1 /* mpn_toom_eval_pm1 -- Evaluate a polynomial in +1 and -1
3 Contributed to the GNU project by Niels Möller
5 THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE. IT IS ONLY
6 SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
7 GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.
9 Copyright 2009 Free Software Foundation, Inc.
11 This file is part of the GNU MP Library.
13 The GNU MP Library is free software; you can redistribute it and/or modify
14 it under the terms of the GNU Lesser General Public License as published by
15 the Free Software Foundation; either version 3 of the License, or (at your
16 option) any later version.
18 The GNU MP Library is distributed in the hope that it will be useful, but
19 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
20 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
21 License for more details.
23 You should have received a copy of the GNU Lesser General Public License
24 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
30 /* Evaluates a polynomial of degree k > 3, in the points +1 and -1. */
32 mpn_toom_eval_pm1 (mp_ptr xp1, mp_ptr xm1, unsigned k,
33 mp_srcptr xp, mp_size_t n, mp_size_t hn, mp_ptr tp)
43 /* The degree k is also the number of full-size coefficients, so
44 * that last coefficient, of size hn, starts at xp + k*n. */
46 xp1[n] = mpn_add_n (xp1, xp, xp + 2*n, n);
47 for (i = 4; i < k; i += 2)
48 ASSERT_NOCARRY (mpn_add (xp1, xp1, n+1, xp+i*n, n));
50 tp[n] = mpn_add_n (tp, xp + n, xp + 3*n, n);
51 for (i = 5; i < k; i += 2)
52 ASSERT_NOCARRY (mpn_add (tp, tp, n+1, xp+i*n, n));
55 ASSERT_NOCARRY (mpn_add (tp, tp, n+1, xp+k*n, hn));
57 ASSERT_NOCARRY (mpn_add (xp1, xp1, n+1, xp+k*n, hn));
59 neg = (mpn_cmp (xp1, tp, n + 1) < 0) ? ~0 : 0;
61 #if HAVE_NATIVE_mpn_add_n_sub_n
63 mpn_add_n_sub_n (xp1, xm1, tp, xp1, n + 1);
65 mpn_add_n_sub_n (xp1, xm1, xp1, tp, n + 1);
68 mpn_sub_n (xm1, tp, xp1, n + 1);
70 mpn_sub_n (xm1, xp1, tp, n + 1);
72 mpn_add_n (xp1, xp1, tp, n + 1);
76 ASSERT (xm1[n] <= k/2 + 1);