From 8ffec2a3aba6f114784e11f89ef1d57a096ae540 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 27 Apr 2024 19:39:29 +0200 Subject: Adding upstream version 8.32. Signed-off-by: Daniel Baumann --- lib/signbitd.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 lib/signbitd.c (limited to 'lib/signbitd.c') diff --git a/lib/signbitd.c b/lib/signbitd.c new file mode 100644 index 0000000..ff8221f --- /dev/null +++ b/lib/signbitd.c @@ -0,0 +1,64 @@ +/* signbit() macro: Determine the sign bit of a floating-point number. + Copyright (C) 2007-2020 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include + +/* Specification. */ +#include + +#include +#include "isnand-nolibm.h" +#include "float+.h" + +#ifdef gl_signbitd_OPTIMIZED_MACRO +# undef gl_signbitd +#endif + +int +gl_signbitd (double arg) +{ +#if defined DBL_SIGNBIT_WORD && defined DBL_SIGNBIT_BIT + /* The use of a union to extract the bits of the representation of a + 'long double' is safe in practice, despite of the "aliasing rules" of + C99, because the GCC docs say + "Even with '-fstrict-aliasing', type-punning is allowed, provided the + memory is accessed through the union type." + and similarly for other compilers. */ +# define NWORDS \ + ((sizeof (double) + sizeof (unsigned int) - 1) / sizeof (unsigned int)) + union { double value; unsigned int word[NWORDS]; } m; + m.value = arg; + return (m.word[DBL_SIGNBIT_WORD] >> DBL_SIGNBIT_BIT) & 1; +#elif HAVE_COPYSIGN_IN_LIBC + return copysign (1.0, arg) < 0; +#else + /* This does not do the right thing for NaN, but this is irrelevant for + most use cases. */ + if (isnand (arg)) + return 0; + if (arg < 0.0) + return 1; + else if (arg == 0.0) + { + /* Distinguish 0.0 and -0.0. */ + static double plus_zero = 0.0; + double arg_mem = arg; + return (memcmp (&plus_zero, &arg_mem, SIZEOF_DBL) != 0); + } + else + return 0; +#endif +} -- cgit v1.2.3