1  /* mpz_divexact_ui -- exact division mpz by ulong.
       2  
       3  Copyright 2001, 2002, 2012 Free Software Foundation, Inc.
       4  
       5  This file is part of the GNU MP Library.
       6  
       7  The GNU MP Library is free software; you can redistribute it and/or modify
       8  it under the terms of either:
       9  
      10    * the GNU Lesser General Public License as published by the Free
      11      Software Foundation; either version 3 of the License, or (at your
      12      option) any later version.
      13  
      14  or
      15  
      16    * the GNU General Public License as published by the Free Software
      17      Foundation; either version 2 of the License, or (at your option) any
      18      later version.
      19  
      20  or both in parallel, as here.
      21  
      22  The GNU MP Library is distributed in the hope that it will be useful, but
      23  WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
      24  or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
      25  for more details.
      26  
      27  You should have received copies of the GNU General Public License and the
      28  GNU Lesser General Public License along with the GNU MP Library.  If not,
      29  see https://www.gnu.org/licenses/.  */
      30  
      31  #include "gmp-impl.h"
      32  
      33  void
      34  mpz_divexact_ui (mpz_ptr dst, mpz_srcptr src, unsigned long divisor)
      35  {
      36    mp_size_t  size, abs_size;
      37    mp_ptr     dst_ptr;
      38  
      39    if (UNLIKELY (divisor == 0))
      40      DIVIDE_BY_ZERO;
      41  
      42    /* For nails don't try to be clever if d is bigger than a limb, just fake
      43       up an mpz_t and go to the main mpz_divexact.  */
      44    if (divisor > GMP_NUMB_MAX)
      45      {
      46        mp_limb_t  dlimbs[2];
      47        mpz_t      dz;
      48        ALLOC(dz) = 2;
      49        PTR(dz) = dlimbs;
      50        mpz_set_ui (dz, divisor);
      51        mpz_divexact (dst, src, dz);
      52        return;
      53      }
      54  
      55    size = SIZ(src);
      56    if (size == 0)
      57      {
      58        SIZ(dst) = 0;
      59        return;
      60      }
      61    abs_size = ABS (size);
      62  
      63    dst_ptr = MPZ_REALLOC (dst, abs_size);
      64  
      65    MPN_DIVREM_OR_DIVEXACT_1 (dst_ptr, PTR(src), abs_size, (mp_limb_t) divisor);
      66    abs_size -= (dst_ptr[abs_size-1] == 0);
      67    SIZ(dst) = (size >= 0 ? abs_size : -abs_size);
      68  }