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1 /* crypto/bn/bn_shift.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 | |
63 int BN_lshift1(BIGNUM *r, const BIGNUM *a) | |
64 { | |
65 register BN_ULONG *ap,*rp,t,c; | |
66 int i; | |
67 | |
68 bn_check_top(r); | |
69 bn_check_top(a); | |
70 | |
71 if (r != a) | |
72 { | |
73 r->neg=a->neg; | |
74 if (bn_wexpand(r,a->top+1) == NULL) return(0); | |
75 r->top=a->top; | |
76 } | |
77 else | |
78 { | |
79 if (bn_wexpand(r,a->top+1) == NULL) return(0); | |
80 } | |
81 ap=a->d; | |
82 rp=r->d; | |
83 c=0; | |
84 for (i=0; i<a->top; i++) | |
85 { | |
86 t= *(ap++); | |
87 *(rp++)=((t<<1)|c)&BN_MASK2; | |
88 c=(t & BN_TBIT)?1:0; | |
89 } | |
90 if (c) | |
91 { | |
92 *rp=1; | |
93 r->top++; | |
94 } | |
95 bn_check_top(r); | |
96 return(1); | |
97 } | |
98 | |
99 int BN_rshift1(BIGNUM *r, const BIGNUM *a) | |
100 { | |
101 BN_ULONG *ap,*rp,t,c; | |
102 int i,j; | |
103 | |
104 bn_check_top(r); | |
105 bn_check_top(a); | |
106 | |
107 if (BN_is_zero(a)) | |
108 { | |
109 BN_zero(r); | |
110 return(1); | |
111 } | |
112 i = a->top; | |
113 ap= a->d; | |
114 j = i-(ap[i-1]==1); | |
115 if (a != r) | |
116 { | |
117 if (bn_wexpand(r,j) == NULL) return(0); | |
118 r->neg=a->neg; | |
119 } | |
120 rp=r->d; | |
121 t=ap[--i]; | |
122 c=(t&1)?BN_TBIT:0; | |
123 if (t>>=1) rp[i]=t; | |
124 while (i>0) | |
125 { | |
126 t=ap[--i]; | |
127 rp[i]=((t>>1)&BN_MASK2)|c; | |
128 c=(t&1)?BN_TBIT:0; | |
129 } | |
130 r->top=j; | |
131 bn_check_top(r); | |
132 return(1); | |
133 } | |
134 | |
135 int BN_lshift(BIGNUM *r, const BIGNUM *a, int n) | |
136 { | |
137 int i,nw,lb,rb; | |
138 BN_ULONG *t,*f; | |
139 BN_ULONG l; | |
140 | |
141 bn_check_top(r); | |
142 bn_check_top(a); | |
143 | |
144 r->neg=a->neg; | |
145 nw=n/BN_BITS2; | |
146 if (bn_wexpand(r,a->top+nw+1) == NULL) return(0); | |
147 lb=n%BN_BITS2; | |
148 rb=BN_BITS2-lb; | |
149 f=a->d; | |
150 t=r->d; | |
151 t[a->top+nw]=0; | |
152 if (lb == 0) | |
153 for (i=a->top-1; i>=0; i--) | |
154 t[nw+i]=f[i]; | |
155 else | |
156 for (i=a->top-1; i>=0; i--) | |
157 { | |
158 l=f[i]; | |
159 t[nw+i+1]|=(l>>rb)&BN_MASK2; | |
160 t[nw+i]=(l<<lb)&BN_MASK2; | |
161 } | |
162 memset(t,0,nw*sizeof(t[0])); | |
163 /* for (i=0; i<nw; i++) | |
164 t[i]=0;*/ | |
165 r->top=a->top+nw+1; | |
166 bn_correct_top(r); | |
167 bn_check_top(r); | |
168 return(1); | |
169 } | |
170 | |
171 int BN_rshift(BIGNUM *r, const BIGNUM *a, int n) | |
172 { | |
173 int i,j,nw,lb,rb; | |
174 BN_ULONG *t,*f; | |
175 BN_ULONG l,tmp; | |
176 | |
177 bn_check_top(r); | |
178 bn_check_top(a); | |
179 | |
180 nw=n/BN_BITS2; | |
181 rb=n%BN_BITS2; | |
182 lb=BN_BITS2-rb; | |
183 if (nw >= a->top || a->top == 0) | |
184 { | |
185 BN_zero(r); | |
186 return(1); | |
187 } | |
188 i = (BN_num_bits(a)-n+(BN_BITS2-1))/BN_BITS2; | |
189 if (r != a) | |
190 { | |
191 r->neg=a->neg; | |
192 if (bn_wexpand(r,i) == NULL) return(0); | |
193 } | |
194 else | |
195 { | |
196 if (n == 0) | |
197 return 1; /* or the copying loop will go berserk */ | |
198 } | |
199 | |
200 f= &(a->d[nw]); | |
201 t=r->d; | |
202 j=a->top-nw; | |
203 r->top=i; | |
204 | |
205 if (rb == 0) | |
206 { | |
207 for (i=j; i != 0; i--) | |
208 *(t++)= *(f++); | |
209 } | |
210 else | |
211 { | |
212 l= *(f++); | |
213 for (i=j-1; i != 0; i--) | |
214 { | |
215 tmp =(l>>rb)&BN_MASK2; | |
216 l= *(f++); | |
217 *(t++) =(tmp|(l<<lb))&BN_MASK2; | |
218 } | |
219 if ((l = (l>>rb)&BN_MASK2)) *(t) = l; | |
220 } | |
221 bn_check_top(r); | |
222 return(1); | |
223 } | |
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