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4c74403188
Change-Id: Iae65e95cfa0d92091b8b0a424ae36d88efa76aa9 Reviewed-on: https://review.haiku-os.org/c/buildtools/+/3020 Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>
83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
/* mpn_sbpi1_bdiv_qr -- schoolbook Hensel division with precomputed inverse,
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returning quotient and remainder.
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Contributed to the GNU project by Niels Möller and Torbjörn Granlund.
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THE FUNCTIONS IN THIS FILE ARE INTERNAL FUNCTIONS WITH MUTABLE INTERFACES.
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IT IS ONLY SAFE TO REACH THEM THROUGH DOCUMENTED INTERFACES. IN FACT, IT IS
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ALMOST GUARANTEED THAT THEY'LL CHANGE OR DISAPPEAR IN A FUTURE GMP RELEASE.
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Copyright 2006, 2009, 2011, 2012, 2017 Free Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of either:
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* the GNU Lesser General Public License as published by the Free
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Software Foundation; either version 3 of the License, or (at your
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option) any later version.
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or
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* the GNU General Public License as published by the Free Software
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Foundation; either version 2 of the License, or (at your option) any
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later version.
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or both in parallel, as here.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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for more details.
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You should have received copies of the GNU General Public License and the
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GNU Lesser General Public License along with the GNU MP Library. If not,
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see https://www.gnu.org/licenses/. */
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#include "gmp-impl.h"
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/* Computes a binary quotient of size qn = un - dn.
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Output:
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Q = -U * D^{-1} mod B^qn,
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R = (U + Q * D) * B^(-qn)
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Stores the dn least significant limbs of R at {up + un - dn, dn},
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and returns the carry from the addition N + Q*D.
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D must be odd. dinv is (-D)^-1 mod B. */
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mp_limb_t
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mpn_sbpi1_bdiv_qr (mp_ptr qp,
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mp_ptr up, mp_size_t un,
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mp_srcptr dp, mp_size_t dn, mp_limb_t dinv)
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{
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mp_size_t i;
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mp_limb_t cy;
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ASSERT (dn > 0);
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ASSERT (un > dn);
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ASSERT ((dp[0] & 1) != 0);
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ASSERT (-(dp[0] * dinv) == 1);
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ASSERT (up == qp || !MPN_OVERLAP_P (up, un, qp, un - dn));
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for (i = un - dn, cy = 0; i != 0; i--)
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{
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mp_limb_t q = dinv * up[0];
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mp_limb_t hi = mpn_addmul_1 (up, dp, dn, q);
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*qp++ = q;
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hi += cy;
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cy = hi < cy;
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hi += up[dn];
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cy += hi < up[dn];
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up[dn] = hi;
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up++;
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}
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return cy;
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}
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