pre_mod_1.c
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上传日期:2022-08-06
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- /* mpn_preinv_mod_1 (up, un, d, dinv) -- Divide (UP,,UN) by the normalized D.
- DINV should be 2^(2*GMP_LIMB_BITS) / D - 2^GMP_LIMB_BITS.
- Return the single-limb remainder.
- Copyright 1991, 1993, 1994, 2000, 2001, 2002, 2004, 2005 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 "gmp.h"
- #include "gmp-impl.h"
- #include "longlong.h"
- /* This function used to be documented, but is now considered obsolete. It
- continues to exist for binary compatibility, even when not required
- internally. */
- mp_limb_t
- mpn_preinv_mod_1 (mp_srcptr up, mp_size_t un, mp_limb_t d, mp_limb_t dinv)
- {
- mp_size_t i;
- mp_limb_t n0, r;
- mp_limb_t dummy;
- ASSERT (un >= 1);
- ASSERT (d & GMP_LIMB_HIGHBIT);
- r = up[un - 1];
- if (r >= d)
- r -= d;
- for (i = un - 2; i >= 0; i--)
- {
- n0 = up[i];
- udiv_qrnnd_preinv (dummy, r, r, n0, d, dinv);
- }
- return r;
- }