package/ead/src/tinysrp/bn_shift.c

   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         }