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      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, 2015 Free Software
      5 Foundation, 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_r_ui (mpz_ptr rem, 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       SIZ(rem) = 0;
     49       return 0;
     50     }
     51 
     52   nn = ABS(ns);
     53   np = PTR(dividend);
     54 #if BITS_PER_ULONG > GMP_NUMB_BITS  /* avoid warnings about shift amount */
     55   if (divisor > GMP_NUMB_MAX)
     56     {
     57       mp_limb_t dp[2];
     58       mp_ptr rp, qp;
     59       mp_size_t rn;
     60       TMP_DECL;
     61 
     62       rp = MPZ_REALLOC (rem, 2);
     63 
     64       if (nn == 1)		/* tdiv_qr requirements; tested above for 0 */
     65 	{
     66 	  rl = np[0];
     67 	  rp[0] = rl;
     68 	}
     69       else
     70 	{
     71 	  TMP_MARK;
     72 	  dp[0] = divisor & GMP_NUMB_MASK;
     73 	  dp[1] = divisor >> GMP_NUMB_BITS;
     74 	  qp = TMP_ALLOC_LIMBS (nn - 2 + 1);
     75 	  mpn_tdiv_qr (qp, rp, (mp_size_t) 0, np, nn, dp, (mp_size_t) 2);
     76 	  TMP_FREE;
     77 	  rl = rp[0] + (rp[1] << GMP_NUMB_BITS);
     78 	}
     79 
     80       if (rl != 0 && ns < 0)
     81 	{
     82 	  rl = divisor - rl;
     83 	  rp[0] = rl & GMP_NUMB_MASK;
     84 	  rp[1] = rl >> GMP_NUMB_BITS;
     85 	}
     86 
     87       rn = 1 + (rl > GMP_NUMB_MAX);  rn -= (rp[rn - 1] == 0);
     88       SIZ(rem) = rn;
     89     }
     90   else
     91 #endif
     92     {
     93       rl = mpn_mod_1 (np, nn, (mp_limb_t) divisor);
     94       if (rl == 0)
     95 	SIZ(rem) = 0;
     96       else
     97 	{
     98 	  if (ns < 0)
     99 	    rl = divisor - rl;
    100 
    101 	  MPZ_NEWALLOC (rem, 1)[0] = rl;
    102 	  SIZ(rem) = 1;
    103 	}
    104     }
    105 
    106   return rl;
    107 }
    108