1 /* crypto/bn/bn_shift.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
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)"
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
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.]
63 int BN_lshift1(BIGNUM *r, const BIGNUM *a)
65 register BN_ULONG *ap, *rp, t, c;
73 if (bn_wexpand(r, a->top + 1) == NULL)
77 if (bn_wexpand(r, a->top + 1) == NULL)
83 for (i = 0; i < a->top; i++) {
85 *(rp++) = ((t << 1) | c) & BN_MASK2;
86 c = (t & BN_TBIT) ? 1 : 0;
96 int BN_rshift1(BIGNUM *r, const BIGNUM *a)
98 BN_ULONG *ap, *rp, t, c;
110 j = i - (ap[i - 1] == 1);
112 if (bn_wexpand(r, j) == NULL)
118 c = (t & 1) ? BN_TBIT : 0;
123 rp[i] = ((t >> 1) & BN_MASK2) | c;
124 c = (t & 1) ? BN_TBIT : 0;
131 int BN_lshift(BIGNUM *r, const BIGNUM *a, int n)
141 BNerr(BN_F_BN_LSHIFT, BN_R_INVALID_SHIFT);
147 if (bn_wexpand(r, a->top + nw + 1) == NULL)
155 for (i = a->top - 1; i >= 0; i--)
158 for (i = a->top - 1; i >= 0; i--) {
160 t[nw + i + 1] |= (l >> rb) & BN_MASK2;
161 t[nw + i] = (l << lb) & BN_MASK2;
163 memset(t, 0, nw * sizeof(t[0]));
165 * for (i=0; i<nw; i++) t[i]=0;
167 r->top = a->top + nw + 1;
173 int BN_rshift(BIGNUM *r, const BIGNUM *a, int n)
175 int i, j, nw, lb, rb;
183 BNerr(BN_F_BN_RSHIFT, BN_R_INVALID_SHIFT);
190 if (nw >= a->top || a->top == 0) {
194 i = (BN_num_bits(a) - n + (BN_BITS2 - 1)) / BN_BITS2;
197 if (bn_wexpand(r, i) == NULL)
201 return 1; /* or the copying loop will go berserk */
210 for (i = j; i != 0; i--)
214 for (i = j - 1; i != 0; i--) {
215 tmp = (l >> rb) & BN_MASK2;
217 *(t++) = (tmp | (l << lb)) & BN_MASK2;
219 if ((l = (l >> rb) & BN_MASK2))