Branch
Hash :
6ca831b0
Author :
Date :
2025-09-16T18:57:41
stringeq: prefer memeq to memcmp in other modules * lib/argmatch.c, lib/argmatch.h, lib/backupfile.c, lib/bcp47.c: * lib/boot-time.c, lib/csharpcomp.c, lib/csharpexec.c: * lib/file-has-acl.c, lib/gen-uni-tables.c, lib/get_ppid_of.c: * lib/get_progname_of.c, lib/getlogin_r.c, lib/getprogname.c: * lib/getumask.c, lib/isnan.c, lib/mbchar.h, lib/mem-hash-map.c: * lib/memcoll.c, lib/progname.c, lib/progreloc.c: * lib/pthread_sigmask.c, lib/quotearg.c, lib/readutmp.c: * lib/same.c, lib/signbitd.c, lib/signbitf.c, lib/signbitl.c: * lib/string-desc.c, lib/string.c, lib/string.in.h: * lib/unictype/3level.h, lib/unictype/3levelbit.h: * lib/uniname/uniname.c, lib/vc-mtime.c: Prefer memeq to memcmp when either will do. Do not make this change to files shared with glibc. Do not make the change to test files, at least not for now. * lib/gen-uni-tables.c (memeq): New static function, in same style. * modules/argmatch, modules/backupfile, modules/bcp47: * modules/boot-time, modules/csharpcomp, modules/csharpexec: * modules/file-has-acl: * modules/get_ppid_of, modules/get_progname_of: * modules/getlogin_r, modules/getprogname, modules/getumask: * modules/isnan, modules/mbchar, modules/mem-hash-map: * modules/memcoll, modules/progname, modules/pthread_sigmask: * modules/quotearg, modules/readutmp, modules/relocatable-prog: * modules/relocatable-prog-wrapper, modules/same, modules/signbit: * modules/string-desc, modules/stringeq, modules/uniname/uniname: * modules/vc-mtime: (Depends-on): Add stringeq.
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/* signbit() macro: Determine the sign bit of a floating-point number.
Copyright (C) 2007-2025 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file 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 Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include <math.h>
#include <string.h>
#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
'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 !memeq (&plus_zero, &arg_mem, SIZEOF_DBL);
}
else
return 0;
#endif
}