1/* mpfr_fits_*_p -- test whether an mpfr fits a C unsigned type. 2 3Copyright 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc. 4Contributed by the AriC and Caramel projects, INRIA. 5 6This file is part of the GNU MPFR Library. 7 8The GNU MPFR Library is free software; you can redistribute it and/or modify 9it under the terms of the GNU Lesser General Public License as published by 10the Free Software Foundation; either version 3 of the License, or (at your 11option) any later version. 12 13The GNU MPFR Library is distributed in the hope that it will be useful, but 14WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 15or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 16License for more details. 17 18You should have received a copy of the GNU Lesser General Public License 19along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see 20http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., 2151 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */ 22 23#include "mpfr-impl.h" 24 25int 26FUNCTION (mpfr_srcptr f, mpfr_rnd_t rnd) 27{ 28 mpfr_exp_t e; 29 int prec; 30 TYPE s; 31 mpfr_t x; 32 int res; 33 34 if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (f))) 35 /* Zero always fit */ 36 return MPFR_IS_ZERO (f) ? 1 : 0; 37 else if (MPFR_IS_NEG (f)) 38 /* Negative numbers don't fit */ 39 return 0; 40 /* now it fits if 41 (a) f <= MAXIMUM 42 (b) round(f, prec(slong), rnd) <= MAXIMUM */ 43 44 e = MPFR_GET_EXP (f); 45 46 /* first compute prec(MAXIMUM); fits in an int */ 47 for (s = MAXIMUM, prec = 0; s != 0; s /= 2, prec ++); 48 49 /* MAXIMUM needs prec bits, i.e. MAXIMUM = 2^prec - 1 */ 50 51 /* if e <= prec - 1, then f < 2^(prec-1) < MAXIMUM */ 52 if (e <= prec - 1) 53 return 1; 54 55 /* if e >= prec + 1, then f >= 2^prec > MAXIMUM */ 56 if (e >= prec + 1) 57 return 0; 58 59 MPFR_ASSERTD (e == prec); 60 61 /* hard case: first round to prec bits, then check */ 62 mpfr_init2 (x, prec); 63 mpfr_set (x, f, rnd); 64 res = MPFR_GET_EXP (x) == e; 65 mpfr_clear (x); 66 return res; 67} 68