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4c74403188
Change-Id: Iae65e95cfa0d92091b8b0a424ae36d88efa76aa9 Reviewed-on: https://review.haiku-os.org/c/buildtools/+/3020 Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
128 lines
3.8 KiB
C
128 lines
3.8 KiB
C
/* mpn_toom_eval_pm2exp -- Evaluate a polynomial in +2^k and -2^k
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Contributed to the GNU project by Niels Möller
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THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE. IT IS ONLY
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SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
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GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.
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Copyright 2009 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of either:
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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or
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* the GNU General Public License as published by the Free Software
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Foundation; either version 2 of the License, or (at your option) any
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later version.
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or both in parallel, as here.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received copies of the GNU General Public License and the
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GNU Lesser General Public License along with the GNU MP Library. If not,
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see https://www.gnu.org/licenses/. */
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#include "gmp-impl.h"
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/* Evaluates a polynomial of degree k > 2, in the points +2^shift and -2^shift. */
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int
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mpn_toom_eval_pm2exp (mp_ptr xp2, mp_ptr xm2, unsigned k,
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mp_srcptr xp, mp_size_t n, mp_size_t hn, unsigned shift,
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mp_ptr tp)
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{
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unsigned i;
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int neg;
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#if HAVE_NATIVE_mpn_addlsh_n
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mp_limb_t cy;
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#endif
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ASSERT (k >= 3);
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ASSERT (shift*k < GMP_NUMB_BITS);
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ASSERT (hn > 0);
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ASSERT (hn <= n);
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/* The degree k is also the number of full-size coefficients, so
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* that last coefficient, of size hn, starts at xp + k*n. */
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#if HAVE_NATIVE_mpn_addlsh_n
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xp2[n] = mpn_addlsh_n (xp2, xp, xp + 2*n, n, 2*shift);
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for (i = 4; i < k; i += 2)
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xp2[n] += mpn_addlsh_n (xp2, xp2, xp + i*n, n, i*shift);
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tp[n] = mpn_lshift (tp, xp+n, n, shift);
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for (i = 3; i < k; i+= 2)
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tp[n] += mpn_addlsh_n (tp, tp, xp+i*n, n, i*shift);
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if (k & 1)
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{
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cy = mpn_addlsh_n (tp, tp, xp+k*n, hn, k*shift);
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MPN_INCR_U (tp + hn, n+1 - hn, cy);
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}
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else
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{
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cy = mpn_addlsh_n (xp2, xp2, xp+k*n, hn, k*shift);
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MPN_INCR_U (xp2 + hn, n+1 - hn, cy);
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}
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#else /* !HAVE_NATIVE_mpn_addlsh_n */
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xp2[n] = mpn_lshift (tp, xp+2*n, n, 2*shift);
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xp2[n] += mpn_add_n (xp2, xp, tp, n);
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for (i = 4; i < k; i += 2)
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{
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xp2[n] += mpn_lshift (tp, xp + i*n, n, i*shift);
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xp2[n] += mpn_add_n (xp2, xp2, tp, n);
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}
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tp[n] = mpn_lshift (tp, xp+n, n, shift);
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for (i = 3; i < k; i+= 2)
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{
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tp[n] += mpn_lshift (xm2, xp + i*n, n, i*shift);
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tp[n] += mpn_add_n (tp, tp, xm2, n);
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}
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xm2[hn] = mpn_lshift (xm2, xp + k*n, hn, k*shift);
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if (k & 1)
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mpn_add (tp, tp, n+1, xm2, hn+1);
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else
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mpn_add (xp2, xp2, n+1, xm2, hn+1);
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#endif /* !HAVE_NATIVE_mpn_addlsh_n */
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neg = (mpn_cmp (xp2, tp, n + 1) < 0) ? ~0 : 0;
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#if HAVE_NATIVE_mpn_add_n_sub_n
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if (neg)
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mpn_add_n_sub_n (xp2, xm2, tp, xp2, n + 1);
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else
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mpn_add_n_sub_n (xp2, xm2, xp2, tp, n + 1);
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#else /* !HAVE_NATIVE_mpn_add_n_sub_n */
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if (neg)
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mpn_sub_n (xm2, tp, xp2, n + 1);
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else
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mpn_sub_n (xm2, xp2, tp, n + 1);
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mpn_add_n (xp2, xp2, tp, n + 1);
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#endif /* !HAVE_NATIVE_mpn_add_n_sub_n */
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/* FIXME: the following asserts are useless if (k+1)*shift >= GMP_LIMB_BITS */
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ASSERT ((k+1)*shift >= GMP_LIMB_BITS ||
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xp2[n] < ((CNST_LIMB(1)<<((k+1)*shift))-1)/((CNST_LIMB(1)<<shift)-1));
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ASSERT ((k+2)*shift >= GMP_LIMB_BITS ||
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xm2[n] < ((CNST_LIMB(1)<<((k+2)*shift))-((k&1)?(CNST_LIMB(1)<<shift):1))/((CNST_LIMB(1)<<(2*shift))-1));
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return neg;
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}
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