| 1 | /* Test for NaN that does not need libm. |
| 2 | Copyright (C) 2007-2016 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 | /* 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 | } |