mpir/mpn/generic/divrem_hensel_r_1.c

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/*
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"
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;} // so (xp,n) = (qp,n)*d -ret*B^n and 0 <= ret < d
// same as qr version but with q not stored