| /* crypto/bn/bn_shift.c */ |
| /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
| * All rights reserved. |
| * |
| * This package is an SSL implementation written |
| * by Eric Young (eay@cryptsoft.com). |
| * The implementation was written so as to conform with Netscapes SSL. |
| * |
| * This library is free for commercial and non-commercial use as long as |
| * the following conditions are aheared to. The following conditions |
| * apply to all code found in this distribution, be it the RC4, RSA, |
| * lhash, DES, etc., code; not just the SSL code. The SSL documentation |
| * included with this distribution is covered by the same copyright terms |
| * except that the holder is Tim Hudson (tjh@cryptsoft.com). |
| * |
| * Copyright remains Eric Young's, and as such any Copyright notices in |
| * the code are not to be removed. |
| * If this package is used in a product, Eric Young should be given attribution |
| * as the author of the parts of the library used. |
| * This can be in the form of a textual message at program startup or |
| * in documentation (online or textual) provided with the package. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. All advertising materials mentioning features or use of this software |
| * must display the following acknowledgement: |
| * "This product includes cryptographic software written by |
| * Eric Young (eay@cryptsoft.com)" |
| * The word 'cryptographic' can be left out if the rouines from the library |
| * being used are not cryptographic related :-). |
| * 4. If you include any Windows specific code (or a derivative thereof) from |
| * the apps directory (application code) you must include an acknowledgement: |
| * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" |
| * |
| * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * |
| * The licence and distribution terms for any publically available version or |
| * derivative of this code cannot be changed. i.e. this code cannot simply be |
| * copied and put under another distribution licence |
| * [including the GNU Public Licence.] |
| */ |
| |
| #include <stdio.h> |
| #include "cryptlib.h" |
| #include "bn_lcl.h" |
| |
| int BN_lshift1(BIGNUM *r, const BIGNUM *a) |
| { |
| register BN_ULONG *ap, *rp, t, c; |
| int i; |
| |
| bn_check_top(r); |
| bn_check_top(a); |
| |
| if (r != a) { |
| r->neg = a->neg; |
| if (bn_wexpand(r, a->top + 1) == NULL) |
| return (0); |
| r->top = a->top; |
| } else { |
| if (bn_wexpand(r, a->top + 1) == NULL) |
| return (0); |
| } |
| ap = a->d; |
| rp = r->d; |
| c = 0; |
| for (i = 0; i < a->top; i++) { |
| t = *(ap++); |
| *(rp++) = ((t << 1) | c) & BN_MASK2; |
| c = (t & BN_TBIT) ? 1 : 0; |
| } |
| if (c) { |
| *rp = 1; |
| r->top++; |
| } |
| bn_check_top(r); |
| return (1); |
| } |
| |
| int BN_rshift1(BIGNUM *r, const BIGNUM *a) |
| { |
| BN_ULONG *ap, *rp, t, c; |
| int i, j; |
| |
| bn_check_top(r); |
| bn_check_top(a); |
| |
| if (BN_is_zero(a)) { |
| BN_zero(r); |
| return (1); |
| } |
| i = a->top; |
| ap = a->d; |
| j = i - (ap[i - 1] == 1); |
| if (a != r) { |
| if (bn_wexpand(r, j) == NULL) |
| return (0); |
| r->neg = a->neg; |
| } |
| rp = r->d; |
| t = ap[--i]; |
| c = (t & 1) ? BN_TBIT : 0; |
| if (t >>= 1) |
| rp[i] = t; |
| while (i > 0) { |
| t = ap[--i]; |
| rp[i] = ((t >> 1) & BN_MASK2) | c; |
| c = (t & 1) ? BN_TBIT : 0; |
| } |
| r->top = j; |
| bn_check_top(r); |
| return (1); |
| } |
| |
| int BN_lshift(BIGNUM *r, const BIGNUM *a, int n) |
| { |
| int i, nw, lb, rb; |
| BN_ULONG *t, *f; |
| BN_ULONG l; |
| |
| bn_check_top(r); |
| bn_check_top(a); |
| |
| r->neg = a->neg; |
| nw = n / BN_BITS2; |
| if (bn_wexpand(r, a->top + nw + 1) == NULL) |
| return (0); |
| lb = n % BN_BITS2; |
| rb = BN_BITS2 - lb; |
| f = a->d; |
| t = r->d; |
| t[a->top + nw] = 0; |
| if (lb == 0) |
| for (i = a->top - 1; i >= 0; i--) |
| t[nw + i] = f[i]; |
| else |
| for (i = a->top - 1; i >= 0; i--) { |
| l = f[i]; |
| t[nw + i + 1] |= (l >> rb) & BN_MASK2; |
| t[nw + i] = (l << lb) & BN_MASK2; |
| } |
| memset(t, 0, nw * sizeof(t[0])); |
| /* |
| * for (i=0; i<nw; i++) t[i]=0; |
| */ |
| r->top = a->top + nw + 1; |
| bn_correct_top(r); |
| bn_check_top(r); |
| return (1); |
| } |
| |
| int BN_rshift(BIGNUM *r, const BIGNUM *a, int n) |
| { |
| int i, j, nw, lb, rb; |
| BN_ULONG *t, *f; |
| BN_ULONG l, tmp; |
| |
| bn_check_top(r); |
| bn_check_top(a); |
| |
| nw = n / BN_BITS2; |
| rb = n % BN_BITS2; |
| lb = BN_BITS2 - rb; |
| if (nw >= a->top || a->top == 0) { |
| BN_zero(r); |
| return (1); |
| } |
| i = (BN_num_bits(a) - n + (BN_BITS2 - 1)) / BN_BITS2; |
| if (r != a) { |
| r->neg = a->neg; |
| if (bn_wexpand(r, i) == NULL) |
| return (0); |
| } else { |
| if (n == 0) |
| return 1; /* or the copying loop will go berserk */ |
| } |
| |
| f = &(a->d[nw]); |
| t = r->d; |
| j = a->top - nw; |
| r->top = i; |
| |
| if (rb == 0) { |
| for (i = j; i != 0; i--) |
| *(t++) = *(f++); |
| } else { |
| l = *(f++); |
| for (i = j - 1; i != 0; i--) { |
| tmp = (l >> rb) & BN_MASK2; |
| l = *(f++); |
| *(t++) = (tmp | (l << lb)) & BN_MASK2; |
| } |
| if ((l = (l >> rb) & BN_MASK2)) |
| *(t) = l; |
| } |
| bn_check_top(r); |
| return (1); |
| } |