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/* Test for NaN that does not need libm.
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Copyright (C) 2007-2010 Free Software Foundation, Inc.
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program 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 General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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/* Written by Bruno Haible <bruno@clisp.org>, 2007. */
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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);
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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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#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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# 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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# 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 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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# define SIZE SIZEOF_FLT
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# define L_(literal) literal##f
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#define EXP_MASK ((MAX_EXP - MIN_EXP) | 7)
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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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#ifdef KNOWN_EXPBIT0_LOCATION
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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_))
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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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unsigned int exponent;
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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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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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return 1 & ~(m.word[0] >> 15);
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/* Little endian: EXPBIT0_WORD = 2, EXPBIT0_BIT = 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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return (m.word[1] >> 31) ^ 1;
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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 __DECC || (defined __sgi && !defined __GNUC__)
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/* The Sun C 5.0 compilers and the Compaq (ex-DEC) 6.4 compilers don't
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recognize the initializers as constant expressions. The latter compiler
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also fails when constant-folding 0.0 / 0.0 even when constant-folding is
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not required. The SGI MIPSpro C compiler complains about "floating-point
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operation result is out of range". */
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static DOUBLE zero = L_(0.0);
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DOUBLE plus_inf = L_(1.0) / L_(0.0);
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DOUBLE minus_inf = -L_(1.0) / L_(0.0);
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nan.value = zero / zero;
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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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/* 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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if (((m.word[EXPBIT0_WORD] ^ nan.word[EXPBIT0_WORD])
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& (EXP_MASK << EXPBIT0_BIT))
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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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/* The configuration did not find sufficient information. Give up about
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the signaling NaNs, handle only the quiet NaNs. */
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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_))
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/* Detect any special bit patterns that pass ==; see comment above. */
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memset (&m1.value, 0, SIZE);
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memset (&m2.value, 0, SIZE);
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m2.value = x + (x ? 0.0L : -0.0L);
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if (memcmp (&m1.value, &m2.value, SIZE) != 0)
added
removed
lib/isnan.c
