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(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         return(ret);
 106         }
 107
 108 int BN_add_word(BIGNUM *a, BN_ULONG w)
 109         {
 110         BN_ULONG l;
 111         int i;
 112
 113         if (a->neg)
 114                 {
 115                 a->neg=0;
 116                 i=BN_sub_word(a,w);
 117                 if (!BN_is_zero(a))
 118                         a->neg=1;
 119                 return(i);
 120                 }
 121         w&=BN_MASK2;
 122         if (bn_wexpand(a,a->top+1) == NULL) return(0);
 123         i=0;
 124         for (;;)
 125                 {
 126                 l=(a->d[i]+(BN_ULONG)w)&BN_MASK2;
 127                 a->d[i]=l;
 128                 if (w > l)
 129                         w=1;
 130                 else
 131                         break;
 132                 i++;
 133                 }
 134         if (i >= a->top)
 135                 a->top++;
 136         return(1);
 137         }
 138
 139 int BN_sub_word(BIGNUM *a, BN_ULONG w)
 140         {
 141         int i;
 142
 143         if (a->neg)
 144                 {
 145                 a->neg=0;
 146                 i=BN_add_word(a,w);
 147                 a->neg=1;
 148                 return(i);
 149                 }
 150
 151         w&=BN_MASK2;
 152         if ((a->top == 1) && (a->d[0] < w))
 153                 {
 154                 a->d[0]=w-a->d[0];
 155                 a->neg=1;
 156                 return(1);
 157                 }
 158         i=0;
 159         for (;;)
 160                 {
 161                 if (a->d[i] >= w)
 162                         {
 163                         a->d[i]-=w;
 164                         break;
 165                         }
 166                 else
 167                         {
 168                         a->d[i]=(a->d[i]-w)&BN_MASK2;
 169                         i++;
 170                         w=1;
 171                         }
 172                 }
 173         if ((a->d[i] == 0) && (i == (a->top-1)))
 174                 a->top--;
 175         return(1);
 176         }
 177
 178 int BN_mul_word(BIGNUM *a, BN_ULONG w)
 179         {
 180         BN_ULONG ll;
 181
 182         w&=BN_MASK2;
 183         if (a->top)
 184                 {
 185                 ll=bn_mul_words(a->d,a->d,a->top,w);
 186                 if (ll)
 187                         {
 188                         if (bn_wexpand(a,a->top+1) == NULL) return(0);
 189                         a->d[a->top++]=ll;
 190                         }
 191                 }
 192         return(1);
 193         }
 194