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/* mpz_mul_2exp -- Multiply a bignum by 2**CNT
Copyright 1991, 1993, 1994, 1996, 2001, 2002, 2012 Free Software Foundation,
Inc.
This file is part of the GNU MP Library.
The GNU MP Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at your
option) any later version.
The GNU MP Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the GNU MP Library. If not, see http://www.gnu.org/licenses/. */
#include "gmp.h"
#include "gmp-impl.h"
void
mpz_mul_2exp (mpz_ptr r, mpz_srcptr u, mp_bitcnt_t cnt)
{
mp_size_t un, rn;
mp_size_t limb_cnt;
mp_ptr rp;
mp_srcptr up;
mp_limb_t rlimb;
un = ABSIZ (u);
limb_cnt = cnt / GMP_NUMB_BITS;
rn = un + limb_cnt;
if (un == 0)
rn = 0;
else
{
rp = MPZ_REALLOC (r, rn + 1);
up = PTR(u);
cnt %= GMP_NUMB_BITS;
if (cnt != 0)
{
rlimb = mpn_lshift (rp + limb_cnt, up, un, cnt);
rp[rn] = rlimb;
rn += (rlimb != 0);
}
else
{
MPN_COPY_DECR (rp + limb_cnt, up, un);
}
/* Zero all whole limbs at low end. Do it here and not before calling
mpn_lshift, not to lose for U == R. */
MPN_ZERO (rp, limb_cnt);
}
SIZ(r) = SIZ(u) >= 0 ? rn : -rn;
}
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