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