/* mpz_tdiv_r_2exp -- Divide an integer by 2**CNT and produce a remainder.

Copyright 1991, 1993, 1994, 1995, 2001, 2002, 2012 Free Software Foundation,
Inc.

This file is part of the GNU MP Library.

The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at your
option) any later version.

The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library.  If not, see http://www.gnu.org/licenses/.  */

#include "gmp.h"
#include "gmp-impl.h"

void
mpz_tdiv_r_2exp (mpz_ptr res, mpz_srcptr in, mp_bitcnt_t cnt)
{
  mp_size_t in_size = ABSIZ (in);
  mp_size_t res_size;
  mp_size_t limb_cnt = cnt / GMP_NUMB_BITS;
  mp_srcptr in_ptr = PTR (in);

  if (in_size > limb_cnt)
    {
      /* The input operand is (probably) greater than 2**CNT.  */
      mp_limb_t x;

      x = in_ptr[limb_cnt] & (((mp_limb_t) 1 << cnt % GMP_NUMB_BITS) - 1);
      if (x != 0)
	{
	  res_size = limb_cnt + 1;
	  MPZ_REALLOC (res, res_size);

	  PTR (res)[limb_cnt] = x;
	}
      else
	{
	  res_size = limb_cnt;
	  MPN_NORMALIZE (in_ptr, res_size);

	  MPZ_REALLOC (res, res_size);

	  limb_cnt = res_size;
	}
    }
  else
    {
      /* The input operand is smaller than 2**CNT.  We perform a no-op,
	 apart from that we might need to copy IN to RES.  */
      res_size = in_size;
      MPZ_REALLOC (res, res_size);

      limb_cnt = res_size;
    }

  if (res != in)
    MPN_COPY (PTR (res), PTR (in), limb_cnt);
  SIZ (res) = SIZ (in) >= 0 ? res_size : -res_size;
}
