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/* mpfr_set_si -- set a MPFR number from a machine signed integer
Copyright (C) 1999-2001 Free Software Foundation.
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 Library General Public License as published by
the Free Software Foundation; either version 2 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 Library General Public
License for more details.
You should have received a copy of the GNU Library General Public License
along with the MPFR Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include "gmp.h"
#include "gmp-impl.h"
#include "longlong.h"
#include "mpfr.h"
#include "mpfr-impl.h"
int
#if __STDC__
mpfr_set_si (mpfr_ptr x, long i, mp_rnd_t rnd_mode)
#else
mpfr_set_si (x, i, rnd_mode)
mpfr_ptr x;
long i;
mp_rnd_t rnd_mode;
#endif
{
int inex = 0;
mp_size_t xn;
unsigned int cnt, nbits;
mp_limb_t ai, *xp;
MPFR_CLEAR_FLAGS(x);
if (i == 0)
{
MPFR_SET_ZERO(x);
if (MPFR_SIGN(x) < 0) MPFR_CHANGE_SIGN(x);
return 0;
}
xn = (MPFR_PREC(x)-1)/BITS_PER_MP_LIMB;
ai = SAFE_ABS(long, i);
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);
MPFR_EXP(x) = nbits = BITS_PER_MP_LIMB - cnt;
/* round if MPFR_PREC(x) smaller than length of i */
if (MPFR_PREC(x) < nbits)
{
int carry;
carry = mpfr_round_raw(xp+xn, xp+xn, nbits, (i < 0), MPFR_PREC(x),
rnd_mode, &inex);
if (carry)
{
mp_exp_t exp = MPFR_EXP(x);
if (exp == __mpfr_emax)
return mpfr_set_overflow(x, rnd_mode, (ai < 0 ? -1 : 1));
MPFR_EXP(x)++;
xp[xn] = MP_LIMB_T_HIGHBIT;
}
}
/* warning: don't change the precision of x! */
if ((i < 0) ^ (MPFR_SIGN(x) < 0)) MPFR_CHANGE_SIGN(x);
MPFR_RET(inex);
}
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