package/ead/src/tinysrp/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 "bn_lcl.h"
  61
  62 int BN_add_word(BIGNUM *a, BN_ULONG w)
  63         {
  64         BN_ULONG l;
  65         int i;
  66
  67         if (a->neg)
  68                 {
  69                 a->neg=0;
  70                 i=BN_sub_word(a,w);
  71                 if (!BN_is_zero(a))
  72                         a->neg=!(a->neg);
  73                 return(i);
  74                 }
  75         w&=BN_MASK2;
  76         if (bn_wexpand(a,a->top+1) == NULL) return(0);
  77         i=0;
  78         for (;;)
  79                 {
  80                 l=(a->d[i]+(BN_ULONG)w)&BN_MASK2;
  81                 a->d[i]=l;
  82                 if (w > l)
  83                         w=1;
  84                 else
  85                         break;
  86                 i++;
  87                 }
  88         if (i >= a->top)
  89                 a->top++;
  90         return(1);
  91         }
  92
  93 int BN_sub_word(BIGNUM *a, BN_ULONG w)
  94         {
  95         int i;
  96
  97         if (BN_is_zero(a) || a->neg)
  98                 {
  99                 a->neg=0;
 100                 i=BN_add_word(a,w);
 101                 a->neg=1;
 102                 return(i);
 103                 }
 104
 105         w&=BN_MASK2;
 106         if ((a->top == 1) && (a->d[0] < w))
 107                 {
 108                 a->d[0]=w-a->d[0];
 109                 a->neg=1;
 110                 return(1);
 111                 }
 112         i=0;
 113         for (;;)
 114                 {
 115                 if (a->d[i] >= w)
 116                         {
 117                         a->d[i]-=w;
 118                         break;
 119                         }
 120                 else
 121                         {
 122                         a->d[i]=(a->d[i]-w)&BN_MASK2;
 123                         i++;
 124                         w=1;
 125                         }
 126                 }
 127         if ((a->d[i] == 0) && (i == (a->top-1)))
 128                 a->top--;
 129         return(1);
 130         }