/* mpn_toom_eval_dgr3_pm2 -- Evaluate a degree 3 polynomial in +2 and -2 Contributed to the GNU project by Niels Möller THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE. IT IS ONLY SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE. Copyright 2009 Free Software Foundation, Inc. This file is part of the GNU MP Library. The GNU MP Library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. The GNU MP Library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */ #include "mpir.h" #include "gmp-impl.h" /* Needs n+1 limbs of temporary storage. */ int mpn_toom_eval_dgr3_pm2 (mp_ptr xp2, mp_ptr xm2, mp_srcptr xp, mp_size_t n, mp_size_t x3n, mp_ptr tp) { mp_limb_t cy; int neg; ASSERT (x3n > 0); ASSERT (x3n <= n); /* (x0 + 4 * x2) +/- (2 x1 + 8 x_3) */ #if HAVE_NATIVE_mpn_addlsh_n || HAVE_NATIVE_mpn_addlsh2_n #if HAVE_NATIVE_mpn_addlsh2_n xp2[n] = mpn_addlsh2_n (xp2, xp, xp + 2*n, n); cy = mpn_addlsh2_n (tp, xp + n, xp + 3*n, x3n); #else /* HAVE_NATIVE_mpn_addlsh_n */ xp2[n] = mpn_addlsh_n (xp2, xp, xp + 2*n, n, 2); cy = mpn_addlsh_n (tp, xp + n, xp + 3*n, x3n, 2); #endif if (x3n < n) cy = mpn_add_1 (tp + x3n, xp + n + x3n, n - x3n, cy); tp[n] = cy; #else cy = mpn_lshift (tp, xp + 2*n, n, 2); xp2[n] = cy + mpn_add_n (xp2, tp, xp, n); tp[x3n] = mpn_lshift (tp, xp + 3*n, x3n, 2); if (x3n < n) tp[n] = mpn_add (tp, xp + n, n, tp, x3n + 1); else tp[n] += mpn_add_n (tp, xp + n, tp, n); #endif mpn_lshift (tp, tp, n+1, 1); neg = (mpn_cmp (xp2, tp, n + 1) < 0) ? ~0 : 0; #if HAVE_NATIVE_mpn_sumdiff_n if (neg) mpn_sumdiff_n (xp2, xm2, tp, xp2, n + 1); else mpn_sumdiff_n (xp2, xm2, xp2, tp, n + 1); #else if (neg) mpn_sub_n (xm2, tp, xp2, n + 1); else mpn_sub_n (xm2, xp2, tp, n + 1); mpn_add_n (xp2, xp2, tp, n + 1); #endif ASSERT (xp2[n] < 15); ASSERT (xm2[n] < 10); return neg; }