Line data Source code
1 : /* Test for NaN that does not need libm.
2 : Copyright (C) 2007-2008 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 : #include <float.h>
22 : #include <string.h>
23 :
24 : #include "float+.h"
25 :
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
35 : # endif
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
47 : # endif
48 : # define SIZE SIZEOF_DBL
49 : # define L_(literal) literal
50 : #else /* defined USE_FLOAT */
51 : # define FUNC rpl_isnanf
52 : # define DOUBLE float
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
59 : # endif
60 : # define SIZE SIZEOF_FLT
61 : # define L_(literal) literal##f
62 : #endif
63 :
64 : #define EXP_MASK ((MAX_EXP - MIN_EXP) | 7)
65 :
66 : #define NWORDS \
67 : ((sizeof (DOUBLE) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
68 : typedef union { DOUBLE value; unsigned int word[NWORDS]; } memory_double;
69 :
70 : int
71 18 : FUNC (DOUBLE x)
72 : {
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. */
83 : memory_double m;
84 : unsigned int exponent;
85 :
86 18 : m.value = x;
87 18 : exponent = (m.word[EXPBIT0_WORD] >> EXPBIT0_BIT) & EXP_MASK;
88 : # ifdef WORDS_BIGENDIAN
89 : /* Big endian: EXPBIT0_WORD = 0, EXPBIT0_BIT = 16. */
90 : if (exponent == 0)
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;
94 : else
95 : return 1 & ~(m.word[0] >> 15);
96 : # else
97 : /* Little endian: EXPBIT0_WORD = 2, EXPBIT0_BIT = 0. */
98 18 : if (exponent == 0)
99 18 : return (m.word[1] >> 31);
100 0 : else if (exponent == EXP_MASK)
101 0 : return ((m.word[1] ^ 0x80000000U) | m.word[0]) != 0;
102 : else
103 0 : return (m.word[1] >> 31) ^ 1;
104 : # endif
105 : # else
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);
115 : memory_double nan;
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;
119 : # else
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);
123 : # endif
124 : {
125 : memory_double m;
126 :
127 : /* A NaN can be recognized through its exponent. But exclude +Infinity and
128 : -Infinity, which have the same exponent. */
129 : m.value = x;
130 : if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD])
131 : & (EXP_MASK << EXPBIT0_BIT))
132 : == 0)
133 : return (memcmp (&m.value, &plus_inf, SIZE) != 0
134 : && memcmp (&m.value, &minus_inf, SIZE) != 0);
135 : else
136 : return 0;
137 : }
138 : # endif
139 : #else
140 : /* The configuration did not find sufficient information. Give up about
141 : the signaling NaNs, handle only the quiet NaNs. */
142 : if (x == x)
143 : {
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. */
146 : memory_double m1;
147 : memory_double m2;
148 :
149 : memset (&m1.value, 0, SIZE);
150 : memset (&m2.value, 0, SIZE);
151 : m1.value = x;
152 : m2.value = x + (x ? 0.0L : -0.0L);
153 : if (memcmp (&m1.value, &m2.value, SIZE) != 0)
154 : return 1;
155 : # endif
156 : return 0;
157 : }
158 : else
159 : return 1;
160 : #endif
161 : }
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