1/* mpz_tdiv_q_2exp -- Divide an integer by 2**CNT.  Round the quotient
2   towards -infinity.
3
4Copyright 1991, 1993, 1994, 1996, 2001, 2002, 2012 Free Software Foundation,
5Inc.
6
7This file is part of the GNU MP Library.
8
9The GNU MP Library is free software; you can redistribute it and/or modify
10it 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
16or
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
22or both in parallel, as here.
23
24The GNU MP Library is distributed in the hope that it will be useful, but
25WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
26or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
27for more details.
28
29You should have received copies of the GNU General Public License and the
30GNU Lesser General Public License along with the GNU MP Library.  If not,
31see https://www.gnu.org/licenses/.  */
32
33#include "gmp-impl.h"
34
35void
36mpz_tdiv_q_2exp (mpz_ptr r, mpz_srcptr u, mp_bitcnt_t cnt)
37{
38  mp_size_t un, rn;
39  mp_size_t limb_cnt;
40  mp_ptr rp;
41  mp_srcptr up;
42
43  un = SIZ(u);
44  limb_cnt = cnt / GMP_NUMB_BITS;
45  rn = ABS (un) - limb_cnt;
46
47  if (rn <= 0)
48    rn = 0;
49  else
50    {
51      rp = MPZ_REALLOC (r, rn);
52      up = PTR(u) + limb_cnt;
53
54      cnt %= GMP_NUMB_BITS;
55      if (cnt != 0)
56	{
57	  mpn_rshift (rp, up, rn, cnt);
58	  rn -= rp[rn - 1] == 0;
59	}
60      else
61	{
62	  MPN_COPY_INCR (rp, up, rn);
63	}
64    }
65
66  SIZ(r) = un >= 0 ? rn : -rn;
67}
68