1/* mpfr_integer_p -- test if a mpfr variable is integer.
2
3Copyright 2001, 2002, 2003, 2004, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
4Contributed by the Arenaire and Cacao 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
24#include "mpfr-impl.h"
25
26int
27mpfr_integer_p (mpfr_srcptr x)
28{
29  mpfr_exp_t expo;
30  mpfr_prec_t prec;
31  mp_size_t xn;
32  mp_limb_t *xp;
33
34  if (MPFR_UNLIKELY( MPFR_IS_SINGULAR(x)))
35    return (MPFR_IS_ZERO(x));
36
37  expo = MPFR_GET_EXP (x);
38  if (expo <= 0)
39    return 0;
40
41  prec = MPFR_PREC(x);
42  if ((mpfr_uexp_t) expo >= (mpfr_uexp_t) prec)
43    return 1;
44
45  /* 0 < expo < prec */
46
47  xn =  (mp_size_t) ((prec - 1) / GMP_NUMB_BITS);  /* index of last limb */
48  xn -= (mp_size_t) (expo / GMP_NUMB_BITS);
49  /* now the index of the last limb containing bits of the fractional part */
50
51  xp = MPFR_MANT(x);
52  MPFR_ASSERTN(xn >= 0);
53  if (xp[xn] << (expo % GMP_NUMB_BITS) != 0)
54    return 0;
55  while (--xn >= 0)
56    if (xp[xn] != 0)
57      return 0;
58  return 1;
59}
60