1/* mpfr_cmp -- compare two floating-point numbers
2
3Copyright 1999, 2001, 2003, 2004, 2005, 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/* returns 0 iff b = sign(s) * c
26           a positive value iff b > sign(s) * c
27           a negative value iff b < sign(s) * c
28   returns 0 and sets erange flag if b and/or c is NaN.
29*/
30
31int
32mpfr_cmp3 (mpfr_srcptr b, mpfr_srcptr c, int s)
33{
34  mpfr_exp_t be, ce;
35  mp_size_t bn, cn;
36  mp_limb_t *bp, *cp;
37
38  s = MPFR_MULT_SIGN( s , MPFR_SIGN(c) );
39
40  if (MPFR_ARE_SINGULAR(b, c))
41    {
42      if (MPFR_IS_NAN (b) || MPFR_IS_NAN (c))
43        {
44          MPFR_SET_ERANGE ();
45          return 0;
46        }
47      else if (MPFR_IS_INF(b))
48        {
49          if (MPFR_IS_INF(c) && s == MPFR_SIGN(b) )
50            return 0;
51          else
52            return MPFR_SIGN(b);
53        }
54      else if (MPFR_IS_INF(c))
55        return -s;
56      else if (MPFR_IS_ZERO(b))
57        return MPFR_IS_ZERO(c) ? 0 : -s;
58      else /* necessarily c=0 */
59        return MPFR_SIGN(b);
60    }
61  /* b and c are real numbers */
62  if (s != MPFR_SIGN(b))
63    return MPFR_SIGN(b);
64
65  /* now signs are equal */
66
67  be = MPFR_GET_EXP (b);
68  ce = MPFR_GET_EXP (c);
69  if (be > ce)
70    return s;
71  if (be < ce)
72    return -s;
73
74  /* both signs and exponents are equal */
75
76  bn = (MPFR_PREC(b)-1)/GMP_NUMB_BITS;
77  cn = (MPFR_PREC(c)-1)/GMP_NUMB_BITS;
78
79  bp = MPFR_MANT(b);
80  cp = MPFR_MANT(c);
81
82  for ( ; bn >= 0 && cn >= 0; bn--, cn--)
83    {
84      if (bp[bn] > cp[cn])
85        return s;
86      if (bp[bn] < cp[cn])
87        return -s;
88    }
89  for ( ; bn >= 0; bn--)
90    if (bp[bn])
91      return s;
92  for ( ; cn >= 0; cn--)
93    if (cp[cn])
94      return -s;
95
96   return 0;
97}
98
99#undef mpfr_cmp
100int
101mpfr_cmp (mpfr_srcptr b, mpfr_srcptr c)
102{
103  return mpfr_cmp3 (b, c, 1);
104}
105