tdiv_qr_ui.c
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上传日期:2022-08-06
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- /* mpz_tdiv_qr_ui(quot,rem,dividend,short_divisor) --
- Set QUOT to DIVIDEND / SHORT_DIVISOR
- and REM to DIVIDEND mod SHORT_DIVISOR.
- Copyright 1991, 1993, 1994, 1996, 1998, 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"
- unsigned long int
- mpz_tdiv_qr_ui (mpz_ptr quot, mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor)
- {
- mp_size_t ns, nn, qn;
- mp_ptr np, qp;
- mp_limb_t rl;
- if (divisor == 0)
- DIVIDE_BY_ZERO;
- ns = SIZ(dividend);
- if (ns == 0)
- {
- SIZ(quot) = 0;
- SIZ(rem) = 0;
- return 0;
- }
- nn = ABS(ns);
- MPZ_REALLOC (quot, nn);
- qp = PTR(quot);
- 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];
- mp_ptr rp;
- mp_size_t rn;
- if (nn == 1) /* tdiv_qr requirements; tested above for 0 */
- {
- SIZ(quot) = 0;
- rl = np[0];
- SIZ(rem) = ns >= 0 ? 1 : -1;
- PTR(rem)[0] = rl;
- return rl;
- }
- MPZ_REALLOC (rem, 2);
- rp = PTR(rem);
- dp[0] = divisor & GMP_NUMB_MASK;
- dp[1] = divisor >> GMP_NUMB_BITS;
- mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
- rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
- qn = nn - 2 + 1; qn -= qp[qn - 1] == 0; qn -= qn != 0 && qp[qn - 1] == 0;
- rn = 2 - (rp[1] == 0); rn -= (rp[rn - 1] == 0);
- SIZ(rem) = ns >= 0 ? rn : -rn;
- }
- else
- #endif
- {
- rl = mpn_divrem_1 (qp, (mp_size_t) 0, np, nn, (mp_limb_t) divisor);
- if (rl == 0)
- SIZ(rem) = 0;
- else
- {
- /* Store the single-limb remainder. We don't check if there's space
- for just one limb, since no function ever makes zero space. */
- SIZ(rem) = ns >= 0 ? 1 : -1;
- PTR(rem)[0] = rl;
- }
- qn = nn - (qp[nn - 1] == 0);
- }
- SIZ(quot) = ns >= 0 ? qn : -qn;
- return rl;
- }