1 /* crypto/bn/bn_shift.c */ 2 /* Copyright (C) 1995-1998 Eric Young (eay (at) cryptsoft.com) 3 * All rights reserved. 4 * 5 * This package is an SSL implementation written 6 * by Eric Young (eay (at) 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 (at) 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 (at) 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 (at) 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 } 224
