mpir/mpn/generic/divrem_hensel_r_1.c

69 lines
1.5 KiB
C

/*
Copyright 2009 Jason Moxham
This file is part of the MPIR Library.
The MPIR 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 2.1 of the License, or (at
your option) any later version.
The MPIR 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 MPIR Library; see the file COPYING.LIB. If not, write
to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#include "mpir.h"
#include "gmp-impl.h"
#include "longlong.h"
/*
(xp, n) = (qp, n)*d - ret*B^n and 0 <= ret < d
same as qr version but with q not stored
*/
mp_limb_t mpn_divrem_hensel_r_1(mp_srcptr xp, mp_size_t n, mp_limb_t d)
{
mp_size_t j;
mp_limb_t c, h, q, dummy, h1, t, m;
ASSERT(n > 0);
ASSERT_MPN(xp, n);
ASSERT(d%2 == 1);
modlimb_invert(m, d);
c = 0;
h = 0;
t = 0;
for (j = 0; j <= n - 1; j++)
{
h1 = xp[j];
t = h + c;
if (t > h1)
{
h1 = h1 - t;
c = 1;
}
else
{
h1 = h1 - t;
c = 0;
}
q = h1*m;
umul_ppmm(h, dummy, q, d);
ASSERT(dummy == h1);
}
return h + c;
}