1 | /* Test for NaN that does not need libm. |
2 | Copyright (C) 2007-2013 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 |
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 | |