1 /* Test for NaN that does not need libm. 2 Copyright (C) 2007-2022 Free Software Foundation, Inc. 3 4 This file is free software: you can redistribute it and/or modify 5 it under the terms of the GNU Lesser General Public License as 6 published by the Free Software Foundation; either version 2.1 of the 7 License, or (at your option) any later version. 8 9 This file 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 Lesser General Public License for more details. 13 14 You should have received a copy of the GNU Lesser General Public License 15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ 16 17 /* Written by Bruno Haible <bruno (at) 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 /* 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 93 int 94 FUNC (DOUBLE x) 95 { 96 #if defined KNOWN_EXPBIT0_LOCATION && IEEE_FLOATING_POINT 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 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. */ 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 } 190
Indexes created Sat Feb 28 05:31:39 UTC 2026