1 /* Test for NaN that does not need libm.
2 Copyright (C) 2007-2008 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 3 of the License, or
7 (at your option) any later version.
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
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17 /* Written by Bruno Haible <bruno@clisp.org>, 2007. */
26 #ifdef USE_LONG_DOUBLE
27 # define FUNC rpl_isnanl
28 # define DOUBLE long double
29 # define MAX_EXP LDBL_MAX_EXP
30 # define MIN_EXP LDBL_MIN_EXP
31 # if defined LDBL_EXPBIT0_WORD && defined LDBL_EXPBIT0_BIT
32 # define KNOWN_EXPBIT0_LOCATION
33 # define EXPBIT0_WORD LDBL_EXPBIT0_WORD
34 # define EXPBIT0_BIT LDBL_EXPBIT0_BIT
36 # define SIZE SIZEOF_LDBL
37 # define L_(literal) literal##L
38 #elif ! defined USE_FLOAT
39 # define FUNC rpl_isnand
40 # define DOUBLE double
41 # define MAX_EXP DBL_MAX_EXP
42 # define MIN_EXP DBL_MIN_EXP
43 # if defined DBL_EXPBIT0_WORD && defined DBL_EXPBIT0_BIT
44 # define KNOWN_EXPBIT0_LOCATION
45 # define EXPBIT0_WORD DBL_EXPBIT0_WORD
46 # define EXPBIT0_BIT DBL_EXPBIT0_BIT
48 # define SIZE SIZEOF_DBL
49 # define L_(literal) literal
50 #else /* defined USE_FLOAT */
51 # define FUNC rpl_isnanf
53 # define MAX_EXP FLT_MAX_EXP
54 # define MIN_EXP FLT_MIN_EXP
55 # if defined FLT_EXPBIT0_WORD && defined FLT_EXPBIT0_BIT
56 # define KNOWN_EXPBIT0_LOCATION
57 # define EXPBIT0_WORD FLT_EXPBIT0_WORD
58 # define EXPBIT0_BIT FLT_EXPBIT0_BIT
60 # define SIZE SIZEOF_FLT
61 # define L_(literal) literal##f
64 #define EXP_MASK ((MAX_EXP - MIN_EXP) | 7)
67 ((sizeof (DOUBLE) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
68 typedef union { DOUBLE value; unsigned int word[NWORDS]; } memory_double;
73 #ifdef KNOWN_EXPBIT0_LOCATION
74 # if defined USE_LONG_DOUBLE && ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_))
75 /* Special CPU dependent code is needed to treat bit patterns outside the
76 IEEE 754 specification (such as Pseudo-NaNs, Pseudo-Infinities,
77 Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals) as NaNs.
78 These bit patterns are:
79 - exponent = 0x0001..0x7FFF, mantissa bit 63 = 0,
80 - exponent = 0x0000, mantissa bit 63 = 1.
81 The NaN bit pattern is:
82 - exponent = 0x7FFF, mantissa >= 0x8000000000000001. */
84 unsigned int exponent;
87 exponent = (m.word[EXPBIT0_WORD] >> EXPBIT0_BIT) & EXP_MASK;
88 # ifdef WORDS_BIGENDIAN
89 /* Big endian: EXPBIT0_WORD = 0, EXPBIT0_BIT = 16. */
91 return 1 & (m.word[0] >> 15);
92 else if (exponent == EXP_MASK)
93 return (((m.word[0] ^ 0x8000U) << 16) | m.word[1] | (m.word[2] >> 16)) != 0;
95 return 1 & ~(m.word[0] >> 15);
97 /* Little endian: EXPBIT0_WORD = 2, EXPBIT0_BIT = 0. */
99 return (m.word[1] >> 31);
100 else if (exponent == EXP_MASK)
101 return ((m.word[1] ^ 0x80000000U) | m.word[0]) != 0;
103 return (m.word[1] >> 31) ^ 1;
106 /* Be careful to not do any floating-point operation on x, such as x == x,
107 because x may be a signaling NaN. */
108 # if defined __SUNPRO_C || defined __DECC || (defined __sgi && !defined __GNUC__)
109 /* The Sun C 5.0 compilers and the Compaq (ex-DEC) 6.4 compilers don't
110 recognize the initializers as constant expressions. The latter compiler
111 also fails when constant-folding 0.0 / 0.0 even when constant-folding is
112 not required. The SGI MIPSpro C compiler complains about "floating-point
113 operation result is out of range". */
114 static DOUBLE zero = L_(0.0);
116 DOUBLE plus_inf = L_(1.0) / L_(0.0);
117 DOUBLE minus_inf = -L_(1.0) / L_(0.0);
118 nan.value = zero / zero;
120 static memory_double nan = { L_(0.0) / L_(0.0) };
121 static DOUBLE plus_inf = L_(1.0) / L_(0.0);
122 static DOUBLE minus_inf = -L_(1.0) / L_(0.0);
127 /* A NaN can be recognized through its exponent. But exclude +Infinity and
128 -Infinity, which have the same exponent. */
130 if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD])
131 & (EXP_MASK << EXPBIT0_BIT))
133 return (memcmp (&m.value, &plus_inf, SIZE) != 0
134 && memcmp (&m.value, &minus_inf, SIZE) != 0);
140 /* The configuration did not find sufficient information. Give up about
141 the signaling NaNs, handle only the quiet NaNs. */
144 # if defined USE_LONG_DOUBLE && ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_))
145 /* Detect any special bit patterns that pass ==; see comment above. */
149 memset (&m1.value, 0, SIZE);
150 memset (&m2.value, 0, SIZE);
152 m2.value = x + (x ? 0.0L : -0.0L);
153 if (memcmp (&m1.value, &m2.value, SIZE) != 0)