mpir/mpn/generic/mod_1_3.c

81 lines
2.2 KiB
C

/*
dnl Copyright 2009 Jason Moxham
dnl This file is part of the MPIR Library.
dnl The MPIR Library is free software; you can redistribute it and/or modify
dnl it under the terms of the GNU Lesser General Public License as published
dnl by the Free Software Foundation; either version 2.1 of the License, or (at
dnl your option) any later version.
dnl The MPIR Library is distributed in the hope that it will be useful, but
dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
dnl License for more details.
dnl You should have received a copy of the GNU Lesser General Public License
dnl along with the MPIR Library; see the file COPYING.LIB. If not, write
dnl to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
dnl Boston, MA 02110-1301, USA.
*/
#include "mpir.h"
#include "gmp-impl.h"
#include "longlong.h"
/* in each round we remove one limb from the body, i.e. k = 1 */
void mpn_mod_1_3(mp_ptr rem, mp_srcptr xp, mp_size_t xn, mp_srcptr db)
{
mp_limb_t h, l, sh, sl, th, tl;
mp_size_t j, jj;
ASSERT(xn >= 5);
ASSERT_MPN(xp, xn);
ASSERT_LIMB(db[0]);
ASSERT_LIMB(db[1]);
ASSERT_LIMB(db[2]);
ASSERT_LIMB(db[3]);
tl = xp[xn - 2];
th = xp[xn - 1];
for (j = xn - 5; j >= 0; j -= 3)
{
umul_ppmm(sh, sl, xp[j + 1], db[0]);
add_ssaaaa(sh, sl, sh, sl, 0, xp[j]);
umul_ppmm(h, l, xp[j + 2], db[1]);
add_ssaaaa(sh, sl, sh, sl, h, l);
umul_ppmm(h, l, tl, db[2]);
add_ssaaaa(sh, sl, sh, sl, h, l);
umul_ppmm(th, tl, th, db[3]);
add_ssaaaa(th, tl, th, tl, sh, sl);
}
if (j > -3) /* we have at least three limbs to do, i.e. xp[0], ..., tl, th */
{
sh = 0;
sl = xp[0];
jj = 1;
if (j == -1)
{
umul_ppmm(sh, sl, xp[1], db[0]);
add_ssaaaa(sh, sl, sh, sl, 0, xp[0]);
jj = 2;
}
umul_ppmm(h, l, tl, db[jj - 1]);
add_ssaaaa(sh, sl, sh, sl, h, l);
umul_ppmm(th, tl, th, db[jj]);
add_ssaaaa(th, tl, th, tl, sh, sl);
}
umul_ppmm(h, l, th, db[0]);
add_ssaaaa(h, l, h, l, 0, tl);
rem[0] = l;
rem[1] = h;
}