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
BN_mod_word(const BIGNUM * a,BN_ULONG w)63 BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w)
64 {
65 #ifndef BN_LLONG
66 BN_ULONG ret=0;
67 #else
68 BN_ULLONG ret=0;
69 #endif
70 int i;
71
72 w&=BN_MASK2;
73 for (i=a->top-1; i>=0; i--)
74 {
75 #ifndef BN_LLONG
76 ret=((ret<<BN_BITS4)|((a->d[i]>>BN_BITS4)&BN_MASK2l))%w;
77 ret=((ret<<BN_BITS4)|(a->d[i]&BN_MASK2l))%w;
78 #else
79 ret=(BN_ULLONG)(((ret<<(BN_ULLONG)BN_BITS2)|a->d[i])%
80 (BN_ULLONG)w);
81 #endif
82 }
83 return((BN_ULONG)ret);
84 }
85
BN_div_word(BIGNUM * a,BN_ULONG w)86 BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w)
87 {
88 BN_ULONG ret;
89 int i;
90
91 if (a->top == 0) return(0);
92 ret=0;
93 w&=BN_MASK2;
94 for (i=a->top-1; i>=0; i--)
95 {
96 BN_ULONG l,d;
97
98 l=a->d[i];
99 d=bn_div_words(ret,l,w);
100 ret=(l-((d*w)&BN_MASK2))&BN_MASK2;
101 a->d[i]=d;
102 }
103 if ((a->top > 0) && (a->d[a->top-1] == 0))
104 a->top--;
105 return(ret);
106 }
107
BN_add_word(BIGNUM * a,BN_ULONG w)108 int BN_add_word(BIGNUM *a, BN_ULONG w)
109 {
110 BN_ULONG l;
111 int i;
112
113 if ((w & BN_MASK2) == 0)
114 return(1);
115
116 if (a->neg)
117 {
118 a->neg=0;
119 i=BN_sub_word(a,w);
120 if (!BN_is_zero(a))
121 a->neg=!(a->neg);
122 return(i);
123 }
124 w&=BN_MASK2;
125 if (bn_wexpand(a,a->top+1) == NULL) return(0);
126 i=0;
127 for (;;)
128 {
129 if (i >= a->top)
130 l=w;
131 else
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
BN_sub_word(BIGNUM * a,BN_ULONG w)145 int BN_sub_word(BIGNUM *a, BN_ULONG w)
146 {
147 int i;
148
149 if ((w & BN_MASK2) == 0)
150 return(1);
151
152 if (BN_is_zero(a) || a->neg)
153 {
154 a->neg=0;
155 i=BN_add_word(a,w);
156 a->neg=1;
157 return(i);
158 }
159
160 w&=BN_MASK2;
161 if ((a->top == 1) && (a->d[0] < w))
162 {
163 a->d[0]=w-a->d[0];
164 a->neg=1;
165 return(1);
166 }
167 i=0;
168 for (;;)
169 {
170 if (a->d[i] >= w)
171 {
172 a->d[i]-=w;
173 break;
174 }
175 else
176 {
177 a->d[i]=(a->d[i]-w)&BN_MASK2;
178 i++;
179 w=1;
180 }
181 }
182 if ((a->d[i] == 0) && (i == (a->top-1)))
183 a->top--;
184 return(1);
185 }
186
BN_mul_word(BIGNUM * a,BN_ULONG w)187 int BN_mul_word(BIGNUM *a, BN_ULONG w)
188 {
189 BN_ULONG ll;
190
191 w&=BN_MASK2;
192 if (a->top)
193 {
194 if (w == 0)
195 BN_zero(a);
196 else
197 {
198 ll=bn_mul_words(a->d,a->d,a->top,w);
199 if (ll)
200 {
201 if (bn_wexpand(a,a->top+1) == NULL) return(0);
202 a->d[a->top++]=ll;
203 }
204 }
205 }
206 return(1);
207 }
208
209