sub_n.c
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上传日期:2022-08-06
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- /* mpn_sub_n -- Subtract equal length limb vectors.
- Copyright 1992, 1993, 1994, 1996, 2000, 2002, 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"
- #if GMP_NAIL_BITS == 0
- mp_limb_t
- mpn_sub_n (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n)
- {
- mp_limb_t ul, vl, sl, rl, cy, cy1, cy2;
- ASSERT (n >= 1);
- ASSERT (MPN_SAME_OR_INCR_P (rp, up, n));
- ASSERT (MPN_SAME_OR_INCR_P (rp, vp, n));
- cy = 0;
- do
- {
- ul = *up++;
- vl = *vp++;
- sl = ul - vl;
- cy1 = sl > ul;
- rl = sl - cy;
- cy2 = rl > sl;
- cy = cy1 | cy2;
- *rp++ = rl;
- }
- while (--n != 0);
- return cy;
- }
- #endif
- #if GMP_NAIL_BITS >= 1
- mp_limb_t
- mpn_sub_n (mp_ptr rp, mp_srcptr up, mp_srcptr vp, mp_size_t n)
- {
- mp_limb_t ul, vl, rl, cy;
- ASSERT (n >= 1);
- ASSERT (MPN_SAME_OR_INCR_P (rp, up, n));
- ASSERT (MPN_SAME_OR_INCR_P (rp, vp, n));
- cy = 0;
- do
- {
- ul = *up++;
- vl = *vp++;
- rl = ul - vl - cy;
- cy = rl >> (GMP_LIMB_BITS - 1);
- *rp++ = rl & GMP_NUMB_MASK;
- }
- while (--n != 0);
- return cy;
- }
- #endif