X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;ds=inline;f=lib%2Fsignbitf.c;h=d03fcdd5c8ec683adfd3f7a43e61f41a39fc4bf2;hb=fa3486514bd8f15f8eb4c49821d0356b52e5a335;hp=c172b5fbefbc6f323fac60a0caa0066aee1242e4;hpb=f8cce822d6a82cadf0ea2907eb94a1017910322f;p=gnulib.git
diff --git a/lib/signbitf.c b/lib/signbitf.c
index c172b5fbe..d03fcdd5c 100644
--- a/lib/signbitf.c
+++ b/lib/signbitf.c
@@ -1,19 +1,18 @@
/* signbit() macro: Determine the sign bit of a floating-point number.
Copyright (C) 2007 Free Software Foundation, Inc.
- This program is free software; you can redistribute it and/or modify
+ 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 2, or (at your option)
- any later version.
+ 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, write to the Free Software Foundation,
- Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see . */
#include
@@ -21,7 +20,7 @@
#include
#include
-#include "isnanf.h"
+#include "isnanf-nolibm.h"
#include "float+.h"
#undef gl_signbitf
@@ -30,11 +29,19 @@ int
gl_signbitf (float arg)
{
#if defined FLT_SIGNBIT_WORD && defined FLT_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 (float) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
union { float value; unsigned int word[NWORDS]; } m;
m.value = arg;
return (m.word[FLT_SIGNBIT_WORD] >> FLT_SIGNBIT_BIT) & 1;
+#elif HAVE_COPYSIGNF_IN_LIBC
+ return copysignf (1.0f, arg) < 0;
#else
/* This does not do the right thing for NaN, but this is irrelevant for
most use cases. */