| /* mpfr_fits_intmax_p -- test whether an mpfr fits an intmax_t. |
| |
| Copyright 2004, 2006, 2007, 2008, 2009 Free Software Foundation, Inc. |
| Contributed by the Arenaire and Cacao projects, INRIA. |
| |
| This file is part of the GNU MPFR Library. |
| |
| The GNU 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 GNU 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 GNU 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. */ |
| |
| #ifdef 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 |
| |
| #if HAVE_INTTYPES_H |
| # include <inttypes.h> /* for intmax_t */ |
| #else |
| # if HAVE_STDINT_H |
| # include <stdint.h> |
| # endif |
| #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 |