crypto/bn/bn_word.c

   1 /* crypto/bn/bn_word.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
  63 BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w)
  64         {
  65 #ifndef BN_LLONG
  66         BN_ULONG ret=0;
  67 #else
  68         BN_ULLONG ret=0;
  69 #endif
  70         int i;
  71
  72         w&=BN_MASK2;
  73         for (i=a->top-1; i>=0; i--)
  74                 {
  75 #ifndef BN_LLONG
  76                 ret=((ret<<BN_BITS4)|((a->d[i]>>BN_BITS4)&BN_MASK2l))%w;
  77                 ret=((ret<<BN_BITS4)|(a->d[i]&BN_MASK2l))%w;
  78 #else
  79                 ret=(BN_ULLONG)(((ret<<(BN_ULLONG)BN_BITS2)|a->d[i])%
  80                         (BN_ULLONG)w);
  81 #endif
  82                 }
  83         return((BN_ULONG)ret);
  84         }
  85
  86 BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w)
  87         {
  88         BN_ULONG ret;
  89         int i;
  90
  91         if (a->top == 0) return(0);
  92         ret=0;
  93         w&=BN_MASK2;
  94         for (i=a->top-1; i>=0; i--)
  95                 {
  96                 BN_ULONG l,d;
  97
  98                 l=a->d[i];
  99                 d=bn_div_words(ret,l,w);
 100                 ret=(l-((d*w)&BN_MASK2))&BN_MASK2;
 101                 a->d[i]=d;
 102                 }
 103         if ((a->top > 0) && (a->d[a->top-1] == 0))
 104                 a->top--;
 105         bn_check_top(a);
 106         return(ret);
 107         }
 108
 109 int BN_add_word(BIGNUM *a, BN_ULONG w)
 110         {
 111         BN_ULONG l;
 112         int i;
 113
 114         if (a->neg)
 115                 {
 116                 a->neg=0;
 117                 i=BN_sub_word(a,w);
 118                 if (!BN_is_zero(a))
 119                         a->neg=!(a->neg);
 120                 return(i);
 121                 }
 122         w&=BN_MASK2;
 123         if (bn_wexpand(a,a->top+1) == NULL) return(0);
 124         i=0;
 125         for (;;)
 126                 {
 127                 if (i >= a->top)
 128                         l=w;
 129                 else
 130                         l=(a->d[i]+(BN_ULONG)w)&BN_MASK2;
 131                 a->d[i]=l;
 132                 if (w > l)
 133                         w=1;
 134                 else
 135                         break;
 136                 i++;
 137                 }
 138         if (i >= a->top)
 139                 a->top++;
 140         bn_check_top(a);
 141         return(1);
 142         }
 143
 144 int BN_sub_word(BIGNUM *a, BN_ULONG w)
 145         {
 146         int i;
 147
 148         if (BN_is_zero(a) || a->neg)
 149                 {
 150                 a->neg=0;
 151                 i=BN_add_word(a,w);
 152                 a->neg=1;
 153                 return(i);
 154                 }
 155
 156         w&=BN_MASK2;
 157         if ((a->top == 1) && (a->d[0] < w))
 158                 {
 159                 a->d[0]=w-a->d[0];
 160                 a->neg=1;
 161                 return(1);
 162                 }
 163         i=0;
 164         for (;;)
 165                 {
 166                 if (a->d[i] >= w)
 167                         {
 168                         a->d[i]-=w;
 169                         break;
 170                         }
 171                 else
 172                         {
 173                         a->d[i]=(a->d[i]-w)&BN_MASK2;
 174                         i++;
 175                         w=1;
 176                         }
 177                 }
 178         if ((a->d[i] == 0) && (i == (a->top-1)))
 179                 a->top--;
 180         bn_check_top(a);
 181         return(1);
 182         }
 183
 184 int BN_mul_word(BIGNUM *a, BN_ULONG w)
 185         {
 186         BN_ULONG ll;
 187
 188         w&=BN_MASK2;
 189         if (a->top)
 190                 {
 191                 if (w == 0)
 192                         BN_zero(a);
 193                 else
 194                         {
 195                         ll=bn_mul_words(a->d,a->d,a->top,w);
 196                         if (ll)
 197                                 {
 198                                 if (bn_wexpand(a,a->top+1) == NULL) return(0);
 199                                 a->d[a->top++]=ll;
 200                                 }
 201                         }
 202                 }
 203         bn_check_top(a);
 204         return(1);
 205         }
 206