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

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