1*86d7f5d3SJohn Marino /* Helper function for high degree Toom-Cook algorithms.
2*86d7f5d3SJohn Marino
3*86d7f5d3SJohn Marino Contributed to the GNU project by Marco Bodrato.
4*86d7f5d3SJohn Marino
5*86d7f5d3SJohn Marino THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE. IT IS ONLY
6*86d7f5d3SJohn Marino SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
7*86d7f5d3SJohn Marino GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.
8*86d7f5d3SJohn Marino
9*86d7f5d3SJohn Marino Copyright 2009, 2010 Free Software Foundation, Inc.
10*86d7f5d3SJohn Marino
11*86d7f5d3SJohn Marino This file is part of the GNU MP Library.
12*86d7f5d3SJohn Marino
13*86d7f5d3SJohn Marino The GNU MP Library is free software; you can redistribute it and/or modify
14*86d7f5d3SJohn Marino it under the terms of the GNU Lesser General Public License as published by
15*86d7f5d3SJohn Marino the Free Software Foundation; either version 3 of the License, or (at your
16*86d7f5d3SJohn Marino option) any later version.
17*86d7f5d3SJohn Marino
18*86d7f5d3SJohn Marino The GNU MP Library is distributed in the hope that it will be useful, but
19*86d7f5d3SJohn Marino WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
20*86d7f5d3SJohn Marino or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
21*86d7f5d3SJohn Marino License for more details.
22*86d7f5d3SJohn Marino
23*86d7f5d3SJohn Marino You should have received a copy of the GNU Lesser General Public License
24*86d7f5d3SJohn Marino along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
25*86d7f5d3SJohn Marino
26*86d7f5d3SJohn Marino
27*86d7f5d3SJohn Marino #include "gmp.h"
28*86d7f5d3SJohn Marino #include "gmp-impl.h"
29*86d7f5d3SJohn Marino
30*86d7f5d3SJohn Marino /* Gets {pp,n} and (sign?-1:1)*{np,n}. Computes at once:
31*86d7f5d3SJohn Marino {pp,n} <- ({pp,n}+{np,n})/2^{ps+1}
32*86d7f5d3SJohn Marino {pn,n} <- ({pp,n}-{np,n})/2^{ns+1}
33*86d7f5d3SJohn Marino Finally recompose them obtaining:
34*86d7f5d3SJohn Marino {pp,n+off} <- {pp,n}+{np,n}*2^{off*GMP_NUMB_BITS}
35*86d7f5d3SJohn Marino */
36*86d7f5d3SJohn Marino void
mpn_toom_couple_handling(mp_ptr pp,mp_size_t n,mp_ptr np,int nsign,mp_size_t off,int ps,int ns)37*86d7f5d3SJohn Marino mpn_toom_couple_handling (mp_ptr pp, mp_size_t n, mp_ptr np,
38*86d7f5d3SJohn Marino int nsign, mp_size_t off, int ps, int ns)
39*86d7f5d3SJohn Marino {
40*86d7f5d3SJohn Marino if (nsign) {
41*86d7f5d3SJohn Marino #ifdef HAVE_NATIVE_mpn_rsh1sub_n
42*86d7f5d3SJohn Marino mpn_rsh1sub_n (np, pp, np, n);
43*86d7f5d3SJohn Marino #else
44*86d7f5d3SJohn Marino mpn_sub_n (np, pp, np, n);
45*86d7f5d3SJohn Marino mpn_rshift (np, np, n, 1);
46*86d7f5d3SJohn Marino #endif
47*86d7f5d3SJohn Marino } else {
48*86d7f5d3SJohn Marino #ifdef HAVE_NATIVE_mpn_rsh1add_n
49*86d7f5d3SJohn Marino mpn_rsh1add_n (np, pp, np, n);
50*86d7f5d3SJohn Marino #else
51*86d7f5d3SJohn Marino mpn_add_n (np, pp, np, n);
52*86d7f5d3SJohn Marino mpn_rshift (np, np, n, 1);
53*86d7f5d3SJohn Marino #endif
54*86d7f5d3SJohn Marino }
55*86d7f5d3SJohn Marino
56*86d7f5d3SJohn Marino #ifdef HAVE_NATIVE_mpn_rsh1sub_n
57*86d7f5d3SJohn Marino if (ps == 1)
58*86d7f5d3SJohn Marino mpn_rsh1sub_n (pp, pp, np, n);
59*86d7f5d3SJohn Marino else
60*86d7f5d3SJohn Marino #endif
61*86d7f5d3SJohn Marino {
62*86d7f5d3SJohn Marino mpn_sub_n (pp, pp, np, n);
63*86d7f5d3SJohn Marino if (ps > 0)
64*86d7f5d3SJohn Marino mpn_rshift (pp, pp, n, ps);
65*86d7f5d3SJohn Marino }
66*86d7f5d3SJohn Marino if (ns > 0)
67*86d7f5d3SJohn Marino mpn_rshift (np, np, n, ns);
68*86d7f5d3SJohn Marino pp[n] = mpn_add_n (pp+off, pp+off, np, n-off);
69*86d7f5d3SJohn Marino ASSERT_NOCARRY (mpn_add_1(pp+n, np+n-off, off, pp[n]) );
70*86d7f5d3SJohn Marino }
71