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