cdiv_ui.c
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上传日期:2022-08-06
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- /* mpz_cdiv_ui -- Division rounding the quotient towards +infinity. The
- remainder gets the opposite sign as the denominator. In order to make it
- always fit into the return type, the negative of the true remainder is
- returned.
- Copyright 1994, 1995, 1996, 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"
- unsigned long int
- mpz_cdiv_ui (mpz_srcptr dividend, unsigned long int divisor)
- {
- mp_size_t ns, nn;
- mp_ptr np;
- mp_limb_t rl;
- if (divisor == 0)
- DIVIDE_BY_ZERO;
- ns = SIZ(dividend);
- if (ns == 0)
- {
- return 0;
- }
- nn = ABS(ns);
- np = PTR(dividend);
- #if BITS_PER_ULONG > GMP_NUMB_BITS /* avoid warnings about shift amount */
- if (divisor > GMP_NUMB_MAX)
- {
- mp_limb_t dp[2], rp[2];
- mp_ptr qp;
- mp_size_t rn;
- TMP_DECL;
- if (nn == 1) /* tdiv_qr requirements; tested above for 0 */
- {
- rl = np[0];
- rp[0] = rl;
- }
- else
- {
- TMP_MARK;
- dp[0] = divisor & GMP_NUMB_MASK;
- dp[1] = divisor >> GMP_NUMB_BITS;
- qp = TMP_ALLOC_LIMBS (nn - 2 + 1);
- mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
- TMP_FREE;
- rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
- }
- if (rl != 0 && ns >= 0)
- {
- rl = divisor - rl;
- rp[0] = rl & GMP_NUMB_MASK;
- rp[1] = rl >> GMP_NUMB_BITS;
- }
- rn = 1 + (rl > GMP_NUMB_MAX); rn -= (rp[rn - 1] == 0);
- }
- else
- #endif
- {
- rl = mpn_mod_1 (np, nn, (mp_limb_t) divisor);
- if (rl == 0)
- ;
- else
- {
- if (ns >= 0)
- rl = divisor - rl;
- }
- }
- return rl;
- }