1/* mpfr_cmpabs -- compare the absolute values of two FP numbers
2
3Copyright 1999, 2001, 2002, 2003, 2004, 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
25/* Return a positive value if abs(b) > abs(c), 0 if abs(b) = abs(c), and
26   a negative value if abs(b) < abs(c). Neither b nor c may be NaN. */
27
28int
29mpfr_cmpabs (mpfr_srcptr b, mpfr_srcptr c)
30{
31  mpfr_exp_t be, ce;
32  mp_size_t bn, cn;
33  mp_limb_t *bp, *cp;
34
35  if (MPFR_ARE_SINGULAR (b, c))
36    {
37      if (MPFR_IS_NAN (b) || MPFR_IS_NAN (c))
38        {
39          MPFR_SET_ERANGE ();
40          return 0;
41        }
42      else if (MPFR_IS_INF (b))
43        return ! MPFR_IS_INF (c);
44      else if (MPFR_IS_INF (c))
45        return -1;
46      else if (MPFR_IS_ZERO (c))
47        return ! MPFR_IS_ZERO (b);
48      else /* b == 0 */
49        return -1;
50    }
51
52  MPFR_ASSERTD (MPFR_IS_PURE_FP (b));
53  MPFR_ASSERTD (MPFR_IS_PURE_FP (c));
54
55  /* Now that we know that b and c are pure FP numbers (i.e. they have
56     a meaningful exponent), we use MPFR_EXP instead of MPFR_GET_EXP to
57     allow exponents outside the current exponent range. For instance,
58     this is useful for mpfr_pow, which compares values to __gmpfr_one.
59     This is for internal use only! For compatibility with other MPFR
60     versions, the user must still provide values that are representable
61     in the current exponent range. */
62  be = MPFR_EXP (b);
63  ce = MPFR_EXP (c);
64  if (be > ce)
65    return 1;
66  if (be < ce)
67    return -1;
68
69  /* exponents are equal */
70
71  bn = MPFR_LIMB_SIZE(b)-1;
72  cn = MPFR_LIMB_SIZE(c)-1;
73
74  bp = MPFR_MANT(b);
75  cp = MPFR_MANT(c);
76
77  for ( ; bn >= 0 && cn >= 0; bn--, cn--)
78    {
79      if (bp[bn] > cp[cn])
80        return 1;
81      if (bp[bn] < cp[cn])
82        return -1;
83    }
84
85  for ( ; bn >= 0; bn--)
86    if (bp[bn])
87      return 1;
88
89  for ( ; cn >= 0; cn--)
90    if (cp[cn])
91      return -1;
92
93   return 0;
94}
95