1/* mpz_tdiv_r_2exp -- Divide an integer by 2**CNT and produce a remainder.
2
3Copyright 1991, 1993-1995, 2001, 2002, 2012 Free Software Foundation, Inc.
4
5This file is part of the GNU MP Library.
6
7The GNU MP Library is free software; you can redistribute it and/or modify
8it 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
14or
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
20or both in parallel, as here.
21
22The GNU MP Library is distributed in the hope that it will be useful, but
23WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
24or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
25for more details.
26
27You should have received copies of the GNU General Public License and the
28GNU Lesser General Public License along with the GNU MP Library.  If not,
29see https://www.gnu.org/licenses/.  */
30
31#include "gmp-impl.h"
32
33void
34mpz_tdiv_r_2exp (mpz_ptr res, mpz_srcptr in, mp_bitcnt_t cnt)
35{
36  mp_size_t in_size = ABSIZ (in);
37  mp_size_t res_size;
38  mp_size_t limb_cnt = cnt / GMP_NUMB_BITS;
39  mp_srcptr in_ptr = PTR (in);
40
41  if (in_size > limb_cnt)
42    {
43      /* The input operand is (probably) greater than 2**CNT.  */
44      mp_limb_t x;
45
46      x = in_ptr[limb_cnt] & (((mp_limb_t) 1 << cnt % GMP_NUMB_BITS) - 1);
47      if (x != 0)
48	{
49	  res_size = limb_cnt + 1;
50	  MPZ_REALLOC (res, res_size);
51
52	  PTR (res)[limb_cnt] = x;
53	}
54      else
55	{
56	  MPN_NORMALIZE (in_ptr, limb_cnt);
57
58	  MPZ_REALLOC (res, limb_cnt);
59
60	  res_size = limb_cnt;
61	}
62    }
63  else
64    {
65      /* The input operand is smaller than 2**CNT.  We perform a no-op,
66	 apart from that we might need to copy IN to RES.  */
67      limb_cnt = in_size;
68      MPZ_REALLOC (res, limb_cnt);
69
70      res_size = limb_cnt;
71    }
72
73  if (res != in)
74    MPN_COPY (PTR (res), PTR (in), limb_cnt);
75  SIZ (res) = SIZ (in) >= 0 ? res_size : -res_size;
76}
77