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(a, w) 64 BIGNUM *a; 65 unsigned long w; 66 { 67 #ifndef BN_LLONG 68 BN_ULONG ret=0; 69 #else 70 BN_ULLONG ret=0; 71 #endif 72 int i; 73 74 w&=BN_MASK2; 75 for (i=a->top-1; i>=0; i--) 76 { 77 #ifndef BN_LLONG 78 ret=((ret<<BN_BITS4)|((a->d[i]>>BN_BITS4)&BN_MASK2l))%(unsigned long)w; 79 ret=((ret<<BN_BITS4)|(a->d[i]&BN_MASK2l))%(unsigned long)w; 80 #else 81 ret=(BN_ULLONG)(((ret<<(BN_ULLONG)BN_BITS2)|a->d[i])% 82 (BN_ULLONG)w); 83 #endif 84 } 85 return((BN_ULONG)ret); 86 } 87 88 BN_ULONG BN_div_word(a, w) 89 BIGNUM *a; 90 unsigned long w; 91 { 92 BN_ULONG ret; 93 int i; 94 95 if (a->top == 0) return(0); 96 ret=0; 97 w&=BN_MASK2; 98 for (i=a->top-1; i>=0; i--) 99 { 100 BN_ULONG l,d; 101 102 l=a->d[i]; 103 d=bn_div64(ret,l,w); 104 ret=(l-((d*w)&BN_MASK2))&BN_MASK2; 105 a->d[i]=d; 106 } 107 if (a->d[a->top-1] == 0) 108 a->top--; 109 return(ret); 110 } 111 112 int BN_add_word(a, w) 113 BIGNUM *a; 114 unsigned long w; 115 { 116 BN_ULONG l; 117 int i; 118 119 if (a->neg) 120 { 121 a->neg=0; 122 i=BN_sub_word(a,w); 123 if (!BN_is_zero(a)) 124 a->neg=1; 125 return(i); 126 } 127 w&=BN_MASK2; 128 if (bn_wexpand(a,a->top+1) == NULL) return(0); 129 i=0; 130 for (;;) 131 { 132 l=(a->d[i]+(BN_ULONG)w)&BN_MASK2; 133 a->d[i]=l; 134 if (w > l) 135 w=1; 136 else 137 break; 138 i++; 139 } 140 if (i >= a->top) 141 a->top++; 142 return(1); 143 } 144 145 int BN_sub_word(a, w) 146 BIGNUM *a; 147 unsigned long w; 148 { 149 int i; 150 151 if (a->neg) 152 { 153 a->neg=0; 154 i=BN_add_word(a,w); 155 a->neg=1; 156 return(i); 157 } 158 159 w&=BN_MASK2; 160 if ((a->top == 1) && (a->d[0] < w)) 161 { 162 a->d[0]=w-a->d[0]; 163 a->neg=1; 164 return(1); 165 } 166 i=0; 167 for (;;) 168 { 169 if (a->d[i] >= w) 170 { 171 a->d[i]-=w; 172 break; 173 } 174 else 175 { 176 a->d[i]=(a->d[i]-w)&BN_MASK2; 177 i++; 178 w=1; 179 } 180 } 181 if ((a->d[i] == 0) && (i == (a->top-1))) 182 a->top--; 183 return(1); 184 } 185 186 int BN_mul_word(a,w) 187 BIGNUM *a; 188 unsigned long w; 189 { 190 BN_ULONG ll; 191 192 w&=BN_MASK2; 193 if (a->top) 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 return(0); 203 } 204 205