1/* mpn_mullo_basecase -- Internal routine to multiply two natural
2   numbers of length n and return the low part.
3
4   THIS IS AN INTERNAL FUNCTION WITH A MUTABLE INTERFACE.  IT IS ONLY
5   SAFE TO REACH THIS FUNCTION THROUGH DOCUMENTED INTERFACES.
6
7
8Copyright (C) 2000, 2002, 2004, 2015 Free Software Foundation, Inc.
9
10This file is part of the GNU MP Library.
11
12The GNU MP Library is free software; you can redistribute it and/or modify
13it under the terms of either:
14
15  * the GNU Lesser General Public License as published by the Free
16    Software Foundation; either version 3 of the License, or (at your
17    option) any later version.
18
19or
20
21  * the GNU General Public License as published by the Free Software
22    Foundation; either version 2 of the License, or (at your option) any
23    later version.
24
25or both in parallel, as here.
26
27The GNU MP Library is distributed in the hope that it will be useful, but
28WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
29or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
30for more details.
31
32You should have received copies of the GNU General Public License and the
33GNU Lesser General Public License along with the GNU MP Library.  If not,
34see https://www.gnu.org/licenses/.  */
35
36#include "gmp-impl.h"
37
38/* FIXME: Should optionally use mpn_mul_2/mpn_addmul_2.  */
39
40#ifndef MULLO_VARIANT
41#define MULLO_VARIANT 2
42#endif
43
44
45#if MULLO_VARIANT == 1
46void
47mpn_mullo_basecase (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n)
48{
49  mp_size_t i;
50
51  mpn_mul_1 (rp, up, n, vp[0]);
52
53  for (i = n - 1; i > 0; i--)
54    {
55      vp++;
56      rp++;
57      mpn_addmul_1 (rp, up, i, vp[0]);
58    }
59}
60#endif
61
62
63#if MULLO_VARIANT == 2
64void
65mpn_mullo_basecase (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n)
66{
67  mp_limb_t h;
68
69  h = up[0] * vp[n - 1];
70
71  if (n != 1)
72    {
73      mp_size_t i;
74      mp_limb_t v0;
75
76      v0 = *vp++;
77      h += up[n - 1] * v0 + mpn_mul_1 (rp, up, n - 1, v0);
78      rp++;
79
80      for (i = n - 2; i > 0; i--)
81	{
82	  v0 = *vp++;
83	  h += up[i] * v0 + mpn_addmul_1 (rp, up, i, v0);
84	  rp++;
85	}
86    }
87
88  rp[0] = h;
89}
90#endif
91