190 lines
6.9 KiB
C
190 lines
6.9 KiB
C
/* Test for NaN that does not need libm.
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Copyright (C) 2007-2023 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
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#include <config.h>
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/* Specification. */
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#ifdef USE_LONG_DOUBLE
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/* Specification found in math.h or isnanl-nolibm.h. */
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extern int rpl_isnanl (long double x) _GL_ATTRIBUTE_CONST;
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#elif ! defined USE_FLOAT
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/* Specification found in math.h or isnand-nolibm.h. */
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extern int rpl_isnand (double x);
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#else /* defined USE_FLOAT */
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/* Specification found in math.h or isnanf-nolibm.h. */
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extern int rpl_isnanf (float x);
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#endif
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#include <float.h>
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#include <string.h>
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#include "float+.h"
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#ifdef USE_LONG_DOUBLE
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# define FUNC rpl_isnanl
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# define DOUBLE long double
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# define MAX_EXP LDBL_MAX_EXP
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# define MIN_EXP LDBL_MIN_EXP
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# if defined LDBL_EXPBIT0_WORD && defined LDBL_EXPBIT0_BIT
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# define KNOWN_EXPBIT0_LOCATION
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# define EXPBIT0_WORD LDBL_EXPBIT0_WORD
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# define EXPBIT0_BIT LDBL_EXPBIT0_BIT
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# endif
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# define SIZE SIZEOF_LDBL
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# define L_(literal) literal##L
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#elif ! defined USE_FLOAT
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# define FUNC rpl_isnand
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# define DOUBLE double
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# define MAX_EXP DBL_MAX_EXP
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# define MIN_EXP DBL_MIN_EXP
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# if defined DBL_EXPBIT0_WORD && defined DBL_EXPBIT0_BIT
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# define KNOWN_EXPBIT0_LOCATION
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# define EXPBIT0_WORD DBL_EXPBIT0_WORD
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# define EXPBIT0_BIT DBL_EXPBIT0_BIT
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# endif
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# define SIZE SIZEOF_DBL
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# define L_(literal) literal
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#else /* defined USE_FLOAT */
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# define FUNC rpl_isnanf
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# define DOUBLE float
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# define MAX_EXP FLT_MAX_EXP
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# define MIN_EXP FLT_MIN_EXP
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# if defined FLT_EXPBIT0_WORD && defined FLT_EXPBIT0_BIT
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# define KNOWN_EXPBIT0_LOCATION
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# define EXPBIT0_WORD FLT_EXPBIT0_WORD
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# define EXPBIT0_BIT FLT_EXPBIT0_BIT
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# endif
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# define SIZE SIZEOF_FLT
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# define L_(literal) literal##f
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#endif
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#define EXP_MASK ((MAX_EXP - MIN_EXP) | 7)
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#define NWORDS \
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((sizeof (DOUBLE) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
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typedef union { DOUBLE value; unsigned int word[NWORDS]; } memory_double;
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/* Most hosts nowadays use IEEE floating point, so they use IEC 60559
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representations, have infinities and NaNs, and do not trap on
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exceptions. Define IEEE_FLOATING_POINT if this host is one of the
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typical ones. The C11 macro __STDC_IEC_559__ is close to what is
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wanted here, but is not quite right because this file does not require
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all the features of C11 Annex F (and does not require C11 at all,
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for that matter). */
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#define IEEE_FLOATING_POINT (FLT_RADIX == 2 && FLT_MANT_DIG == 24 \
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&& FLT_MIN_EXP == -125 && FLT_MAX_EXP == 128)
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int
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FUNC (DOUBLE x)
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{
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#if defined KNOWN_EXPBIT0_LOCATION && IEEE_FLOATING_POINT
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# 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
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/* Special CPU dependent code is needed to treat bit patterns outside the
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IEEE 754 specification (such as Pseudo-NaNs, Pseudo-Infinities,
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Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals) as NaNs.
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These bit patterns are:
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- exponent = 0x0001..0x7FFF, mantissa bit 63 = 0,
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- exponent = 0x0000, mantissa bit 63 = 1.
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The NaN bit pattern is:
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- exponent = 0x7FFF, mantissa >= 0x8000000000000001. */
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memory_double m;
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unsigned int exponent;
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m.value = x;
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exponent = (m.word[EXPBIT0_WORD] >> EXPBIT0_BIT) & EXP_MASK;
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# ifdef WORDS_BIGENDIAN
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/* Big endian: EXPBIT0_WORD = 0, EXPBIT0_BIT = 16. */
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if (exponent == 0)
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return 1 & (m.word[0] >> 15);
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else if (exponent == EXP_MASK)
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return (((m.word[0] ^ 0x8000U) << 16) | m.word[1] | (m.word[2] >> 16)) != 0;
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else
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return 1 & ~(m.word[0] >> 15);
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# else
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/* Little endian: EXPBIT0_WORD = 2, EXPBIT0_BIT = 0. */
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if (exponent == 0)
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return (m.word[1] >> 31);
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else if (exponent == EXP_MASK)
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return ((m.word[1] ^ 0x80000000U) | m.word[0]) != 0;
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else
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return (m.word[1] >> 31) ^ 1;
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# endif
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# else
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/* Be careful to not do any floating-point operation on x, such as x == x,
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because x may be a signaling NaN. */
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# if defined __SUNPRO_C || defined __ICC || defined _MSC_VER \
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|| defined __DECC || defined __TINYC__ \
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|| (defined __sgi && !defined __GNUC__)
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/* The Sun C 5.0, Intel ICC 10.0, Microsoft Visual C/C++ 9.0, Compaq (ex-DEC)
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6.4, and TinyCC compilers don't recognize the initializers as constant
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expressions. The Compaq compiler also fails when constant-folding
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0.0 / 0.0 even when constant-folding is not required. The Microsoft
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Visual C/C++ compiler also fails when constant-folding 1.0 / 0.0 even
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when constant-folding is not required. The SGI MIPSpro C compiler
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complains about "floating-point operation result is out of range". */
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static DOUBLE zero = L_(0.0);
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memory_double nan;
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DOUBLE plus_inf = L_(1.0) / zero;
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DOUBLE minus_inf = -L_(1.0) / zero;
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nan.value = zero / zero;
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# else
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static memory_double nan = { L_(0.0) / L_(0.0) };
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static DOUBLE plus_inf = L_(1.0) / L_(0.0);
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static DOUBLE minus_inf = -L_(1.0) / L_(0.0);
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# endif
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{
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memory_double m;
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/* A NaN can be recognized through its exponent. But exclude +Infinity and
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-Infinity, which have the same exponent. */
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m.value = x;
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if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD])
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& (EXP_MASK << EXPBIT0_BIT))
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== 0)
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return (memcmp (&m.value, &plus_inf, SIZE) != 0
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&& memcmp (&m.value, &minus_inf, SIZE) != 0);
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else
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return 0;
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}
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# endif
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#else
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/* The configuration did not find sufficient information, or does
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not use IEEE floating point. Give up about the signaling NaNs;
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handle only the quiet NaNs. */
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if (x == x)
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{
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# 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
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/* Detect any special bit patterns that pass ==; see comment above. */
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memory_double m1;
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memory_double m2;
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memset (&m1.value, 0, SIZE);
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memset (&m2.value, 0, SIZE);
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m1.value = x;
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m2.value = x + (x ? 0.0L : -0.0L);
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if (memcmp (&m1.value, &m2.value, SIZE) != 0)
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return 1;
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# endif
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return 0;
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}
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else
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return 1;
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#endif
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}
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