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      1 /* mpz_tdiv_q_2exp -- Divide an integer by 2**CNT.  Round the quotient
      2    towards -infinity.
      3 
      4 Copyright 1991, 1993, 1994, 1996, 2001, 2002, 2012 Free Software Foundation,
      5 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 void
     36 mpz_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