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
63BN_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
86BN_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
108int 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=!(a->neg);
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		if (i >= a->top)
127			l=w;
128		else
129			l=(a->d[i]+(BN_ULONG)w)&BN_MASK2;
130		a->d[i]=l;
131		if (w > l)
132			w=1;
133		else
134			break;
135		i++;
136		}
137	if (i >= a->top)
138		a->top++;
139	return(1);
140	}
141
142int BN_sub_word(BIGNUM *a, BN_ULONG w)
143	{
144	int i;
145
146	if (BN_is_zero(a) || a->neg)
147		{
148		a->neg=0;
149		i=BN_add_word(a,w);
150		a->neg=1;
151		return(i);
152		}
153
154	w&=BN_MASK2;
155	if ((a->top == 1) && (a->d[0] < w))
156		{
157		a->d[0]=w-a->d[0];
158		a->neg=1;
159		return(1);
160		}
161	i=0;
162	for (;;)
163		{
164		if (a->d[i] >= w)
165			{
166			a->d[i]-=w;
167			break;
168			}
169		else
170			{
171			a->d[i]=(a->d[i]-w)&BN_MASK2;
172			i++;
173			w=1;
174			}
175		}
176	if ((a->d[i] == 0) && (i == (a->top-1)))
177		a->top--;
178	return(1);
179	}
180
181int BN_mul_word(BIGNUM *a, BN_ULONG w)
182	{
183	BN_ULONG ll;
184
185	w&=BN_MASK2;
186	if (a->top)
187		{
188		if (w == 0)
189			BN_zero(a);
190		else
191			{
192			ll=bn_mul_words(a->d,a->d,a->top,w);
193			if (ll)
194				{
195				if (bn_wexpand(a,a->top+1) == NULL) return(0);
196				a->d[a->top++]=ll;
197				}
198			}
199		}
200	return(1);
201	}
202
203