1  /* mpz_fdiv_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-impl.h"
      34  
      35  unsigned long int
      36  mpz_fdiv_ui (mpz_srcptr dividend, unsigned long int divisor)
      37  {
      38    mp_size_t ns, nn;
      39    mp_ptr np;
      40    mp_limb_t rl;
      41  
      42    if (UNLIKELY (divisor == 0))
      43      DIVIDE_BY_ZERO;
      44  
      45    ns = SIZ(dividend);
      46    if (ns == 0)
      47      {
      48        return 0;
      49      }
      50  
      51    nn = ABS(ns);
      52    np = PTR(dividend);
      53  #if BITS_PER_ULONG > GMP_NUMB_BITS  /* avoid warnings about shift amount */
      54    if (divisor > GMP_NUMB_MAX)
      55      {
      56        mp_limb_t dp[2], rp[2];
      57        mp_ptr qp;
      58        mp_size_t rn;
      59        TMP_DECL;
      60  
      61        if (nn == 1)		/* tdiv_qr requirements; tested above for 0 */
      62  	{
      63  	  rl = np[0];
      64  	  rp[0] = rl;
      65  	}
      66        else
      67  	{
      68  	  TMP_MARK;
      69  	  dp[0] = divisor & GMP_NUMB_MASK;
      70  	  dp[1] = divisor >> GMP_NUMB_BITS;
      71  	  qp = TMP_ALLOC_LIMBS (nn - 2 + 1);
      72  	  mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
      73  	  TMP_FREE;
      74  	  rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
      75  	}
      76  
      77        if (rl != 0 && ns < 0)
      78  	{
      79  	  rl = divisor - rl;
      80  	  rp[0] = rl & GMP_NUMB_MASK;
      81  	  rp[1] = rl >> GMP_NUMB_BITS;
      82  	}
      83  
      84        rn = 1 + (rl > GMP_NUMB_MAX);  rn -= (rp[rn - 1] == 0);
      85      }
      86    else
      87  #endif
      88      {
      89        rl = mpn_mod_1 (np, nn, (mp_limb_t) divisor);
      90        if (rl == 0)
      91  	;
      92        else
      93  	{
      94  	  if (ns < 0)
      95  	    rl = divisor - rl;
      96  	}
      97      }
      98  
      99    return rl;
     100  }