,a->top+1) == NULL) return(0);
199 a->d[a->top++]=ll;
200 }
201 }
202 return(0);
203 }
204
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