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88b48903 | 1 | /* Test for NaN that does not need libm. |
5df4cba6 | 2 | Copyright (C) 2007-2020 Free Software Foundation, Inc. |
88b48903 WN |
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 | |
c0c3707f | 15 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
88b48903 WN |
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 | ||
4a626d0a PA |
82 | /* Most hosts nowadays use IEEE floating point, so they use IEC 60559 |
83 | representations, have infinities and NaNs, and do not trap on | |
84 | exceptions. Define IEEE_FLOATING_POINT if this host is one of the | |
85 | typical ones. The C11 macro __STDC_IEC_559__ is close to what is | |
86 | wanted here, but is not quite right because this file does not require | |
87 | all the features of C11 Annex F (and does not require C11 at all, | |
88 | for that matter). */ | |
89 | ||
90 | #define IEEE_FLOATING_POINT (FLT_RADIX == 2 && FLT_MANT_DIG == 24 \ | |
91 | && FLT_MIN_EXP == -125 && FLT_MAX_EXP == 128) | |
92 | ||
88b48903 WN |
93 | int |
94 | FUNC (DOUBLE x) | |
95 | { | |
4a626d0a | 96 | #if defined KNOWN_EXPBIT0_LOCATION && IEEE_FLOATING_POINT |
88b48903 WN |
97 | # 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 |
98 | /* Special CPU dependent code is needed to treat bit patterns outside the | |
99 | IEEE 754 specification (such as Pseudo-NaNs, Pseudo-Infinities, | |
100 | Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals) as NaNs. | |
101 | These bit patterns are: | |
102 | - exponent = 0x0001..0x7FFF, mantissa bit 63 = 0, | |
103 | - exponent = 0x0000, mantissa bit 63 = 1. | |
104 | The NaN bit pattern is: | |
105 | - exponent = 0x7FFF, mantissa >= 0x8000000000000001. */ | |
106 | memory_double m; | |
107 | unsigned int exponent; | |
108 | ||
109 | m.value = x; | |
110 | exponent = (m.word[EXPBIT0_WORD] >> EXPBIT0_BIT) & EXP_MASK; | |
111 | # ifdef WORDS_BIGENDIAN | |
112 | /* Big endian: EXPBIT0_WORD = 0, EXPBIT0_BIT = 16. */ | |
113 | if (exponent == 0) | |
114 | return 1 & (m.word[0] >> 15); | |
115 | else if (exponent == EXP_MASK) | |
116 | return (((m.word[0] ^ 0x8000U) << 16) | m.word[1] | (m.word[2] >> 16)) != 0; | |
117 | else | |
118 | return 1 & ~(m.word[0] >> 15); | |
119 | # else | |
120 | /* Little endian: EXPBIT0_WORD = 2, EXPBIT0_BIT = 0. */ | |
121 | if (exponent == 0) | |
122 | return (m.word[1] >> 31); | |
123 | else if (exponent == EXP_MASK) | |
124 | return ((m.word[1] ^ 0x80000000U) | m.word[0]) != 0; | |
125 | else | |
126 | return (m.word[1] >> 31) ^ 1; | |
127 | # endif | |
128 | # else | |
129 | /* Be careful to not do any floating-point operation on x, such as x == x, | |
130 | because x may be a signaling NaN. */ | |
131 | # if defined __SUNPRO_C || defined __ICC || defined _MSC_VER \ | |
132 | || defined __DECC || defined __TINYC__ \ | |
133 | || (defined __sgi && !defined __GNUC__) | |
134 | /* The Sun C 5.0, Intel ICC 10.0, Microsoft Visual C/C++ 9.0, Compaq (ex-DEC) | |
135 | 6.4, and TinyCC compilers don't recognize the initializers as constant | |
136 | expressions. The Compaq compiler also fails when constant-folding | |
137 | 0.0 / 0.0 even when constant-folding is not required. The Microsoft | |
138 | Visual C/C++ compiler also fails when constant-folding 1.0 / 0.0 even | |
139 | when constant-folding is not required. The SGI MIPSpro C compiler | |
140 | complains about "floating-point operation result is out of range". */ | |
141 | static DOUBLE zero = L_(0.0); | |
142 | memory_double nan; | |
143 | DOUBLE plus_inf = L_(1.0) / zero; | |
144 | DOUBLE minus_inf = -L_(1.0) / zero; | |
145 | nan.value = zero / zero; | |
146 | # else | |
147 | static memory_double nan = { L_(0.0) / L_(0.0) }; | |
148 | static DOUBLE plus_inf = L_(1.0) / L_(0.0); | |
149 | static DOUBLE minus_inf = -L_(1.0) / L_(0.0); | |
150 | # endif | |
151 | { | |
152 | memory_double m; | |
153 | ||
154 | /* A NaN can be recognized through its exponent. But exclude +Infinity and | |
155 | -Infinity, which have the same exponent. */ | |
156 | m.value = x; | |
157 | if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD]) | |
158 | & (EXP_MASK << EXPBIT0_BIT)) | |
159 | == 0) | |
160 | return (memcmp (&m.value, &plus_inf, SIZE) != 0 | |
161 | && memcmp (&m.value, &minus_inf, SIZE) != 0); | |
162 | else | |
163 | return 0; | |
164 | } | |
165 | # endif | |
166 | #else | |
4a626d0a PA |
167 | /* The configuration did not find sufficient information, or does |
168 | not use IEEE floating point. Give up about the signaling NaNs; | |
169 | handle only the quiet NaNs. */ | |
88b48903 WN |
170 | if (x == x) |
171 | { | |
172 | # 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 | |
173 | /* Detect any special bit patterns that pass ==; see comment above. */ | |
174 | memory_double m1; | |
175 | memory_double m2; | |
176 | ||
177 | memset (&m1.value, 0, SIZE); | |
178 | memset (&m2.value, 0, SIZE); | |
179 | m1.value = x; | |
180 | m2.value = x + (x ? 0.0L : -0.0L); | |
181 | if (memcmp (&m1.value, &m2.value, SIZE) != 0) | |
182 | return 1; | |
183 | # endif | |
184 | return 0; | |
185 | } | |
186 | else | |
187 | return 1; | |
188 | #endif | |
189 | } |