1*86d7f5d3SJohn Marino /* mpz_mul_2exp -- Multiply a bignum by 2**CNT
2*86d7f5d3SJohn Marino
3*86d7f5d3SJohn Marino Copyright 1991, 1993, 1994, 1996, 2001, 2002 Free Software Foundation, Inc.
4*86d7f5d3SJohn Marino
5*86d7f5d3SJohn Marino This file is part of the GNU MP Library.
6*86d7f5d3SJohn Marino
7*86d7f5d3SJohn Marino The GNU MP Library is free software; you can redistribute it and/or modify
8*86d7f5d3SJohn Marino it under the terms of the GNU Lesser General Public License as published by
9*86d7f5d3SJohn Marino the Free Software Foundation; either version 3 of the License, or (at your
10*86d7f5d3SJohn Marino option) any later version.
11*86d7f5d3SJohn Marino
12*86d7f5d3SJohn Marino The GNU MP Library is distributed in the hope that it will be useful, but
13*86d7f5d3SJohn Marino WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14*86d7f5d3SJohn Marino or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
15*86d7f5d3SJohn Marino License for more details.
16*86d7f5d3SJohn Marino
17*86d7f5d3SJohn Marino You should have received a copy of the GNU Lesser General Public License
18*86d7f5d3SJohn Marino along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
19*86d7f5d3SJohn Marino
20*86d7f5d3SJohn Marino #include "gmp.h"
21*86d7f5d3SJohn Marino #include "gmp-impl.h"
22*86d7f5d3SJohn Marino
23*86d7f5d3SJohn Marino void
mpz_mul_2exp(mpz_ptr w,mpz_srcptr u,mp_bitcnt_t cnt)24*86d7f5d3SJohn Marino mpz_mul_2exp (mpz_ptr w, mpz_srcptr u, mp_bitcnt_t cnt)
25*86d7f5d3SJohn Marino {
26*86d7f5d3SJohn Marino mp_size_t usize = u->_mp_size;
27*86d7f5d3SJohn Marino mp_size_t abs_usize = ABS (usize);
28*86d7f5d3SJohn Marino mp_size_t wsize;
29*86d7f5d3SJohn Marino mp_size_t limb_cnt;
30*86d7f5d3SJohn Marino mp_ptr wp;
31*86d7f5d3SJohn Marino mp_limb_t wlimb;
32*86d7f5d3SJohn Marino
33*86d7f5d3SJohn Marino if (usize == 0)
34*86d7f5d3SJohn Marino {
35*86d7f5d3SJohn Marino w->_mp_size = 0;
36*86d7f5d3SJohn Marino return;
37*86d7f5d3SJohn Marino }
38*86d7f5d3SJohn Marino
39*86d7f5d3SJohn Marino limb_cnt = cnt / GMP_NUMB_BITS;
40*86d7f5d3SJohn Marino wsize = abs_usize + limb_cnt + 1;
41*86d7f5d3SJohn Marino if (w->_mp_alloc < wsize)
42*86d7f5d3SJohn Marino _mpz_realloc (w, wsize);
43*86d7f5d3SJohn Marino
44*86d7f5d3SJohn Marino wp = w->_mp_d;
45*86d7f5d3SJohn Marino wsize = abs_usize + limb_cnt;
46*86d7f5d3SJohn Marino
47*86d7f5d3SJohn Marino cnt %= GMP_NUMB_BITS;
48*86d7f5d3SJohn Marino if (cnt != 0)
49*86d7f5d3SJohn Marino {
50*86d7f5d3SJohn Marino wlimb = mpn_lshift (wp + limb_cnt, u->_mp_d, abs_usize, cnt);
51*86d7f5d3SJohn Marino if (wlimb != 0)
52*86d7f5d3SJohn Marino {
53*86d7f5d3SJohn Marino wp[wsize] = wlimb;
54*86d7f5d3SJohn Marino wsize++;
55*86d7f5d3SJohn Marino }
56*86d7f5d3SJohn Marino }
57*86d7f5d3SJohn Marino else
58*86d7f5d3SJohn Marino {
59*86d7f5d3SJohn Marino MPN_COPY_DECR (wp + limb_cnt, u->_mp_d, abs_usize);
60*86d7f5d3SJohn Marino }
61*86d7f5d3SJohn Marino
62*86d7f5d3SJohn Marino /* Zero all whole limbs at low end. Do it here and not before calling
63*86d7f5d3SJohn Marino mpn_lshift, not to lose for U == W. */
64*86d7f5d3SJohn Marino MPN_ZERO (wp, limb_cnt);
65*86d7f5d3SJohn Marino
66*86d7f5d3SJohn Marino w->_mp_size = usize >= 0 ? wsize : -wsize;
67*86d7f5d3SJohn Marino }
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