77 lines
2.1 KiB
C
77 lines
2.1 KiB
C
|
/* mpn_dc_div_q -- divide-and-conquer division, returning exact quotient
|
||
|
|
only.
|
||
|
|
|
||
|
|
Contributed to the GNU project by Torbjorn Granlund and Marco Bodrato.
|
||
|
|
|
||
|
|
THE FUNCTION IN THIS FILE IS INTERNAL WITH A MUTABLE INTERFACE. IT IS ONLY
|
||
|
|
SAFE TO REACH IT THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
|
||
|
|
GUARANTEED THAT IT WILL CHANGE OR DISAPPEAR IN A FUTURE GMP RELEASE.
|
||
|
|
|
||
|
|
Copyright 2006, 2007, 2009, 2010 Free Software Foundation, Inc.
|
||
|
|
|
||
|
|
This file is part of the GNU MP Library.
|
||
|
|
|
||
|
|
The GNU MP 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 3 of the License, or (at your
|
||
|
|
option) any later version.
|
||
|
|
|
||
|
|
The GNU MP 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 GNU MP Library. If not, see http://www.gnu.org/licenses/. */
|
||
|
|
|
||
|
|
#include "mpir.h"
|
||
|
|
#include "gmp-impl.h"
|
||
|
|
|
||
|
|
|
||
|
|
mp_limb_t
|
||
|
|
mpn_dc_div_q (mp_ptr qp, mp_ptr np, mp_size_t nn,
|
||
|
|
mp_srcptr dp, mp_size_t dn, mp_srcptr dinv)
|
||
|
|
{
|
||
|
|
mp_ptr tp, wp;
|
||
|
|
mp_limb_t qh;
|
||
|
|
mp_size_t qn;
|
||
|
|
TMP_DECL;
|
||
|
|
|
||
|
|
TMP_MARK;
|
||
|
|
|
||
|
|
ASSERT (dn >= 6);
|
||
|
|
ASSERT (nn - dn >= 3);
|
||
|
|
ASSERT (dp[dn-1] & GMP_NUMB_HIGHBIT);
|
||
|
|
|
||
|
|
tp = TMP_SALLOC_LIMBS (nn + 1);
|
||
|
|
MPN_COPY (tp + 1, np, nn);
|
||
|
|
tp[0] = 0;
|
||
|
|
|
||
|
|
qn = nn - dn;
|
||
|
|
wp = TMP_SALLOC_LIMBS (qn + 1);
|
||
|
|
|
||
|
|
qh = mpn_dc_divappr_q (wp, tp, nn + 1, dp, dn, dinv);
|
||
|
|
|
||
|
|
if (wp[0] == 0)
|
||
|
|
{
|
||
|
|
mp_limb_t cy;
|
||
|
|
|
||
|
|
if (qn > dn)
|
||
|
|
mpn_mul (tp, wp + 1, qn, dp, dn);
|
||
|
|
else
|
||
|
|
mpn_mul (tp, dp, dn, wp + 1, qn);
|
||
|
|
|
||
|
|
cy = (qh != 0) ? mpn_add_n (tp + qn, tp + qn, dp, dn) : 0;
|
||
|
|
|
||
|
|
if (cy || mpn_cmp (tp, np, nn) > 0) /* At most is wrong by one, no cycle. */
|
||
|
|
qh -= mpn_sub_1 (qp, wp + 1, qn, 1);
|
||
|
|
else /* Same as below */
|
||
|
|
MPN_COPY (qp, wp + 1, qn);
|
||
|
|
}
|
||
|
|
else
|
||
|
|
MPN_COPY (qp, wp + 1, qn);
|
||
|
|
|
||
|
|
TMP_FREE;
|
||
|
|
return qh;
|
||
|
|
}
|