62 lines
1.7 KiB
C
62 lines
1.7 KiB
C
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/* mpz_tdiv_q_2exp -- Divide an integer by 2**CNT. Round the quotient
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towards -infinity.
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Copyright 1991, 1993, 1994, 1996, 2001, 2002 Free Software Foundation, 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 the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or (at your
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option) any later version.
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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 Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the GNU MP Library; see the file COPYING.LIB. If not, write to
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the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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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_tdiv_q_2exp (mpz_ptr w, mpz_srcptr u, unsigned long int cnt)
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{
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mp_size_t usize, wsize;
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mp_size_t limb_cnt;
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usize = u->_mp_size;
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limb_cnt = cnt / GMP_NUMB_BITS;
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wsize = ABS (usize) - limb_cnt;
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if (wsize <= 0)
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w->_mp_size = 0;
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else
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{
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mp_ptr wp;
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mp_srcptr up;
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if (w->_mp_alloc < wsize)
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_mpz_realloc (w, wsize);
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wp = w->_mp_d;
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up = u->_mp_d;
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cnt %= GMP_NUMB_BITS;
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if (cnt != 0)
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{
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mpn_rshift (wp, up + limb_cnt, wsize, cnt);
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wsize -= wp[wsize - 1] == 0;
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}
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else
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{
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MPN_COPY_INCR (wp, up + limb_cnt, wsize);
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}
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w->_mp_size = usize >= 0 ? wsize : -wsize;
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}
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}
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