github.com/aergoio/aergo@v1.3.1/libtool/src/gmp-6.1.2/mpz/cdiv_r_ui.c (about)

     1  /* mpz_cdiv_r_ui -- Division rounding the quotient towards +infinity.  The
     2     remainder gets the opposite sign as the denominator.  In order to make it
     3     always fit into the return type, the negative of the true remainder is
     4     returned.
     5  
     6  Copyright 1994-1996, 2001, 2002, 2004, 2005, 2012 Free Software Foundation,
     7  Inc.
     8  
     9  This file is part of the GNU MP Library.
    10  
    11  The GNU MP Library is free software; you can redistribute it and/or modify
    12  it under the terms of either:
    13  
    14    * the GNU Lesser General Public License as published by the Free
    15      Software Foundation; either version 3 of the License, or (at your
    16      option) any later version.
    17  
    18  or
    19  
    20    * the GNU General Public License as published by the Free Software
    21      Foundation; either version 2 of the License, or (at your option) any
    22      later version.
    23  
    24  or both in parallel, as here.
    25  
    26  The GNU MP Library is distributed in the hope that it will be useful, but
    27  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    28  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
    29  for more details.
    30  
    31  You should have received copies of the GNU General Public License and the
    32  GNU Lesser General Public License along with the GNU MP Library.  If not,
    33  see https://www.gnu.org/licenses/.  */
    34  
    35  #include "gmp.h"
    36  #include "gmp-impl.h"
    37  
    38  unsigned long int
    39  mpz_cdiv_r_ui (mpz_ptr rem, mpz_srcptr dividend, unsigned long int divisor)
    40  {
    41    mp_size_t ns, nn;
    42    mp_ptr np;
    43    mp_limb_t rl;
    44  
    45    if (UNLIKELY (divisor == 0))
    46      DIVIDE_BY_ZERO;
    47  
    48    ns = SIZ(dividend);
    49    if (ns == 0)
    50      {
    51        SIZ(rem) = 0;
    52        return 0;
    53      }
    54  
    55    nn = ABS(ns);
    56    np = PTR(dividend);
    57  #if BITS_PER_ULONG > GMP_NUMB_BITS  /* avoid warnings about shift amount */
    58    if (divisor > GMP_NUMB_MAX)
    59      {
    60        mp_limb_t dp[2];
    61        mp_ptr rp, qp;
    62        mp_size_t rn;
    63        TMP_DECL;
    64  
    65        rp = MPZ_REALLOC (rem, 2);
    66  
    67        if (nn == 1)		/* tdiv_qr requirements; tested above for 0 */
    68  	{
    69  	  rl = np[0];
    70  	  rp[0] = rl;
    71  	}
    72        else
    73  	{
    74  	  TMP_MARK;
    75  	  dp[0] = divisor & GMP_NUMB_MASK;
    76  	  dp[1] = divisor >> GMP_NUMB_BITS;
    77  	  qp = TMP_ALLOC_LIMBS (nn - 2 + 1);
    78  	  mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
    79  	  TMP_FREE;
    80  	  rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
    81  	}
    82  
    83        if (rl != 0 && ns >= 0)
    84  	{
    85  	  rl = divisor - rl;
    86  	  rp[0] = rl & GMP_NUMB_MASK;
    87  	  rp[1] = rl >> GMP_NUMB_BITS;
    88  	}
    89  
    90        rn = 1 + (rl > GMP_NUMB_MAX);  rn -= (rp[rn - 1] == 0);
    91        SIZ(rem) = -rn;
    92      }
    93    else
    94  #endif
    95      {
    96        rl = mpn_mod_1 (np, nn, (mp_limb_t) divisor);
    97        if (rl == 0)
    98  	SIZ(rem) = 0;
    99        else
   100  	{
   101  	  if (ns >= 0)
   102  	    rl = divisor - rl;
   103  
   104  	  PTR(rem)[0] = rl;
   105  	  SIZ(rem) = -1;
   106  	}
   107      }
   108  
   109    return rl;
   110  }