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Switched ove to GMP dc_divappr_q_n code.

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(no author) 2010-02-24 01:02:55 +00:00
parent 4e012be2c4
commit 80d9c85d77
1 changed files with 77 additions and 0 deletions
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77
mpn/generic/dc_divappr_q_n.c
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@ -1,3 +1,78 @@
/* mpn_dc_divappr_q_n -- divide-and-conquer division, returning approximate
quotient. The quotient returned is either correct, or one too large.
Contributed to the GNU project by Torbjorn Granlund.
THE FUNCTIONS IN THIS FILE ARE INTERNAL WITH MUTABLE INTERFACES. IT IS ONLY
SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS ALMOST
GUARANTEED THAT THEY 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"
#include "longlong.h"
mp_limb_t
mpn_dcp_divappr_q_n (mp_ptr qp, mp_ptr np, mp_srcptr dp, mp_size_t n,
mp_limb_t dinv, mp_ptr tp)
{
mp_size_t lo, hi;
mp_limb_t cy, qh, ql;
lo = n >> 1; /* floor(n/2) */
hi = n - lo; /* ceil(n/2) */
if (BELOW_THRESHOLD (hi, DC_DIV_QR_THRESHOLD))
qh = mpn_sb_div_qr (qp + lo, np + 2 * lo, 2 * hi, dp + lo, hi, dinv);
else
qh = mpn_dc_div_qr_n (qp + lo, np + 2 * lo, dp + lo, hi, dinv, tp);
mpn_mul (tp, qp + lo, hi, dp, lo);
cy = mpn_sub_n (np + lo, np + lo, tp, n);
if (qh != 0)
cy += mpn_sub_n (np + n, np + n, dp, lo);
while (cy != 0)
{
qh -= mpn_sub_1 (qp + lo, qp + lo, hi, 1);
cy -= mpn_add_n (np + lo, np + lo, dp, n);
}
if (BELOW_THRESHOLD (lo, DC_DIVAPPR_Q_N_THRESHOLD))
ql = mpn_sb_divappr_q (qp, np + hi, 2 * lo, dp + hi, lo, dinv);
else
ql = mpn_dc_divappr_q_n (qp, np + hi, dp + hi, lo, dinv, tp);
if (UNLIKELY (ql != 0))
{
mp_size_t i;
for (i = 0; i < lo; i++)
qp[i] = GMP_NUMB_MASK;
}
return qh;
}
#if 0 /* This code seems to be unconditionally slower than that above */
/* dc_divappr_q - middle-product-based divide and conquer approximate quotient
Copyright (C) 2009, David Harvey
@ -170,3 +245,5 @@ mpn_dc_divappr_q_n (mp_ptr qp, mp_ptr np, mp_srcptr dp, mp_size_t n,
return ret;
}
#endif