1 /* mpz_mul_2exp -- Multiply a bignum by 2**CNT
3 Copyright 1991, 1993, 1994, 1996, 2001, 2002 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 Lesser General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or (at your
10 option) any later version.
12 The GNU MP Library is distributed in the hope that it will be useful, but
13 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
15 License for more details.
17 You should have received a copy of the GNU Lesser General Public License
18 along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
24 mpz_mul_2exp (mpz_ptr w
, mpz_srcptr u
, mp_bitcnt_t cnt
)
26 mp_size_t usize
= u
->_mp_size
;
27 mp_size_t abs_usize
= ABS (usize
);
39 limb_cnt
= cnt
/ GMP_NUMB_BITS
;
40 wsize
= abs_usize
+ limb_cnt
+ 1;
41 if (w
->_mp_alloc
< wsize
)
42 _mpz_realloc (w
, wsize
);
45 wsize
= abs_usize
+ limb_cnt
;
50 wlimb
= mpn_lshift (wp
+ limb_cnt
, u
->_mp_d
, abs_usize
, cnt
);
59 MPN_COPY_DECR (wp
+ limb_cnt
, u
->_mp_d
, abs_usize
);
62 /* Zero all whole limbs at low end. Do it here and not before calling
63 mpn_lshift, not to lose for U == W. */
64 MPN_ZERO (wp
, limb_cnt
);
66 w
->_mp_size
= usize
>= 0 ? wsize
: -wsize
;