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/* mpfr_fits_intmax_p -- test whether an mpfr fits an intmax_t.
Copyright 2004, 2006, 2007 Free Software Foundation, Inc.
Contributed by the Arenaire and Cacao projects, INRIA.
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. */
#if HAVE_CONFIG_H
# include "config.h" /* for a build within gmp */
#endif
/* The ISO C99 standard specifies that in C++ implementations the
INTMAX_MAX, ... macros should only be defined if explicitly requested. */
#if defined __cplusplus
# define __STDC_LIMIT_MACROS
# define __STDC_CONSTANT_MACROS
#endif
#ifdef HAVE_STDINT_H
# include <stdint.h>
#endif
#ifdef HAVE_INTTYPES_H
# include <inttypes.h>
#endif
#include "mpfr-impl.h"
#ifdef _MPFR_H_HAVE_INTMAX_T
/* We can't use fits_s.h <= mpfr_cmp_ui */
int
mpfr_fits_intmax_p (mpfr_srcptr f, mp_rnd_t rnd)
{
mp_exp_t exp;
mp_prec_t prec;
intmax_t s;
mpfr_t x, y;
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) ? INTMAX_MIN : INTMAX_MAX;
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_init2 (y, prec);
mpfr_set (x, f, rnd);
mpfr_set_sj (y, neg ? INTMAX_MIN : INTMAX_MAX, GMP_RNDN);
res = (neg
? (mpfr_cmp (x, y) >= 0)
: (mpfr_cmp (x, y) <= 0));
mpfr_clear (y);
mpfr_clear (x);
return res;
}
#endif
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