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/* mpfr_set_si_2exp -- set a MPFR number from a machine signed integer with
a shift
Copyright 2004, 2006-2020 Free Software Foundation, Inc.
Contributed by the AriC and Caramba projects, INRIA.
This file is part of the GNU MPFR Library.
The GNU MPFR 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 MPFR 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 MPFR Library; see the file COPYING.LESSER. If not, see
https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
#define MPFR_NEED_LONGLONG_H
#include "mpfr-impl.h"
int
mpfr_set_si_2exp (mpfr_ptr x, long i, mpfr_exp_t e, mpfr_rnd_t rnd_mode)
{
if (i == 0)
{
MPFR_SET_ZERO (x);
MPFR_SET_POS (x);
MPFR_RET (0);
}
else
{
mp_size_t xn;
int cnt, nbits;
mp_limb_t ai, *xp;
int inex = 0;
/* FIXME: support int limbs (e.g. 16-bit limbs on 16-bit proc) */
ai = SAFE_ABS (unsigned long, i);
MPFR_ASSERTN (SAFE_ABS (unsigned long, i) == ai);
/* Position of the highest limb */
xn = (MPFR_PREC (x) - 1) / GMP_NUMB_BITS;
count_leading_zeros (cnt, ai);
MPFR_ASSERTD (cnt < GMP_NUMB_BITS); /* OK since i != 0 */
xp = MPFR_MANT(x);
xp[xn] = ai << cnt;
/* Zero the xn lower limbs. */
MPN_ZERO(xp, xn);
MPFR_SET_SIGN (x, i < 0 ? MPFR_SIGN_NEG : MPFR_SIGN_POS);
nbits = GMP_NUMB_BITS - cnt;
e += nbits; /* exponent _before_ the rounding */
/* round if MPFR_PREC(x) smaller than length of i */
if (MPFR_UNLIKELY (MPFR_PREC (x) < nbits) &&
MPFR_UNLIKELY (mpfr_round_raw (xp + xn, xp + xn, nbits, i < 0,
MPFR_PREC (x), rnd_mode, &inex)))
{
e++;
xp[xn] = MPFR_LIMB_HIGHBIT;
}
MPFR_EXP (x) = e;
return mpfr_check_range (x, inex, rnd_mode);
}
}
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