14a238c70SJohn Marino /* mpfr_fits_*_p -- test whether an mpfr fits a C unsigned type.
24a238c70SJohn Marino
3*ab6d115fSJohn Marino Copyright 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc.
4*ab6d115fSJohn Marino Contributed by the AriC and Caramel projects, INRIA.
54a238c70SJohn Marino
64a238c70SJohn Marino This file is part of the GNU MPFR Library.
74a238c70SJohn Marino
84a238c70SJohn Marino The GNU MPFR Library is free software; you can redistribute it and/or modify
94a238c70SJohn Marino it under the terms of the GNU Lesser General Public License as published by
104a238c70SJohn Marino the Free Software Foundation; either version 3 of the License, or (at your
114a238c70SJohn Marino option) any later version.
124a238c70SJohn Marino
134a238c70SJohn Marino The GNU MPFR Library is distributed in the hope that it will be useful, but
144a238c70SJohn Marino WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
154a238c70SJohn Marino or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
164a238c70SJohn Marino License for more details.
174a238c70SJohn Marino
184a238c70SJohn Marino You should have received a copy of the GNU Lesser General Public License
194a238c70SJohn Marino along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
204a238c70SJohn Marino http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
214a238c70SJohn Marino 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
224a238c70SJohn Marino
234a238c70SJohn Marino #include "mpfr-impl.h"
244a238c70SJohn Marino
254a238c70SJohn Marino int
FUNCTION(mpfr_srcptr f,mpfr_rnd_t rnd)264a238c70SJohn Marino FUNCTION (mpfr_srcptr f, mpfr_rnd_t rnd)
274a238c70SJohn Marino {
284a238c70SJohn Marino mpfr_exp_t e;
294a238c70SJohn Marino int prec;
304a238c70SJohn Marino TYPE s;
314a238c70SJohn Marino mpfr_t x;
324a238c70SJohn Marino int res;
334a238c70SJohn Marino
344a238c70SJohn Marino if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (f)))
354a238c70SJohn Marino /* Zero always fit */
364a238c70SJohn Marino return MPFR_IS_ZERO (f) ? 1 : 0;
374a238c70SJohn Marino else if (MPFR_IS_NEG (f))
384a238c70SJohn Marino /* Negative numbers don't fit */
394a238c70SJohn Marino return 0;
404a238c70SJohn Marino /* now it fits if
414a238c70SJohn Marino (a) f <= MAXIMUM
424a238c70SJohn Marino (b) round(f, prec(slong), rnd) <= MAXIMUM */
434a238c70SJohn Marino
444a238c70SJohn Marino e = MPFR_GET_EXP (f);
454a238c70SJohn Marino
464a238c70SJohn Marino /* first compute prec(MAXIMUM); fits in an int */
474a238c70SJohn Marino for (s = MAXIMUM, prec = 0; s != 0; s /= 2, prec ++);
484a238c70SJohn Marino
494a238c70SJohn Marino /* MAXIMUM needs prec bits, i.e. MAXIMUM = 2^prec - 1 */
504a238c70SJohn Marino
514a238c70SJohn Marino /* if e <= prec - 1, then f < 2^(prec-1) < MAXIMUM */
524a238c70SJohn Marino if (e <= prec - 1)
534a238c70SJohn Marino return 1;
544a238c70SJohn Marino
554a238c70SJohn Marino /* if e >= prec + 1, then f >= 2^prec > MAXIMUM */
564a238c70SJohn Marino if (e >= prec + 1)
574a238c70SJohn Marino return 0;
584a238c70SJohn Marino
594a238c70SJohn Marino MPFR_ASSERTD (e == prec);
604a238c70SJohn Marino
614a238c70SJohn Marino /* hard case: first round to prec bits, then check */
624a238c70SJohn Marino mpfr_init2 (x, prec);
634a238c70SJohn Marino mpfr_set (x, f, rnd);
644a238c70SJohn Marino res = MPFR_GET_EXP (x) == e;
654a238c70SJohn Marino mpfr_clear (x);
664a238c70SJohn Marino return res;
674a238c70SJohn Marino }
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