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