102 lines
2.8 KiB
C
102 lines
2.8 KiB
C
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/* mpn_divrem -- Divide natural numbers, producing both remainder and
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quotient. This is now just a middle layer for calling the new
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internal mpn_tdiv_qr.
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Copyright 1993, 1994, 1995, 1996, 1997, 1999, 2000, 2001, 2002, 2005 Free
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Software Foundation, Inc.
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This file is part of the GNU MP Library.
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The GNU MP Library is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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The GNU MP Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include "mpir.h"
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#include "gmp-impl.h"
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#include "longlong.h"
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mp_limb_t
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mpn_divrem (mp_ptr qp, mp_size_t qxn,
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mp_ptr np, mp_size_t nn,
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mp_srcptr dp, mp_size_t dn)
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{
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ASSERT (qxn >= 0);
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ASSERT (nn >= dn);
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ASSERT (dn >= 1);
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ASSERT (dp[dn-1] & GMP_NUMB_HIGHBIT);
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ASSERT (! MPN_OVERLAP_P (np, nn, dp, dn));
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ASSERT (! MPN_OVERLAP_P (qp, nn-dn+qxn, np, nn) || qp==np+dn+qxn);
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ASSERT (! MPN_OVERLAP_P (qp, nn-dn+qxn, dp, dn));
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ASSERT_MPN (np, nn);
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ASSERT_MPN (dp, dn);
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if (dn == 1)
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{
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mp_limb_t ret;
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mp_ptr q2p;
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mp_size_t qn;
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TMP_DECL;
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TMP_MARK;
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q2p = (mp_ptr) TMP_ALLOC ((nn + qxn) * BYTES_PER_MP_LIMB);
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np[0] = mpn_divrem_1 (q2p, qxn, np, nn, dp[0]);
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qn = nn + qxn - 1;
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MPN_COPY (qp, q2p, qn);
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ret = q2p[qn];
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TMP_FREE;
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return ret;
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}
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else if (dn == 2)
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{
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return mpn_divrem_2 (qp, qxn, np, nn, dp);
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}
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else
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{
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mp_ptr rp, q2p;
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mp_limb_t qhl;
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mp_size_t qn;
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TMP_DECL;
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TMP_MARK;
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if (UNLIKELY (qxn != 0))
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{
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mp_ptr n2p;
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n2p = (mp_ptr) TMP_ALLOC ((nn + qxn) * BYTES_PER_MP_LIMB);
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MPN_ZERO (n2p, qxn);
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MPN_COPY (n2p + qxn, np, nn);
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q2p = (mp_ptr) TMP_ALLOC ((nn - dn + qxn + 1) * BYTES_PER_MP_LIMB);
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rp = (mp_ptr) TMP_ALLOC (dn * BYTES_PER_MP_LIMB);
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mpn_tdiv_qr (q2p, rp, 0L, n2p, nn + qxn, dp, dn);
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MPN_COPY (np, rp, dn);
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qn = nn - dn + qxn;
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MPN_COPY (qp, q2p, qn);
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qhl = q2p[qn];
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}
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else
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{
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q2p = (mp_ptr) TMP_ALLOC ((nn - dn + 1) * BYTES_PER_MP_LIMB);
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rp = (mp_ptr) TMP_ALLOC (dn * BYTES_PER_MP_LIMB);
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mpn_tdiv_qr (q2p, rp, 0L, np, nn, dp, dn);
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MPN_COPY (np, rp, dn); /* overwrite np area with remainder */
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qn = nn - dn;
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MPN_COPY (qp, q2p, qn);
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qhl = q2p[qn];
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}
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TMP_FREE;
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return qhl;
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}
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}
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