toom_eval_dgr3_pm2.c
上传用户:qaz666999
上传日期:2022-08-06
资源大小:2570k
文件大小:2k
- /* mpn_toom_eval_dgr3_pm2 -- Evaluate a degree 3 polynomial in +2 and -2
- Contributed to the GNU project by Niels M鰈ler
- 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 "gmp.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_add_n_sub_n
- if (neg)
- mpn_add_n_sub_n (xp2, xm2, tp, xp2, n + 1);
- else
- mpn_add_n_sub_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;
- }