1 /* mpfr_fits_*_p -- test whether an mpfr fits a C signed type.
3 Copyright 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
4 Contributed by the Arenaire and Caramel projects, INRIA.
6 This file is part of the GNU MPFR Library.
8 The GNU MPFR Library is free software; you can redistribute it and/or modify
9 it under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 3 of the License, or (at your
11 option) any later version.
13 The GNU MPFR Library is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
16 License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
20 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
23 #include "mpfr-impl.h"
25 /* The original version of this file came from GMP's mpf/fits_s.h;
26 it has been adapted for MPFR. In particular, the result can be
27 rounded away from zero. */
30 FUNCTION (mpfr_srcptr f, mpfr_rnd_t rnd)
38 if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (f)))
40 return MPFR_IS_ZERO (f) ? 1 : 0;
42 /* now it fits if either
43 (a) MINIMUM <= f <= MAXIMUM
44 (b) or MINIMUM <= round(f, prec(slong), rnd) <= MAXIMUM */
48 return 1; /* |f| < 1: always fits */
50 neg = MPFR_IS_NEG (f);
52 /* let EXTREMUM be MAXIMUM if f > 0, and MINIMUM if f < 0 */
54 /* first compute prec(EXTREMUM), this could be done at configure time,
55 but the result can depend on neg (the loop is moved inside the "if"
56 to give the compiler a better chance to compute prec statically) */
60 /* In C89, the division on negative integers isn't well-defined. */
61 s = SAFE_ABS (unsigned TYPE, MINIMUM);
62 for (prec = 0; s != 0; s /= 2, prec ++);
68 for (prec = 0; s != 0; s /= 2, prec ++);
71 /* EXTREMUM needs prec bits, i.e. 2^(prec-1) <= |EXTREMUM| < 2^prec */
73 /* if e <= prec - 1, then f < 2^(prec-1) <= |EXTREMUM| */
77 /* if e >= prec + 1, then f >= 2^prec > |EXTREMUM| */
81 MPFR_ASSERTD (e == prec);
83 /* hard case: first round to prec bits, then check */
86 res = neg ? (mpfr_cmp_si (x, MINIMUM) >= 0) : (MPFR_GET_EXP (x) == e);