1/* mpih-mul2.c  -  MPI helper functions
2 * Copyright (C) 1994, 1996, 1997, 1998, 2001,
3 *               2002  Free Software Foundation, Inc.
4 *
5 * This file is part of Libgcrypt.
6 *
7 * Libgcrypt is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU Lesser General Public License as
9 * published by the Free Software Foundation; either version 2.1 of
10 * the License, or (at your option) any later version.
11 *
12 * Libgcrypt is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15 * GNU Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this program; if not, write to the Free Software
19 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
20 *
21 * Note: This code is heavily based on the GNU MP Library.
22 *	 Actually it's the same code with only minor changes in the
23 *	 way the data is stored; this is to support the abstraction
24 *	 of an optional secure memory allocation which may be used
25 *	 to avoid revealing of sensitive data due to paging etc.
26 */
27
28#include <config.h>
29#include <stdio.h>
30#include <stdlib.h>
31#include "mpi-internal.h"
32#include "longlong.h"
33
34
35mpi_limb_t
36_gcry_mpih_addmul_1( mpi_ptr_t res_ptr, mpi_ptr_t s1_ptr,
37		  mpi_size_t s1_size, mpi_limb_t s2_limb)
38{
39  mpi_limb_t cy_limb;
40  mpi_size_t j;
41  mpi_limb_t prod_high, prod_low;
42  mpi_limb_t x;
43
44  /* The loop counter and index J goes from -SIZE to -1.  This way
45   * the loop becomes faster.  */
46  j = -s1_size;
47  res_ptr -= j;
48  s1_ptr -= j;
49
50  cy_limb = 0;
51  do
52    {
53      umul_ppmm( prod_high, prod_low, s1_ptr[j], s2_limb );
54
55      prod_low += cy_limb;
56      cy_limb = (prod_low < cy_limb?1:0) + prod_high;
57
58      x = res_ptr[j];
59      prod_low = x + prod_low;
60      cy_limb += prod_low < x?1:0;
61      res_ptr[j] = prod_low;
62    }
63  while ( ++j );
64
65  return cy_limb;
66}
67
68
69