| /* mpfr_get_ui -- convert a floating-point number to an unsigned long. |
| |
| Copyright 2003, 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. */ |
| |
| #include "mpfr-impl.h" |
| |
| unsigned long |
| mpfr_get_ui (mpfr_srcptr f, mp_rnd_t rnd) |
| { |
| mp_prec_t prec; |
| unsigned long s; |
| mpfr_t x; |
| mp_size_t n; |
| mp_exp_t exp; |
| |
| if (!mpfr_fits_ulong_p (f, rnd)) |
| { |
| MPFR_SET_ERANGE (); |
| return MPFR_IS_NEG (f) ? 0 : ULONG_MAX; |
| } |
| |
| if (MPFR_IS_ZERO (f)) |
| return (unsigned long) 0; |
| |
| for (s = ULONG_MAX, prec = 0; s != 0; s >>= 1, prec ++); |
| |
| /* first round to prec bits */ |
| mpfr_init2 (x, prec); |
| mpfr_rint (x, f, rnd); |
| |
| /* warning: if x=0, taking its exponent is illegal */ |
| if (MPFR_IS_ZERO(x)) |
| s = 0; |
| else |
| { |
| /* now the result is in the most significant limb of x */ |
| exp = MPFR_GET_EXP (x); /* since |x| >= 1, exp >= 1 */ |
| n = MPFR_LIMB_SIZE(x); |
| s = MPFR_MANT(x)[n - 1] >> (BITS_PER_MP_LIMB - exp); |
| } |
| |
| mpfr_clear (x); |
| |
| return s; |
| } |