57 lines
1.7 KiB
C
57 lines
1.7 KiB
C
/*=============================================================================
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This file is part of FLINT.
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FLINT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FLINT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FLINT; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2010 Fredrik Johansson
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******************************************************************************/
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#include <gmp.h>
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#include "flint.h"
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#include "mpn_extras.h"
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mp_size_t flint_mpn_remove_2exp(mp_ptr x, mp_size_t xsize, mp_bitcnt_t *bits)
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{
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mp_size_t shift_limbs, reduced_size;
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mp_bitcnt_t shift_bits;
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*bits = mpn_scan1(x, 0);
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if (*bits == 0)
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return xsize;
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shift_limbs = *bits / FLINT_BITS;
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shift_bits = *bits % FLINT_BITS;
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reduced_size = xsize - shift_limbs;
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if (shift_bits)
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{
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mpn_rshift(x, x + shift_limbs, reduced_size, shift_bits);
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if (x[reduced_size - 1] == 0)
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reduced_size -= 1;
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}
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else
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{
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flint_mpn_copyi(x, x + shift_limbs, reduced_size);
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}
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return reduced_size;
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}
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