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/* mpf_set_prec(x) -- Change the precision of x.
Copyright 1993-1995, 2000, 2001 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 https://www.gnu.org/licenses/. */
#include "gmp.h"
#include "gmp-impl.h"
/* A full new_prec+1 limbs are always retained, even though just new_prec
would satisfy the requested precision. If size==new_prec+1 then
certainly new_prec+1 should be kept since no copying is needed in that
case. If just new_prec was kept for size>new_prec+1 it'd be a bit
inconsistent. */
void
mpf_set_prec (mpf_ptr x, mp_bitcnt_t new_prec_in_bits)
{
mp_size_t old_prec, new_prec, new_prec_plus1;
mp_size_t size, sign;
mp_ptr xp;
new_prec = __GMPF_BITS_TO_PREC (new_prec_in_bits);
old_prec = PREC(x);
/* do nothing if already the right precision */
if (new_prec == old_prec)
return;
PREC(x) = new_prec;
new_prec_plus1 = new_prec + 1;
/* retain most significant limbs */
sign = SIZ(x);
size = ABS (sign);
xp = PTR(x);
if (size > new_prec_plus1)
{
SIZ(x) = (sign >= 0 ? new_prec_plus1 : -new_prec_plus1);
MPN_COPY_INCR (xp, xp + size - new_prec_plus1, new_prec_plus1);
}
PTR(x) = __GMP_REALLOCATE_FUNC_LIMBS (xp, old_prec+1, new_prec_plus1);
}
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