53 lines
1.7 KiB
C
53 lines
1.7 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"
|
|
|
|
// using a two limb inverse of a one limb divisor
|
|
mp_limb_t mpn_divrem_hensel_qr_1_2(mp_ptr qp, mp_srcptr xp, mp_size_t n, mp_limb_t d)
|
|
{mp_size_t j;mp_limb_t c,h,q,dummy,h1,t,ml,mh,xl,xh,ql,qh;
|
|
|
|
ASSERT(n>=2);ASSERT_MPN(xp,n);ASSERT(MPN_SAME_OR_SEPARATE_P(qp,xp,n));
|
|
ASSERT(d%2==1);
|
|
modlimb_invert(ml,d);
|
|
umul_ppmm(h,dummy,d,ml);ASSERT(dummy==1);
|
|
h=-h;mh=ml*h;// (mh,ml) is our two limb inverse
|
|
c=0;h=0;
|
|
for(j=0;j+1<=n-1;j+=2)
|
|
{xl=xp[j];xh=xp[j+1];
|
|
t=h+c;if(xh==0 && t>xl){c=1;}else{c=0;}
|
|
sub_ddmmss(xh,xl,xh,xl,0,t);
|
|
umul_ppmm(qh,ql,xl,ml);
|
|
qh=qh+xh*ml+xl*mh;
|
|
qp[j]=ql;qp[j+1]=qh;
|
|
umul_ppmm(h,h1,qh,d);
|
|
if(h1>xh)h++;}
|
|
if(j<=n-1)
|
|
{h1=xp[j];
|
|
t=h+c;if(t>h1){h1=h1-t;c=1;}else{h1=h1-t;c=0;}
|
|
q=h1*ml;
|
|
qp[j]=q;
|
|
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
|