1/* Test for NaN that does not need libm. 2 Copyright (C) 2007-2010 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 Lesser 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 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 <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. */ 24extern int rpl_isnanl (long double x); 25#elif ! defined USE_FLOAT 26/* Specification found in math.h or isnand-nolibm.h. */ 27extern int rpl_isnand (double x); 28#else /* defined USE_FLOAT */ 29/* Specification found in math.h or isnanf-nolibm.h. */ 30extern 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)) 80typedef union { DOUBLE value; unsigned int word[NWORDS]; } memory_double; 81 82int 83FUNC (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_)) 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 __DECC || (defined __sgi && !defined __GNUC__) 121 /* The Sun C 5.0 compilers and the Compaq (ex-DEC) 6.4 compilers don't 122 recognize the initializers as constant expressions. The latter compiler 123 also fails when constant-folding 0.0 / 0.0 even when constant-folding is 124 not required. The SGI MIPSpro C compiler complains about "floating-point 125 operation result is out of range". */ 126 static DOUBLE zero = L_(0.0); 127 memory_double nan; 128 DOUBLE plus_inf = L_(1.0) / L_(0.0); 129 DOUBLE minus_inf = -L_(1.0) / L_(0.0); 130 nan.value = zero / zero; 131# else 132 static memory_double nan = { L_(0.0) / L_(0.0) }; 133 static DOUBLE plus_inf = L_(1.0) / L_(0.0); 134 static DOUBLE minus_inf = -L_(1.0) / L_(0.0); 135# endif 136 { 137 memory_double m; 138 139 /* A NaN can be recognized through its exponent. But exclude +Infinity and 140 -Infinity, which have the same exponent. */ 141 m.value = x; 142 if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD]) 143 & (EXP_MASK << EXPBIT0_BIT)) 144 == 0) 145 return (memcmp (&m.value, &plus_inf, SIZE) != 0 146 && memcmp (&m.value, &minus_inf, SIZE) != 0); 147 else 148 return 0; 149 } 150# endif 151#else 152 /* The configuration did not find sufficient information. Give up about 153 the signaling NaNs, handle only the quiet NaNs. */ 154 if (x == x) 155 { 156# 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_)) 157 /* Detect any special bit patterns that pass ==; see comment above. */ 158 memory_double m1; 159 memory_double m2; 160 161 memset (&m1.value, 0, SIZE); 162 memset (&m2.value, 0, SIZE); 163 m1.value = x; 164 m2.value = x + (x ? 0.0L : -0.0L); 165 if (memcmp (&m1.value, &m2.value, SIZE) != 0) 166 return 1; 167# endif 168 return 0; 169 } 170 else 171 return 1; 172#endif 173} 174