| 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 | } |
| 131 | |
