58 lines
1.8 KiB
C
58 lines
1.8 KiB
C
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/* mpf_set_prec(x) -- Change the precision of x.
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Copyright (C) 1993, 1994, 1995 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 Library General Public License as published by
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the Free Software Foundation; either version 2 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 Library General Public
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License for more details.
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You should have received a copy of the GNU Library 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., 59 Temple Place - Suite 330, Boston,
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MA 02111-1307, 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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#if __STDC__
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mpf_set_prec (mpf_ptr x, unsigned long int prec_in_bits)
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#else
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mpf_set_prec (x, prec_in_bits)
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mpf_ptr x;
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unsigned long int prec_in_bits;
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#endif
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{
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mp_size_t prec;
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mp_size_t size = ABS (x->_mp_size);
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prec = (MAX (53, prec_in_bits) + 2 * BITS_PER_MP_LIMB - 1)/BITS_PER_MP_LIMB;
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/* We want the most significant limbs, so move the limbs down if we are
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about to truncate the value. */
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if (size > prec + 1)
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{
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mp_size_t offset = size - (prec + 1);
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mp_ptr xp = x->_mp_d;
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MPN_COPY (xp, xp + offset, prec + 1);
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}
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x->_mp_d = (mp_ptr) (*_mp_reallocate_func)
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(x->_mp_d,
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(x->_mp_prec + 1) * BYTES_PER_MP_LIMB, (prec + 1) * BYTES_PER_MP_LIMB);
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x->_mp_prec = prec;
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/* If the precision decreased, truncate the number. */
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if (size > prec + 1)
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x->_mp_size = x->_mp_size >= 0 ? (prec + 1) : -(prec + 1);
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}
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