1 /* mpfr_cmp_si_2exp -- compare a floating-point number with a signed
2 machine integer multiplied by a power of 2
4 Copyright 1999, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
5 Contributed by the Arenaire and Caramel projects, INRIA.
7 This file is part of the GNU MPFR Library.
9 The GNU MPFR Library is free software; you can redistribute it and/or modify
10 it under the terms of the GNU Lesser General Public License as published by
11 the Free Software Foundation; either version 3 of the License, or (at your
12 option) any later version.
14 The GNU MPFR Library is distributed in the hope that it will be useful, but
15 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
16 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
17 License for more details.
19 You should have received a copy of the GNU Lesser General Public License
20 along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
21 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
22 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
24 #define MPFR_NEED_LONGLONG_H
25 #include "mpfr-impl.h"
27 /* returns a positive value if b > i*2^f,
28 a negative value if b < i*2^f,
34 mpfr_cmp_si_2exp (mpfr_srcptr b, long int i, mpfr_exp_t f)
38 si = i < 0 ? -1 : 1; /* sign of i */
39 if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (b)))
42 return MPFR_INT_SIGN(b);
43 else if (MPFR_IS_ZERO(b))
44 return i != 0 ? -si : 0;
49 else if (MPFR_SIGN(b) != si || i == 0)
50 return MPFR_INT_SIGN (b);
51 else /* b and i are of same sign si */
59 ai = SAFE_ABS(unsigned long, i);
61 /* ai must be representable in a mp_limb_t */
62 MPFR_ASSERTN(ai == (mp_limb_t) ai);
64 e = MPFR_GET_EXP (b); /* 2^(e-1) <= b < 2^e */
67 if (f < MPFR_EMAX_MAX - GMP_NUMB_BITS &&
68 e > f + GMP_NUMB_BITS)
71 /* now f < e <= f + GMP_NUMB_BITS */
73 count_leading_zeros(k, c);
74 if ((int) (e - f) > GMP_NUMB_BITS - k)
76 if ((int) (e - f) < GMP_NUMB_BITS - k)
79 /* now b and i*2^f have the same exponent */
81 bn = (MPFR_PREC(b) - 1) / GMP_NUMB_BITS;
88 /* most significant limbs agree, check remaining limbs from b */
98 mpfr_cmp_si (mpfr_srcptr b, long int i)
100 return mpfr_cmp_si_2exp (b, i, 0);