source: grub-pc/trunk/fuentes/grub-core/lib/libgcrypt-grub/mpi/generic/mpih-lshift.c @ 22

Last change on this file since 22 was 22, checked in by mabarracus, 4 years ago

updated version and apply net.ifnames=0 into debian/rules

File size: 2.1 KB
Line 
1/* mpi-lshift.c  - MPI helper functions
2 * Copyright (C) 1994, 1996, 1998, 2001, 2002 Free Software Foundation, Inc.
3 *
4 * This file is part of Libgcrypt.
5 *
6 * Libgcrypt is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser General Public License as
8 * published by the Free Software Foundation; either version 2.1 of
9 * the License, or (at your option) any later version.
10 *
11 * Libgcrypt is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14 * GNU Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
19 *
20 * Note: This code is heavily based on the GNU MP Library.
21 *       Actually it's the same code with only minor changes in the
22 *       way the data is stored; this is to support the abstraction
23 *       of an optional secure memory allocation which may be used
24 *       to avoid revealing of sensitive data due to paging etc.
25 */
26
27#include <config.h>
28#include <stdio.h>
29#include <stdlib.h>
30#include "mpi-internal.h"
31
32/* Shift U (pointed to by UP and USIZE digits long) CNT bits to the left
33 * and store the USIZE least significant digits of the result at WP.
34 * Return the bits shifted out from the most significant digit.
35 *
36 * Argument constraints:
37 * 1. 0 < CNT < BITS_PER_MP_LIMB
38 * 2. If the result is to be written over the input, WP must be >= UP.
39 */
40
41mpi_limb_t
42_gcry_mpih_lshift( mpi_ptr_t wp, mpi_ptr_t up, mpi_size_t usize,
43                                            unsigned int cnt)
44{
45  mpi_limb_t high_limb, low_limb;
46  unsigned sh_1, sh_2;
47  mpi_size_t i;
48  mpi_limb_t retval;
49
50  sh_1 = cnt;
51  wp += 1;
52  sh_2 = BITS_PER_MPI_LIMB - sh_1;
53  i = usize - 1;
54  low_limb = up[i];
55  retval = low_limb >> sh_2;
56  high_limb = low_limb;
57  while ( --i >= 0 ) 
58    {
59      low_limb = up[i];
60      wp[i] = (high_limb << sh_1) | (low_limb >> sh_2);
61      high_limb = low_limb;
62    }
63  wp[i] = high_limb << sh_1;
64
65  return retval;
66}
67
68
Note: See TracBrowser for help on using the repository browser.