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/* mpfr_set_si -- set a MPFR number from a machine signed integer
Copyright 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
This file is part of the MPFR Library.
The 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 2.1 of the License, or (at your
option) any later version.
The 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 MPFR Library; see the file COPYING.LIB. If not, 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) (mpfr_ptr x, long i, mp_rnd_t rnd_mode)
{
int inex;
mp_size_t xn;
unsigned int cnt, nbits;
mp_limb_t ai, *xp;
MPFR_CLEAR_FLAGS(x);
if (i == 0)
{
MPFR_SET_ZERO(x);
MPFR_SET_POS(x);
MPFR_RET(0);
}
xn = (MPFR_PREC(x)-1)/BITS_PER_MP_LIMB;
ai = SAFE_ABS(unsigned long, i);
MPFR_ASSERTN(SAFE_ABS(unsigned long, i) == ai);
count_leading_zeros(cnt, ai);
xp = MPFR_MANT(x);
xp[xn] = ai << cnt;
/* don't forget to put zero in lower limbs */
MPN_ZERO(xp, xn);
/* set sign */
if (i < 0)
MPFR_SET_NEG(x);
else
MPFR_SET_POS(x);
nbits = BITS_PER_MP_LIMB - cnt;
MPFR_EXP (x) = nbits; /* may be out-of-range, check range below */
inex = mpfr_check_range(x, 0, rnd_mode);
if (inex)
return inex; /* underflow or overflow */
/* round if MPFR_PREC(x) smaller than length of i */
if (MPFR_UNLIKELY(MPFR_PREC(x) < nbits))
{
int carry;
carry = mpfr_round_raw(xp+xn, xp+xn, nbits, (i < 0), MPFR_PREC(x),
rnd_mode, &inex);
if (MPFR_UNLIKELY(carry))
{
/* nbits is the current exponent */
if (MPFR_UNLIKELY((mp_exp_t) nbits == __gmpfr_emax))
return mpfr_overflow(x, rnd_mode, (i < 0 ? -1 : 1));
MPFR_SET_EXP (x, nbits + 1);
xp[xn] = MPFR_LIMB_HIGHBIT;
}
}
MPFR_RET(inex);
}
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