1 /* Test for NaN that does not need libm.
2 Copyright (C) 2007 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 2, or (at your option)
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License along
15 with this program; if not, write to the Free Software Foundation,
16 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
18 /* Written by Bruno Haible <bruno@clisp.org>, 2007. */
27 #ifdef USE_LONG_DOUBLE
28 # define FUNC rpl_isnanl
29 # define DOUBLE long double
30 # define MAX_EXP LDBL_MAX_EXP
31 # define MIN_EXP LDBL_MIN_EXP
32 # if defined LDBL_EXPBIT0_WORD && defined LDBL_EXPBIT0_BIT
33 # define KNOWN_EXPBIT0_LOCATION
34 # define EXPBIT0_WORD LDBL_EXPBIT0_WORD
35 # define EXPBIT0_BIT LDBL_EXPBIT0_BIT
37 # define SIZE SIZEOF_LDBL
38 # define L_(literal) literal##L
39 #elif ! defined USE_FLOAT
40 # define FUNC rpl_isnan
41 # define DOUBLE double
42 # define MAX_EXP DBL_MAX_EXP
43 # define MIN_EXP DBL_MIN_EXP
44 # if defined DBL_EXPBIT0_WORD && defined DBL_EXPBIT0_BIT
45 # define KNOWN_EXPBIT0_LOCATION
46 # define EXPBIT0_WORD DBL_EXPBIT0_WORD
47 # define EXPBIT0_BIT DBL_EXPBIT0_BIT
49 # define SIZE SIZEOF_DBL
50 # define L_(literal) literal
51 #else /* defined USE_FLOAT */
52 # define FUNC rpl_isnanf
54 # define MAX_EXP FLT_MAX_EXP
55 # define MIN_EXP FLT_MIN_EXP
56 # if defined FLT_EXPBIT0_WORD && defined FLT_EXPBIT0_BIT
57 # define KNOWN_EXPBIT0_LOCATION
58 # define EXPBIT0_WORD FLT_EXPBIT0_WORD
59 # define EXPBIT0_BIT FLT_EXPBIT0_BIT
61 # define SIZE SIZEOF_FLT
62 # define L_(literal) literal##f
65 #define EXP_MASK ((MAX_EXP - MIN_EXP) | 7)
68 ((sizeof (DOUBLE) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
69 typedef union { DOUBLE value; unsigned int word[NWORDS]; } memory_double;
74 #ifdef KNOWN_EXPBIT0_LOCATION
75 /* Be careful to not do any floating-point operation on x, such as x == x,
76 because x may be a signaling NaN. */
77 # if defined __SUNPRO_C || defined __DECC
78 /* The Sun C 5.0 compilers and the Compaq (ex-DEC) 6.4 compilers don't
79 recognize the initializers as constant expressions. The latter compiler
80 also fails when constant-folding 0.0 / 0.0 even when constant-folding is
82 static DOUBLE zero = L_(0.0);
84 DOUBLE plus_inf = L_(1.0) / L_(0.0);
85 DOUBLE minus_inf = -L_(1.0) / L_(0.0);
86 nan.value = zero / zero;
88 static memory_double nan = { L_(0.0) / L_(0.0) };
89 static DOUBLE plus_inf = L_(1.0) / L_(0.0);
90 static DOUBLE minus_inf = -L_(1.0) / L_(0.0);
95 /* A NaN can be recognized through its exponent. But exclude +Infinity and
96 -Infinity, which have the same exponent. */
98 if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD])
99 & (EXP_MASK << EXPBIT0_BIT))
101 return (memcmp (&m.value, &plus_inf, SIZE) != 0
102 && memcmp (&m.value, &minus_inf, SIZE) != 0);
107 /* The configuration did not find sufficient information. Give up about
108 the signaling NaNs, handle only the quiet NaNs. */