1 /* Test for NaN that does not need libm.
2 Copyright (C) 2007-2012 Free Software Foundation, Inc.
3
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.
8
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.
13
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/>. */
16
17 /* Written by Bruno Haible <bruno@clisp.org>, 2007. */
18
19 #include <config.h>
20
21 /* Specification. */
22 #ifdef USE_LONG_DOUBLE
23 /* Specification found in math.h or isnanl-nolibm.h. */
24 extern int rpl_isnanl (long double x) _GL_ATTRIBUTE_CONST;
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);
31 #endif
32
33 #include <float.h>
34 #include <string.h>
35
36 #include "float+.h"
37
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
47 # endif
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
59 # endif
60 # define SIZE SIZEOF_DBL
61 # define L_(literal) literal
62 #else /* defined USE_FLOAT */
63 # define FUNC rpl_isnanf
64 # define DOUBLE float
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
71 # endif
72 # define SIZE SIZEOF_FLT
73 # define L_(literal) literal##f
74 #endif
75
76 #define EXP_MASK ((MAX_EXP - MIN_EXP) | 7)
77
78 #define NWORDS \
79 ((sizeof (DOUBLE) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
80 typedef union { DOUBLE value; unsigned int word[NWORDS]; } memory_double;
81
82 int
FUNC(DOUBLE x)83 FUNC (DOUBLE x)
84 {
85 #ifdef KNOWN_EXPBIT0_LOCATION
86 # 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_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
87 /* Special CPU dependent code is needed to treat bit patterns outside the
88 IEEE 754 specification (such as Pseudo-NaNs, Pseudo-Infinities,
89 Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals) as NaNs.
90 These bit patterns are:
91 - exponent = 0x0001..0x7FFF, mantissa bit 63 = 0,
92 - exponent = 0x0000, mantissa bit 63 = 1.
93 The NaN bit pattern is:
94 - exponent = 0x7FFF, mantissa >= 0x8000000000000001. */
95 memory_double m;
96 unsigned int exponent;
97
98 m.value = x;
99 exponent = (m.word[EXPBIT0_WORD] >> EXPBIT0_BIT) & EXP_MASK;
100 # ifdef WORDS_BIGENDIAN
101 /* Big endian: EXPBIT0_WORD = 0, EXPBIT0_BIT = 16. */
102 if (exponent == 0)
103 return 1 & (m.word[0] >> 15);
104 else if (exponent == EXP_MASK)
105 return (((m.word[0] ^ 0x8000U) << 16) | m.word[1] | (m.word[2] >> 16)) != 0;
106 else
107 return 1 & ~(m.word[0] >> 15);
108 # else
109 /* Little endian: EXPBIT0_WORD = 2, EXPBIT0_BIT = 0. */
110 if (exponent == 0)
111 return (m.word[1] >> 31);
112 else if (exponent == EXP_MASK)
113 return ((m.word[1] ^ 0x80000000U) | m.word[0]) != 0;
114 else
115 return (m.word[1] >> 31) ^ 1;
116 # endif
117 # else
118 /* Be careful to not do any floating-point operation on x, such as x == x,
119 because x may be a signaling NaN. */
120 # if defined __SUNPRO_C || defined __ICC || defined _MSC_VER \
121 || defined __DECC || defined __TINYC__ \
122 || (defined __sgi && !defined __GNUC__)
123 /* The Sun C 5.0, Intel ICC 10.0, Microsoft Visual C/C++ 9.0, Compaq (ex-DEC)
124 6.4, and TinyCC compilers don't recognize the initializers as constant
125 expressions. The Compaq compiler also fails when constant-folding
126 0.0 / 0.0 even when constant-folding is not required. The Microsoft
127 Visual C/C++ compiler also fails when constant-folding 1.0 / 0.0 even
128 when constant-folding is not required. The SGI MIPSpro C compiler
129 complains about "floating-point operation result is out of range". */
130 static DOUBLE zero = L_(0.0);
131 memory_double nan;
132 DOUBLE plus_inf = L_(1.0) / zero;
133 DOUBLE minus_inf = -L_(1.0) / zero;
134 nan.value = zero / zero;
135 # else
136 static memory_double nan = { L_(0.0) / L_(0.0) };
137 static DOUBLE plus_inf = L_(1.0) / L_(0.0);
138 static DOUBLE minus_inf = -L_(1.0) / L_(0.0);
139 # endif
140 {
141 memory_double m;
142
143 /* A NaN can be recognized through its exponent. But exclude +Infinity and
144 -Infinity, which have the same exponent. */
145 m.value = x;
146 if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD])
147 & (EXP_MASK << EXPBIT0_BIT))
148 == 0)
149 return (memcmp (&m.value, &plus_inf, SIZE) != 0
150 && memcmp (&m.value, &minus_inf, SIZE) != 0);
151 else
152 return 0;
153 }
154 # endif
155 #else
156 /* The configuration did not find sufficient information. Give up about
157 the signaling NaNs, handle only the quiet NaNs. */
158 if (x == x)
159 {
160 # 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_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
161 /* Detect any special bit patterns that pass ==; see comment above. */
162 memory_double m1;
163 memory_double m2;
164
165 memset (&m1.value, 0, SIZE);
166 memset (&m2.value, 0, SIZE);
167 m1.value = x;
168 m2.value = x + (x ? 0.0L : -0.0L);
169 if (memcmp (&m1.value, &m2.value, SIZE) != 0)
170 return 1;
171 # endif
172 return 0;
173 }
174 else
175 return 1;
176 #endif
177 }
178