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 63int 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 99int BN_rshift1(BIGNUM *r, const BIGNUM *a) 100 { 101 BN_ULONG *ap,*rp,t,c; 102 int i; 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 if (a != r) 113 { 114 if (bn_wexpand(r,a->top) == NULL) return(0); 115 r->top=a->top; 116 r->neg=a->neg; 117 } 118 ap=a->d; 119 rp=r->d; 120 c=0; 121 for (i=a->top-1; i>=0; i--) 122 { 123 t=ap[i]; 124 rp[i]=((t>>1)&BN_MASK2)|c; 125 c=(t&1)?BN_TBIT:0; 126 } 127 bn_correct_top(r); 128 bn_check_top(r); 129 return(1); 130 } 131 132int BN_lshift(BIGNUM *r, const BIGNUM *a, int n) 133 { 134 int i,nw,lb,rb; 135 BN_ULONG *t,*f; 136 BN_ULONG l; 137 138 bn_check_top(r); 139 bn_check_top(a); 140 141 r->neg=a->neg; 142 nw=n/BN_BITS2; 143 if (bn_wexpand(r,a->top+nw+1) == NULL) return(0); 144 lb=n%BN_BITS2; 145 rb=BN_BITS2-lb; 146 f=a->d; 147 t=r->d; 148 t[a->top+nw]=0; 149 if (lb == 0) 150 for (i=a->top-1; i>=0; i--) 151 t[nw+i]=f[i]; 152 else 153 for (i=a->top-1; i>=0; i--) 154 { 155 l=f[i]; 156 t[nw+i+1]|=(l>>rb)&BN_MASK2; 157 t[nw+i]=(l<<lb)&BN_MASK2; 158 } 159 memset(t,0,nw*sizeof(t[0])); 160/* for (i=0; i<nw; i++) 161 t[i]=0;*/ 162 r->top=a->top+nw+1; 163 bn_correct_top(r); 164 bn_check_top(r); 165 return(1); 166 } 167 168int BN_rshift(BIGNUM *r, const BIGNUM *a, int n) 169 { 170 int i,j,nw,lb,rb; 171 BN_ULONG *t,*f; 172 BN_ULONG l,tmp; 173 174 bn_check_top(r); 175 bn_check_top(a); 176 177 nw=n/BN_BITS2; 178 rb=n%BN_BITS2; 179 lb=BN_BITS2-rb; 180 if (nw >= a->top || a->top == 0) 181 { 182 BN_zero(r); 183 return(1); 184 } 185 if (r != a) 186 { 187 r->neg=a->neg; 188 if (bn_wexpand(r,a->top-nw+1) == NULL) return(0); 189 } 190 else 191 { 192 if (n == 0) 193 return 1; /* or the copying loop will go berserk */ 194 } 195 196 f= &(a->d[nw]); 197 t=r->d; 198 j=a->top-nw; 199 r->top=j; 200 201 if (rb == 0) 202 { 203 for (i=j; i != 0; i--) 204 *(t++)= *(f++); 205 } 206 else 207 { 208 l= *(f++); 209 for (i=j-1; i != 0; i--) 210 { 211 tmp =(l>>rb)&BN_MASK2; 212 l= *(f++); 213 *(t++) =(tmp|(l<<lb))&BN_MASK2; 214 } 215 *(t++) =(l>>rb)&BN_MASK2; 216 } 217 bn_correct_top(r); 218 bn_check_top(r); 219 return(1); 220 } 221