1 /* mpn_toom_eval_dgr3_pm2 -- Evaluate a degree 3 polynomial in +2 and -2
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 /* Needs n+1 limbs of temporary storage. */
32 mpn_toom_eval_dgr3_pm2 (mp_ptr xp2, mp_ptr xm2,
33 mp_srcptr xp, mp_size_t n, mp_size_t x3n, mp_ptr tp)
41 /* (x0 + 4 * x2) +/- (2 x1 + 8 x_3) */
42 #if HAVE_NATIVE_mpn_addlsh_n || HAVE_NATIVE_mpn_addlsh2_n
43 #if HAVE_NATIVE_mpn_addlsh2_n
44 xp2[n] = mpn_addlsh2_n (xp2, xp, xp + 2*n, n);
46 cy = mpn_addlsh2_n (tp, xp + n, xp + 3*n, x3n);
47 #else /* HAVE_NATIVE_mpn_addlsh_n */
48 xp2[n] = mpn_addlsh_n (xp2, xp, xp + 2*n, n, 2);
50 cy = mpn_addlsh_n (tp, xp + n, xp + 3*n, x3n, 2);
53 cy = mpn_add_1 (tp + x3n, xp + n + x3n, n - x3n, cy);
56 cy = mpn_lshift (tp, xp + 2*n, n, 2);
57 xp2[n] = cy + mpn_add_n (xp2, tp, xp, n);
59 tp[x3n] = mpn_lshift (tp, xp + 3*n, x3n, 2);
61 tp[n] = mpn_add (tp, xp + n, n, tp, x3n + 1);
63 tp[n] += mpn_add_n (tp, xp + n, tp, n);
65 mpn_lshift (tp, tp, n+1, 1);
67 neg = (mpn_cmp (xp2, tp, n + 1) < 0) ? ~0 : 0;
69 #if HAVE_NATIVE_mpn_add_n_sub_n
71 mpn_add_n_sub_n (xp2, xm2, tp, xp2, n + 1);
73 mpn_add_n_sub_n (xp2, xm2, xp2, tp, n + 1);
76 mpn_sub_n (xm2, tp, xp2, n + 1);
78 mpn_sub_n (xm2, xp2, tp, n + 1);
80 mpn_add_n (xp2, xp2, tp, n + 1);