divrem.c
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上传日期:2022-08-06
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- /* mpn_divrem -- Divide natural numbers, producing both remainder and
- quotient. This is now just a middle layer for calling the new
- internal mpn_tdiv_qr.
- Copyright 1993, 1994, 1995, 1996, 1997, 1999, 2000, 2001, 2002, 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"
- #include "longlong.h"
- mp_limb_t
- mpn_divrem (mp_ptr qp, mp_size_t qxn,
- mp_ptr np, mp_size_t nn,
- mp_srcptr dp, mp_size_t dn)
- {
- ASSERT (qxn >= 0);
- ASSERT (nn >= dn);
- ASSERT (dn >= 1);
- ASSERT (dp[dn-1] & GMP_NUMB_HIGHBIT);
- ASSERT (! MPN_OVERLAP_P (np, nn, dp, dn));
- ASSERT (! MPN_OVERLAP_P (qp, nn-dn+qxn, np, nn) || qp==np+dn+qxn);
- ASSERT (! MPN_OVERLAP_P (qp, nn-dn+qxn, dp, dn));
- ASSERT_MPN (np, nn);
- ASSERT_MPN (dp, dn);
- if (dn == 1)
- {
- mp_limb_t ret;
- mp_ptr q2p;
- mp_size_t qn;
- TMP_DECL;
- TMP_MARK;
- q2p = TMP_ALLOC_LIMBS (nn + qxn);
- np[0] = mpn_divrem_1 (q2p, qxn, np, nn, dp[0]);
- qn = nn + qxn - 1;
- MPN_COPY (qp, q2p, qn);
- ret = q2p[qn];
- TMP_FREE;
- return ret;
- }
- else if (dn == 2)
- {
- return mpn_divrem_2 (qp, qxn, np, nn, dp);
- }
- else
- {
- mp_ptr rp, q2p;
- mp_limb_t qhl;
- mp_size_t qn;
- TMP_DECL;
- TMP_MARK;
- if (UNLIKELY (qxn != 0))
- {
- mp_ptr n2p;
- n2p = TMP_ALLOC_LIMBS (nn + qxn);
- MPN_ZERO (n2p, qxn);
- MPN_COPY (n2p + qxn, np, nn);
- q2p = TMP_ALLOC_LIMBS (nn - dn + qxn + 1);
- rp = TMP_ALLOC_LIMBS (dn);
- mpn_tdiv_qr (q2p, rp, 0L, n2p, nn + qxn, dp, dn);
- MPN_COPY (np, rp, dn);
- qn = nn - dn + qxn;
- MPN_COPY (qp, q2p, qn);
- qhl = q2p[qn];
- }
- else
- {
- q2p = TMP_ALLOC_LIMBS (nn - dn + 1);
- rp = TMP_ALLOC_LIMBS (dn);
- mpn_tdiv_qr (q2p, rp, 0L, np, nn, dp, dn);
- MPN_COPY (np, rp, dn); /* overwrite np area with remainder */
- qn = nn - dn;
- MPN_COPY (qp, q2p, qn);
- qhl = q2p[qn];
- }
- TMP_FREE;
- return qhl;
- }
- }