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/* mpfr_set_f -- set a MPFR number from a GNU MPF number
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 Place, Fifth Floor, Boston,
MA 02110-1301, USA. */
#define MPFR_NEED_LONGLONG_H
#include "mpfr-impl.h"
int
mpfr_set_f (mpfr_ptr y, mpf_srcptr x, mp_rnd_t rnd_mode)
{
mp_limb_t *my, *mx, *tmp;
unsigned long cnt, sx, sy;
int inexact, carry = 0;
MPFR_TMP_DECL(marker);
sx = ABS(SIZ(x)); /* number of limbs of the mantissa of x */
if (sx == 0) /* x is zero */
{
MPFR_CLEAR_FLAGS (y);
MPFR_SET_ZERO(y);
MPFR_SET_POS(y);
return 0; /* 0 is exact */
}
if (SIZ(x) * MPFR_FROM_SIGN_TO_INT(MPFR_SIGN(y)) < 0)
MPFR_CHANGE_SIGN (y);
MPFR_CLEAR_FLAGS (y);
sy = 1 + (MPFR_PREC(y) - 1) / BITS_PER_MP_LIMB;
my = MPFR_MANT(y);
mx = PTR(x);
count_leading_zeros(cnt, mx[sx - 1]);
if (sy <= sx) /* we may have to round even when sy = sx */
{
unsigned long xprec = sx * BITS_PER_MP_LIMB;
MPFR_TMP_MARK(marker);
tmp = (mp_limb_t*) MPFR_TMP_ALLOC(sx * BYTES_PER_MP_LIMB);
if (cnt)
mpn_lshift (tmp, mx, sx, cnt);
else
/* FIXME: we may avoid the copy here, and directly call mpfr_round_raw
on mx instead of tmp */
MPN_COPY (tmp, mx, sx);
carry = mpfr_round_raw (my, tmp, xprec, (SIZ(x) < 0), MPFR_PREC(y),
rnd_mode, &inexact);
if (MPFR_UNLIKELY(carry)) /* result is a power of two */
my[sy - 1] = MPFR_LIMB_HIGHBIT;
MPFR_TMP_FREE(marker);
}
else
{
if (cnt)
mpn_lshift (my + sy - sx, mx, sx, cnt);
else
MPN_COPY (my + sy - sx, mx, sx);
MPN_ZERO(my, sy - sx);
/* no rounding necessary, since y has a larger mantissa */
inexact = 0;
}
/* warning: EXP(x) * BITS_PER_MP_LIMB may exceed the maximal exponent */
if (EXP(x) > 1 + (__mpfr_emax - 1) / BITS_PER_MP_LIMB)
{
/* EXP(x) >= 2 + floor((__mpfr_emax-1)/BITS_PER_MP_LIMB)
EXP(x) >= 2 + (__mpfr_emax - BITS_PER_MP_LIMB) / BITS_PER_MP_LIMB
>= 1 + __mpfr_emax / BITS_PER_MP_LIMB
EXP(x) * BITS_PER_MP_LIMB >= __mpfr_emax + BITS_PER_MP_LIMB
Since 0 <= cnt <= BITS_PER_MP_LIMB-1, and 0 <= carry <= 1,
we have then EXP(x) * BITS_PER_MP_LIMB - cnt + carry > __mpfr_emax */
return mpfr_overflow (y, rnd_mode, MPFR_SIGN (y));
}
else
MPFR_SET_EXP(y, EXP(x) * BITS_PER_MP_LIMB - (mp_exp_t) cnt + carry);
return mpfr_check_range (y, inexact, rnd_mode);
}
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