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/* mpfr_fits_*_p -- test whether an mpfr fits a C signed type.
Copyright 2003, 2004 Free Software Foundation.
Contributed by the Spaces project, INRIA Lorraine.
Copied from mpf/fits_s.h.
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., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */
#include "mpfr-impl.h"
int
FUNCTION (mpfr_srcptr f, mp_rnd_t rnd)
{
mp_exp_t exp;
mp_prec_t prec;
TYPE s;
mpfr_t x;
int neg;
int res;
if (MPFR_IS_NAN(f) || MPFR_IS_INF(f))
return 0; /* does not fit */
if (MPFR_IS_ZERO(f))
return 1; /* zero always fits */
/* now it fits if either
(a) MINIMUM <= f <= MAXIMUM
(b) or MINIMUM <= round(f, prec(slong), rnd) <= MAXIMUM */
exp = MPFR_EXP(f);
if (exp < 1)
return 1; /* |f| < 1: always fits */
neg = (MPFR_SIGN(f) > 0) ? 0 : 1;
/* let EXTREMUM be MAXIMUM if f > 0, and MINIMUM if f < 0 */
/* first compute prec(EXTREMUM), this could be done at configure time */
s = (neg) ? MINIMUM : MAXIMUM;
for (prec = 0; s != 0; s /= 2, prec ++);
/* EXTREMUM needs prec bits, i.e. 2^(prec-1) <= |EXTREMUM| < 2^prec */
/* if exp < prec - 1, then f < 2^(prec-1) < |EXTREMUM| */
if ((mpfr_prec_t) exp < prec - 1)
return 1;
/* if exp > prec + 1, then f >= 2^prec > EXTREMUM */
if ((mpfr_prec_t) exp > prec + 1)
return 0;
/* remains cases exp = prec-1 to prec+1 */
/* hard case: first round to prec bits, then check */
mpfr_init2 (x, prec);
mpfr_set (x, f, rnd);
res = (neg) ? (mpfr_cmp_si (x, MINIMUM) >= 0)
: (mpfr_cmp_si (x, MAXIMUM) <= 0);
mpfr_clear (x);
return res;
}
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