redc_1.c
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上传日期:2022-08-06
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- /* mpn_redc_1. Set cp[] <- up[]/R^n mod mp[]. Clobber up[].
- mp[] is n limbs; up[] is 2n limbs.
- THIS IS AN INTERNAL FUNCTION WITH A MUTABLE INTERFACE. IT IS ONLY
- SAFE TO REACH THIS FUNCTION THROUGH DOCUMENTED INTERFACES.
- Copyright (C) 2000, 2001, 2002, 2004, 2008, 2009 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"
- void
- mpn_redc_1 (mp_ptr rp, mp_ptr up, mp_srcptr mp, mp_size_t n, mp_limb_t invm)
- {
- mp_size_t j;
- mp_limb_t cy;
- ASSERT (n > 0);
- ASSERT_MPN (up, 2*n);
- for (j = n - 1; j >= 0; j--)
- {
- cy = mpn_addmul_1 (up, mp, n, (up[0] * invm) & GMP_NUMB_MASK);
- ASSERT (up[0] == 0);
- up[0] = cy;
- up++;
- }
- cy = mpn_add_n (rp, up, up - n, n);
- if (cy != 0)
- mpn_sub_n (rp, rp, mp, n);
- }