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| 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 |
| 83 FUNC (DOUBLE x) |
| 84 { |
| 85 #ifdef KNOWN_EXPBIT0_LOCATION |
| 86 # if defined USE_LONG_DOUBLE && ((defined __ia64 && LDBL_MANT_DIG == 64) || (def
ined __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) || (def
ined __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 } |
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