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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, 2007 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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