| 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 <string.h> |
| 61 | #include "bn_lcl.h" |
| 62 | |
| 63 | int BN_lshift(BIGNUM *r, const BIGNUM *a, int n) |
| 64 | { |
| 65 | int i,nw,lb,rb; |
| 66 | BN_ULONG *t,*f; |
| 67 | BN_ULONG l; |
| 68 | |
| 69 | r->neg=a->neg; |
| 70 | if (bn_wexpand(r,a->top+(n/BN_BITS2)+1) == NULL) return(0); |
| 71 | nw=n/BN_BITS2; |
| 72 | lb=n%BN_BITS2; |
| 73 | rb=BN_BITS2-lb; |
| 74 | f=a->d; |
| 75 | t=r->d; |
| 76 | t[a->top+nw]=0; |
| 77 | if (lb == 0) |
| 78 | for (i=a->top-1; i>=0; i--) |
| 79 | t[nw+i]=f[i]; |
| 80 | else |
| 81 | for (i=a->top-1; i>=0; i--) |
| 82 | { |
| 83 | l=f[i]; |
| 84 | t[nw+i+1]|=(l>>rb)&BN_MASK2; |
| 85 | t[nw+i]=(l<<lb)&BN_MASK2; |
| 86 | } |
| 87 | memset(t,0,nw*sizeof(t[0])); |
| 88 | /* for (i=0; i<nw; i++) |
| 89 | t[i]=0;*/ |
| 90 | r->top=a->top+nw+1; |
| 91 | bn_fix_top(r); |
| 92 | return(1); |
| 93 | } |
| 94 | |
| 95 | int BN_rshift(BIGNUM *r, BIGNUM *a, int n) |
| 96 | { |
| 97 | int i,j,nw,lb,rb; |
| 98 | BN_ULONG *t,*f; |
| 99 | BN_ULONG l,tmp; |
| 100 | |
| 101 | nw=n/BN_BITS2; |
| 102 | rb=n%BN_BITS2; |
| 103 | lb=BN_BITS2-rb; |
| 104 | if (nw > a->top || a->top == 0) |
| 105 | { |
| 106 | BN_zero(r); |
| 107 | return(1); |
| 108 | } |
| 109 | if (r != a) |
| 110 | { |
| 111 | r->neg=a->neg; |
| 112 | if (bn_wexpand(r,a->top-nw+1) == NULL) return(0); |
| 113 | } |
| 114 | |
| 115 | f= &(a->d[nw]); |
| 116 | t=r->d; |
| 117 | j=a->top-nw; |
| 118 | r->top=j; |
| 119 | |
| 120 | if (rb == 0) |
| 121 | { |
| 122 | for (i=j+1; i > 0; i--) |
| 123 | *(t++)= *(f++); |
| 124 | } |
| 125 | else |
| 126 | { |
| 127 | l= *(f++); |
| 128 | for (i=1; i<j; i++) |
| 129 | { |
| 130 | tmp =(l>>rb)&BN_MASK2; |
| 131 | l= *(f++); |
| 132 | *(t++) =(tmp|(l<<lb))&BN_MASK2; |
| 133 | } |
| 134 | *(t++) =(l>>rb)&BN_MASK2; |
| 135 | } |
| 136 | *t=0; |
| 137 | bn_fix_top(r); |
| 138 | return(1); |
| 139 | } |
| 140 | |
