github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpn/generic/divrem.c (about)

     1  /* mpn_divrem -- Divide natural numbers, producing both remainder and
     2     quotient.  This is now just a middle layer calling mpn_tdiv_qr.
     3  
     4  Copyright 1993-1997, 1999-2002, 2005 Free Software Foundation, Inc.
     5  
     6  This file is part of the GNU MP Library.
     7  
     8  The GNU MP Library is free software; you can redistribute it and/or modify
     9  it under the terms of either:
    10  
    11    * the GNU Lesser General Public License as published by the Free
    12      Software Foundation; either version 3 of the License, or (at your
    13      option) any later version.
    14  
    15  or
    16  
    17    * the GNU General Public License as published by the Free Software
    18      Foundation; either version 2 of the License, or (at your option) any
    19      later version.
    20  
    21  or both in parallel, as here.
    22  
    23  The GNU MP Library is distributed in the hope that it will be useful, but
    24  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    25  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    26  for more details.
    27  
    28  You should have received copies of the GNU General Public License and the
    29  GNU Lesser General Public License along with the GNU MP Library.  If not,
    30  see https://www.gnu.org/licenses/.  */
    31  
    32  #include "gmp.h"
    33  #include "gmp-impl.h"
    34  #include "longlong.h"
    35  
    36  mp_limb_t
    37  mpn_divrem (mp_ptr qp, mp_size_t qxn,
    38  	    mp_ptr np, mp_size_t nn,
    39  	    mp_srcptr dp, mp_size_t dn)
    40  {
    41    ASSERT (qxn >= 0);
    42    ASSERT (nn >= dn);
    43    ASSERT (dn >= 1);
    44    ASSERT (dp[dn-1] & GMP_NUMB_HIGHBIT);
    45    ASSERT (! MPN_OVERLAP_P (np, nn, dp, dn));
    46    ASSERT (! MPN_OVERLAP_P (qp, nn-dn+qxn, np, nn) || qp==np+dn+qxn);
    47    ASSERT (! MPN_OVERLAP_P (qp, nn-dn+qxn, dp, dn));
    48    ASSERT_MPN (np, nn);
    49    ASSERT_MPN (dp, dn);
    50  
    51    if (dn == 1)
    52      {
    53        mp_limb_t ret;
    54        mp_ptr q2p;
    55        mp_size_t qn;
    56        TMP_DECL;
    57  
    58        TMP_MARK;
    59        q2p = TMP_ALLOC_LIMBS (nn + qxn);
    60  
    61        np[0] = mpn_divrem_1 (q2p, qxn, np, nn, dp[0]);
    62        qn = nn + qxn - 1;
    63        MPN_COPY (qp, q2p, qn);
    64        ret = q2p[qn];
    65  
    66        TMP_FREE;
    67        return ret;
    68      }
    69    else if (dn == 2)
    70      {
    71        return mpn_divrem_2 (qp, qxn, np, nn, dp);
    72      }
    73    else
    74      {
    75        mp_ptr rp, q2p;
    76        mp_limb_t qhl;
    77        mp_size_t qn;
    78        TMP_DECL;
    79  
    80        TMP_MARK;
    81        if (UNLIKELY (qxn != 0))
    82  	{
    83  	  mp_ptr n2p;
    84  	  n2p = TMP_ALLOC_LIMBS (nn + qxn);
    85  	  MPN_ZERO (n2p, qxn);
    86  	  MPN_COPY (n2p + qxn, np, nn);
    87  	  q2p = TMP_ALLOC_LIMBS (nn - dn + qxn + 1);
    88  	  rp = TMP_ALLOC_LIMBS (dn);
    89  	  mpn_tdiv_qr (q2p, rp, 0L, n2p, nn + qxn, dp, dn);
    90  	  MPN_COPY (np, rp, dn);
    91  	  qn = nn - dn + qxn;
    92  	  MPN_COPY (qp, q2p, qn);
    93  	  qhl = q2p[qn];
    94  	}
    95        else
    96  	{
    97  	  q2p = TMP_ALLOC_LIMBS (nn - dn + 1);
    98  	  rp = TMP_ALLOC_LIMBS (dn);
    99  	  mpn_tdiv_qr (q2p, rp, 0L, np, nn, dp, dn);
   100  	  MPN_COPY (np, rp, dn);	/* overwrite np area with remainder */
   101  	  qn = nn - dn;
   102  	  MPN_COPY (qp, q2p, qn);
   103  	  qhl = q2p[qn];
   104  	}
   105        TMP_FREE;
   106        return qhl;
   107      }
   108  }