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 Lesser General Public License as published by
10the Free Software Foundation; either version 2.1 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 Lesser General Public
16License for more details.
17
18You should have received a copy of the GNU Lesser 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 <config.h>
24#include "gmp-impl.h"
25
26mp_limb_t
27mpn_mul_1 (res_ptr, s1_ptr, s1_size, s2_limb)
28 register mp_ptr res_ptr;
29 register mp_srcptr s1_ptr;
30 mp_size_t s1_size;
31 register mp_limb_t s2_limb;
32{
33 register mp_limb_t cy_limb;
34 register mp_size_t j;
35 register mp_limb_t prod_high, prod_low;
36
37 /* The loop counter and index J goes from -S1_SIZE to -1. This way
38 the loop becomes faster. */
39 j = -s1_size;
40
41 /* Offset the base pointers to compensate for the negative indices. */
42 s1_ptr -= j;
43 res_ptr -= j;
44
45 cy_limb = 0;
46 do
47 {
48 umul_ppmm (prod_high, prod_low, s1_ptr[j], s2_limb);
49
50 prod_low += cy_limb;
51 cy_limb = (prod_low < cy_limb) + prod_high;
52
53 res_ptr[j] = prod_low;
54 }
55 while (++j != 0);
56
57 return cy_limb;
58}
59