lcm_ui.c
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上传日期:2022-08-06
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- /* mpz_lcm_ui -- least common multiple of mpz and ulong.
- Copyright 2001, 2002, 2004 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"
- void
- mpz_lcm_ui (mpz_ptr r, mpz_srcptr u, unsigned long v)
- {
- mp_size_t usize;
- mp_srcptr up;
- mp_ptr rp;
- unsigned long g;
- mp_limb_t c;
- #if BITS_PER_ULONG > GMP_NUMB_BITS /* avoid warnings about shift amount */
- if (v > GMP_NUMB_MAX)
- {
- mpz_t vz;
- mp_limb_t vlimbs[2];
- vlimbs[0] = v & GMP_NUMB_MASK;
- vlimbs[1] = v >> GMP_NUMB_BITS;
- PTR(vz) = vlimbs;
- SIZ(vz) = 2;
- mpz_lcm (r, u, vz);
- return;
- }
- #endif
- /* result zero if either operand zero */
- usize = SIZ(u);
- if (usize == 0 || v == 0)
- {
- SIZ(r) = 0;
- return;
- }
- usize = ABS(usize);
- MPZ_REALLOC (r, usize+1);
- up = PTR(u);
- g = (unsigned long) mpn_gcd_1 (up, usize, (mp_limb_t) v);
- v /= g;
- rp = PTR(r);
- c = mpn_mul_1 (rp, up, usize, (mp_limb_t) v);
- rp[usize] = c;
- usize += (c != 0);
- SIZ(r) = usize;
- }