1  /* mpz_cdiv_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-impl.h"
      36  
      37  unsigned long int
      38  mpz_cdiv_ui (mpz_srcptr dividend, unsigned long int divisor)
      39  {
      40    mp_size_t ns, nn;
      41    mp_ptr np;
      42    mp_limb_t rl;
      43  
      44    if (UNLIKELY (divisor == 0))
      45      DIVIDE_BY_ZERO;
      46  
      47    ns = SIZ(dividend);
      48    if (ns == 0)
      49      {
      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], rp[2];
      59        mp_ptr qp;
      60        mp_size_t rn;
      61        TMP_DECL;
      62  
      63        if (nn == 1)		/* tdiv_qr requirements; tested above for 0 */
      64  	{
      65  	  rl = np[0];
      66  	  rp[0] = rl;
      67  	}
      68        else
      69  	{
      70  	  TMP_MARK;
      71  	  dp[0] = divisor & GMP_NUMB_MASK;
      72  	  dp[1] = divisor >> GMP_NUMB_BITS;
      73  	  qp = TMP_ALLOC_LIMBS (nn - 2 + 1);
      74  	  mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
      75  	  TMP_FREE;
      76  	  rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
      77  	}
      78  
      79        if (rl != 0 && ns >= 0)
      80  	{
      81  	  rl = divisor - rl;
      82  	  rp[0] = rl & GMP_NUMB_MASK;
      83  	  rp[1] = rl >> GMP_NUMB_BITS;
      84  	}
      85  
      86        rn = 1 + (rl > GMP_NUMB_MAX);  rn -= (rp[rn - 1] == 0);
      87      }
      88    else
      89  #endif
      90      {
      91        rl = mpn_mod_1 (np, nn, (mp_limb_t) divisor);
      92        if (rl == 0)
      93  	;
      94        else
      95  	{
      96  	  if (ns >= 0)
      97  	    rl = divisor - rl;
      98  	}
      99      }
     100  
     101    return rl;
     102  }