bn_mul.c revision 1.1 
1/* crypto/bn/bn_mul.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/* r must be different to a and b */
64/* int BN_mmul(r, a, b) */
65int BN_mul(r, a, b)
66BIGNUM *r;
67BIGNUM *a;
68BIGNUM *b;
69	{
70	int i;
71	int max,al,bl;
72	BN_ULONG *ap,*bp,*rp;
73
74	al=a->top;
75	bl=b->top;
76	if ((al == 0) || (bl == 0))
77		{
78		r->top=0;
79		return(1);
80		}
81
82	max=(al+bl);
83	if (bn_wexpand(r,max) == NULL) return(0);
84	r->top=max;
85	r->neg=a->neg^b->neg;
86	ap=a->d;
87	bp=b->d;
88	rp=r->d;
89
90	rp[al]=bn_mul_words(rp,ap,al,*(bp++));
91	rp++;
92	for (i=1; i<bl; i++)
93		{
94		rp[al]=bn_mul_add_words(rp,ap,al,*(bp++));
95		rp++;
96		}
97	if (r->d[max-1] == 0) r->top--;
98	return(1);
99	}
100
101#if 0
102#include "stack.h"
103
104int limit=16;
105
106typedef struct bn_pool_st
107	{
108	int used;
109	int tos;
110	STACK *sk;
111	} BN_POOL;
112
113BIGNUM *BN_POOL_push(bp)
114BN_POOL *bp;
115	{
116	BIGNUM *ret;
117
118	if (bp->used >= bp->tos)
119		{
120		ret=BN_new();
121		sk_push(bp->sk,(char *)ret);
122		bp->tos++;
123		bp->used++;
124		}
125	else
126		{
127		ret=(BIGNUM *)sk_value(bp->sk,bp->used);
128		bp->used++;
129		}
130	return(ret);
131	}
132
133void BN_POOL_pop(bp,num)
134BN_POOL *bp;
135int num;
136	{
137	bp->used-=num;
138	}
139
140int BN_mul(r,a,b)
141BIGNUM *r,*a,*b;
142	{
143	static BN_POOL bp;
144	static init=1;
145
146	if (init)
147		{
148		bp.used=0;
149		bp.tos=0;
150		bp.sk=sk_new_null();
151		init=0;
152		}
153	return(BN_mm(r,a,b,&bp));
154	}
155
156/* r must be different to a and b */
157int BN_mm(m, A, B, bp)
158BIGNUM *m,*A,*B;
159BN_POOL *bp;
160	{
161	int i,num;
162	int an,bn;
163	BIGNUM *a,*b,*c,*d,*ac,*bd;
164
165	an=A->top;
166	bn=B->top;
167	if ((an <= limit) || (bn <= limit))
168		{
169		return(BN_mmul(m,A,B));
170		}
171
172	a=BN_POOL_push(bp);
173	b=BN_POOL_push(bp);
174	c=BN_POOL_push(bp);
175	d=BN_POOL_push(bp);
176	ac=BN_POOL_push(bp);
177	bd=BN_POOL_push(bp);
178
179	num=(an <= bn)?an:bn;
180	num=1<<(BN_num_bits_word(num-1)-1);
181
182	/* Are going to now chop things into 'num' word chunks. */
183	num*=BN_BITS2;
184
185	BN_copy(a,A);
186	BN_mask_bits(a,num);
187	BN_rshift(b,A,num);
188
189	BN_copy(c,B);
190	BN_mask_bits(c,num);
191	BN_rshift(d,B,num);
192
193	BN_sub(ac ,b,a);
194	BN_sub(bd,c,d);
195	BN_mm(m,ac,bd,bp);
196	BN_mm(ac,a,c,bp);
197	BN_mm(bd,b,d,bp);
198
199	BN_add(m,m,ac);
200	BN_add(m,m,bd);
201	BN_lshift(m,m,num);
202	BN_lshift(bd,bd,num*2);
203
204	BN_add(m,m,ac);
205	BN_add(m,m,bd);
206	BN_POOL_pop(bp,6);
207	return(1);
208	}
209#endif
210