1/* mpn_mul_1 -- Multiply a limb vector with a single limb and
2   store the product in a second limb vector.
3
4Copyright (C) 1991, 1992, 1993, 1994, 1996 Free Software Foundation, Inc.
5
6This file is part of the GNU MP Library.
7
8The GNU MP Library is free software; you can redistribute it and/or modify
9it under the terms of the GNU Library General Public License as published by
10the Free Software Foundation; either version 2 of the License, or (at your
11option) any later version.
12
13The GNU MP Library is distributed in the hope that it will be useful, but
14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
16License for more details.
17
18You should have received a copy of the GNU Library General Public License
19along with the GNU MP Library; see the file COPYING.LIB.  If not, write to
20the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
21MA 02111-1307, USA. */
22
23#include "gmp.h"
24#include "gmp-impl.h"
25#include "longlong.h"
26
27mp_limb_t
28mpn_mul_1 (res_ptr, s1_ptr, s1_size, s2_limb)
29     register mp_ptr res_ptr;
30     register mp_srcptr s1_ptr;
31     mp_size_t s1_size;
32     register mp_limb_t s2_limb;
33{
34  register mp_limb_t cy_limb;
35  register mp_size_t j;
36  register mp_limb_t prod_high, prod_low;
37
38  /* The loop counter and index J goes from -S1_SIZE to -1.  This way
39     the loop becomes faster.  */
40  j = -s1_size;
41
42  /* Offset the base pointers to compensate for the negative indices.  */
43  s1_ptr -= j;
44  res_ptr -= j;
45
46  cy_limb = 0;
47  do
48    {
49      umul_ppmm (prod_high, prod_low, s1_ptr[j], s2_limb);
50
51      prod_low += cy_limb;
52      cy_limb = (prod_low < cy_limb) + prod_high;
53
54      res_ptr[j] = prod_low;
55    }
56  while (++j != 0);
57
58  return cy_limb;
59}
60