1 /* Test for NaN that does not need libm.
2 Copyright (C) 2007-2011 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. */
22 #ifdef USE_LONG_DOUBLE
23 /* Specification found in math.h or isnanl-nolibm.h. */
24 extern int rpl_isnanl (long double x);
25 #elif ! defined USE_FLOAT
26 /* Specification found in math.h or isnand-nolibm.h. */
27 extern int rpl_isnand (double x);
28 #else /* defined USE_FLOAT */
29 /* Specification found in math.h or isnanf-nolibm.h. */
30 extern int rpl_isnanf (float x);
38 #ifdef USE_LONG_DOUBLE
39 # define FUNC rpl_isnanl
40 # define DOUBLE long double
41 # define MAX_EXP LDBL_MAX_EXP
42 # define MIN_EXP LDBL_MIN_EXP
43 # if defined LDBL_EXPBIT0_WORD && defined LDBL_EXPBIT0_BIT
44 # define KNOWN_EXPBIT0_LOCATION
45 # define EXPBIT0_WORD LDBL_EXPBIT0_WORD
46 # define EXPBIT0_BIT LDBL_EXPBIT0_BIT
48 # define SIZE SIZEOF_LDBL
49 # define L_(literal) literal##L
50 #elif ! defined USE_FLOAT
51 # define FUNC rpl_isnand
52 # define DOUBLE double
53 # define MAX_EXP DBL_MAX_EXP
54 # define MIN_EXP DBL_MIN_EXP
55 # if defined DBL_EXPBIT0_WORD && defined DBL_EXPBIT0_BIT
56 # define KNOWN_EXPBIT0_LOCATION
57 # define EXPBIT0_WORD DBL_EXPBIT0_WORD
58 # define EXPBIT0_BIT DBL_EXPBIT0_BIT
60 # define SIZE SIZEOF_DBL
61 # define L_(literal) literal
62 #else /* defined USE_FLOAT */
63 # define FUNC rpl_isnanf
65 # define MAX_EXP FLT_MAX_EXP
66 # define MIN_EXP FLT_MIN_EXP
67 # if defined FLT_EXPBIT0_WORD && defined FLT_EXPBIT0_BIT
68 # define KNOWN_EXPBIT0_LOCATION
69 # define EXPBIT0_WORD FLT_EXPBIT0_WORD
70 # define EXPBIT0_BIT FLT_EXPBIT0_BIT
72 # define SIZE SIZEOF_FLT
73 # define L_(literal) literal##f
76 #define EXP_MASK ((MAX_EXP - MIN_EXP) | 7)
79 ((sizeof (DOUBLE) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
80 typedef union { DOUBLE value; unsigned int word[NWORDS]; } memory_double;
82 /* The attribute __const__ was added in gcc 2.95. */
83 #undef _GL_ATTRIBUTE_CONST
84 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 95)
85 # define _GL_ATTRIBUTE_CONST __attribute__ ((__const__))
87 # define _GL_ATTRIBUTE_CONST /* empty */
90 int _GL_ATTRIBUTE_CONST
93 #ifdef KNOWN_EXPBIT0_LOCATION
94 # 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_))
95 /* Special CPU dependent code is needed to treat bit patterns outside the
96 IEEE 754 specification (such as Pseudo-NaNs, Pseudo-Infinities,
97 Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals) as NaNs.
98 These bit patterns are:
99 - exponent = 0x0001..0x7FFF, mantissa bit 63 = 0,
100 - exponent = 0x0000, mantissa bit 63 = 1.
101 The NaN bit pattern is:
102 - exponent = 0x7FFF, mantissa >= 0x8000000000000001. */
104 unsigned int exponent;
107 exponent = (m.word[EXPBIT0_WORD] >> EXPBIT0_BIT) & EXP_MASK;
108 # ifdef WORDS_BIGENDIAN
109 /* Big endian: EXPBIT0_WORD = 0, EXPBIT0_BIT = 16. */
111 return 1 & (m.word[0] >> 15);
112 else if (exponent == EXP_MASK)
113 return (((m.word[0] ^ 0x8000U) << 16) | m.word[1] | (m.word[2] >> 16)) != 0;
115 return 1 & ~(m.word[0] >> 15);
117 /* Little endian: EXPBIT0_WORD = 2, EXPBIT0_BIT = 0. */
119 return (m.word[1] >> 31);
120 else if (exponent == EXP_MASK)
121 return ((m.word[1] ^ 0x80000000U) | m.word[0]) != 0;
123 return (m.word[1] >> 31) ^ 1;
126 /* Be careful to not do any floating-point operation on x, such as x == x,
127 because x may be a signaling NaN. */
128 # if defined __TINYC__ || defined __SUNPRO_C || defined __DECC \
129 || (defined __sgi && !defined __GNUC__) || defined __ICC
130 /* The Sun C 5.0, Intel ICC 10.0, and Compaq (ex-DEC) 6.4 compilers don't
131 recognize the initializers as constant expressions. The latter compiler
132 also fails when constant-folding 0.0 / 0.0 even when constant-folding is
133 not required. The SGI MIPSpro C compiler complains about "floating-point
134 operation result is out of range". */
135 static DOUBLE zero = L_(0.0);
137 DOUBLE plus_inf = L_(1.0) / L_(0.0);
138 DOUBLE minus_inf = -L_(1.0) / L_(0.0);
139 nan.value = zero / zero;
141 static memory_double nan = { L_(0.0) / L_(0.0) };
142 static DOUBLE plus_inf = L_(1.0) / L_(0.0);
143 static DOUBLE minus_inf = -L_(1.0) / L_(0.0);
148 /* A NaN can be recognized through its exponent. But exclude +Infinity and
149 -Infinity, which have the same exponent. */
151 if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD])
152 & (EXP_MASK << EXPBIT0_BIT))
154 return (memcmp (&m.value, &plus_inf, SIZE) != 0
155 && memcmp (&m.value, &minus_inf, SIZE) != 0);
161 /* The configuration did not find sufficient information. Give up about
162 the signaling NaNs, handle only the quiet NaNs. */
165 # 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_))
166 /* Detect any special bit patterns that pass ==; see comment above. */
170 memset (&m1.value, 0, SIZE);
171 memset (&m2.value, 0, SIZE);
173 m2.value = x + (x ? 0.0L : -0.0L);
174 if (memcmp (&m1.value, &m2.value, SIZE) != 0)