|
Packit |
5c3484 |
/* mpn_toom_eval_pm2 -- Evaluate a polynomial in +2 and -2
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
Contributed to the GNU project by Niels Möller and Marco Bodrato
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE. IT IS ONLY
|
|
Packit |
5c3484 |
SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
|
|
Packit |
5c3484 |
GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GNU MP RELEASE.
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
Copyright 2009 Free Software Foundation, Inc.
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
This file is part of the GNU MP Library.
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
The GNU MP Library is free software; you can redistribute it and/or modify
|
|
Packit |
5c3484 |
it under the terms of either:
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
* the GNU Lesser General Public License as published by the Free
|
|
Packit |
5c3484 |
Software Foundation; either version 3 of the License, or (at your
|
|
Packit |
5c3484 |
option) any later version.
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
or
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
* the GNU General Public License as published by the Free Software
|
|
Packit |
5c3484 |
Foundation; either version 2 of the License, or (at your option) any
|
|
Packit |
5c3484 |
later version.
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
or both in parallel, as here.
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
The GNU MP Library is distributed in the hope that it will be useful, but
|
|
Packit |
5c3484 |
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
|
|
Packit |
5c3484 |
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
|
|
Packit |
5c3484 |
for more details.
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
You should have received copies of the GNU General Public License and the
|
|
Packit |
5c3484 |
GNU Lesser General Public License along with the GNU MP Library. If not,
|
|
Packit |
5c3484 |
see https://www.gnu.org/licenses/. */
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
#include "gmp.h"
|
|
Packit |
5c3484 |
#include "gmp-impl.h"
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
/* DO_addlsh2(d,a,b,n,cy) computes cy,{d,n} <- {a,n} + 4*(cy,{b,n}), it
|
|
Packit |
5c3484 |
can be used as DO_addlsh2(d,a,d,n,d[n]), for accumulation on {d,n+1}. */
|
|
Packit |
5c3484 |
#if HAVE_NATIVE_mpn_addlsh2_n
|
|
Packit |
5c3484 |
#define DO_addlsh2(d, a, b, n, cy) \
|
|
Packit |
5c3484 |
do { \
|
|
Packit |
5c3484 |
(cy) <<= 2; \
|
|
Packit |
5c3484 |
(cy) += mpn_addlsh2_n(d, a, b, n); \
|
|
Packit |
5c3484 |
} while (0)
|
|
Packit |
5c3484 |
#else
|
|
Packit |
5c3484 |
#if HAVE_NATIVE_mpn_addlsh_n
|
|
Packit |
5c3484 |
#define DO_addlsh2(d, a, b, n, cy) \
|
|
Packit |
5c3484 |
do { \
|
|
Packit |
5c3484 |
(cy) <<= 2; \
|
|
Packit |
5c3484 |
(cy) += mpn_addlsh_n(d, a, b, n, 2); \
|
|
Packit |
5c3484 |
} while (0)
|
|
Packit |
5c3484 |
#else
|
|
Packit |
5c3484 |
/* The following is not a general substitute for addlsh2.
|
|
Packit |
5c3484 |
It is correct if d == b, but it is not if d == a. */
|
|
Packit |
5c3484 |
#define DO_addlsh2(d, a, b, n, cy) \
|
|
Packit |
5c3484 |
do { \
|
|
Packit |
5c3484 |
(cy) <<= 2; \
|
|
Packit |
5c3484 |
(cy) += mpn_lshift(d, b, n, 2); \
|
|
Packit |
5c3484 |
(cy) += mpn_add_n(d, d, a, n); \
|
|
Packit |
5c3484 |
} while (0)
|
|
Packit |
5c3484 |
#endif
|
|
Packit |
5c3484 |
#endif
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
/* Evaluates a polynomial of degree 2 < k < GMP_NUMB_BITS, in the
|
|
Packit |
5c3484 |
points +2 and -2. */
|
|
Packit |
5c3484 |
int
|
|
Packit |
5c3484 |
mpn_toom_eval_pm2 (mp_ptr xp2, mp_ptr xm2, unsigned k,
|
|
Packit |
5c3484 |
mp_srcptr xp, mp_size_t n, mp_size_t hn, mp_ptr tp)
|
|
Packit |
5c3484 |
{
|
|
Packit |
5c3484 |
int i;
|
|
Packit |
5c3484 |
int neg;
|
|
Packit |
5c3484 |
mp_limb_t cy;
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
ASSERT (k >= 3);
|
|
Packit |
5c3484 |
ASSERT (k < GMP_NUMB_BITS);
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
ASSERT (hn > 0);
|
|
Packit |
5c3484 |
ASSERT (hn <= n);
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
/* The degree k is also the number of full-size coefficients, so
|
|
Packit |
5c3484 |
* that last coefficient, of size hn, starts at xp + k*n. */
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
cy = 0;
|
|
Packit |
5c3484 |
DO_addlsh2 (xp2, xp + (k-2) * n, xp + k * n, hn, cy);
|
|
Packit |
5c3484 |
if (hn != n)
|
|
Packit |
5c3484 |
cy = mpn_add_1 (xp2 + hn, xp + (k-2) * n + hn, n - hn, cy);
|
|
Packit |
5c3484 |
for (i = k - 4; i >= 0; i -= 2)
|
|
Packit |
5c3484 |
DO_addlsh2 (xp2, xp + i * n, xp2, n, cy);
|
|
Packit |
5c3484 |
xp2[n] = cy;
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
k--;
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
cy = 0;
|
|
Packit |
5c3484 |
DO_addlsh2 (tp, xp + (k-2) * n, xp + k * n, n, cy);
|
|
Packit |
5c3484 |
for (i = k - 4; i >= 0; i -= 2)
|
|
Packit |
5c3484 |
DO_addlsh2 (tp, xp + i * n, tp, n, cy);
|
|
Packit |
5c3484 |
tp[n] = cy;
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
if (k & 1)
|
|
Packit |
5c3484 |
ASSERT_NOCARRY(mpn_lshift (tp , tp , n + 1, 1));
|
|
Packit |
5c3484 |
else
|
|
Packit |
5c3484 |
ASSERT_NOCARRY(mpn_lshift (xp2, xp2, n + 1, 1));
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
neg = (mpn_cmp (xp2, tp, n + 1) < 0) ? ~0 : 0;
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
#if HAVE_NATIVE_mpn_add_n_sub_n
|
|
Packit |
5c3484 |
if (neg)
|
|
Packit |
5c3484 |
mpn_add_n_sub_n (xp2, xm2, tp, xp2, n + 1);
|
|
Packit |
5c3484 |
else
|
|
Packit |
5c3484 |
mpn_add_n_sub_n (xp2, xm2, xp2, tp, n + 1);
|
|
Packit |
5c3484 |
#else /* !HAVE_NATIVE_mpn_add_n_sub_n */
|
|
Packit |
5c3484 |
if (neg)
|
|
Packit |
5c3484 |
mpn_sub_n (xm2, tp, xp2, n + 1);
|
|
Packit |
5c3484 |
else
|
|
Packit |
5c3484 |
mpn_sub_n (xm2, xp2, tp, n + 1);
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
mpn_add_n (xp2, xp2, tp, n + 1);
|
|
Packit |
5c3484 |
#endif /* !HAVE_NATIVE_mpn_add_n_sub_n */
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
ASSERT (xp2[n] < (1<<(k+2))-1);
|
|
Packit |
5c3484 |
ASSERT (xm2[n] < ((1<<(k+3))-1 - (1^k&1))/3);
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
neg ^= ((k & 1) - 1);
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
return neg;
|
|
Packit |
5c3484 |
}
|
|
Packit |
5c3484 |
|
|
Packit |
5c3484 |
#undef DO_addlsh2
|