1 /* mpz_mul_2exp -- Multiply a bignum by 2**CNT
3 Copyright (C) 1991 Free Software Foundation, Inc.
5 This file is part of the GNU MP Library.
7 The GNU MP Library is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 The GNU MP Library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with the GNU MP Library; see the file COPYING. If not, write to
19 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
26 mpz_mul_2exp (MP_INT *w, const MP_INT *u, unsigned long int cnt)
28 mpz_mul_2exp (w, u, cnt)
31 unsigned long int cnt;
34 mp_size usize = u->size;
35 mp_size abs_usize = ABS (usize);
47 limb_cnt = cnt / BITS_PER_MP_LIMB;
48 wsize = abs_usize + limb_cnt + 1;
50 _mpz_realloc (w, wsize);
53 wdigit = mpn_lshift (wp + limb_cnt, u->d, abs_usize,
54 cnt % BITS_PER_MP_LIMB);
55 wsize = abs_usize + limb_cnt;
63 /* Zero all whole digits at low end. Do it here and not before calling
64 mpn_lshift, not to loose for U == W. */
65 MPN_ZERO (wp, limb_cnt);
67 w->size = (usize >= 0) ? wsize : -wsize;